8/3/2019 01 Caves Karstic Phenomena 1
1/41
Caves and karstic phenomena
ITAL IAN HAB ITATS
1
8/3/2019 01 Caves Karstic Phenomena 1
2/41
ITAL IAN HAB ITATS
MINISTERO DELL AMBIENTE E DELLA TUTELA DEL TERRITORIO
M U S E O F R I U L A N O D I S T O R I A N A TU R A L E C O M U N E D I U D I N E
Caves and karstic phenomenaLife in the subterranean world
Italian habitats
Italian Ministry of the Environment and Territory Protection / Ministero dellAmbiente e della Tutela del Territorio
Friuli Museum of Natural History / Museo Friulano di Storia Naturale Comune di Udine
Scientific coordinatorsAlessandro Minelli Sandro Ruffo Fabio Stoch
Editorial commiteeAldo Cosentino Alessandro La Posta Carlo Morandini Giuseppe Muscio
Caves and karstic phenomena Life in the subterranean worldedited by Fabio Stoch
Text byMauro Chiesi Luca Lapini Leonardo Latella Giuseppe Muscio Margherita Solari Fabio Stoch
In collaboration with
Paolo Forti Maria Manuela Giovannelli
English translationby
Gabriel Walton
Illustrations by
Roberto Zanellaexcept for 89 (Enrico Zallot) and 90 (Marco Bodon)
Graphic design byFurio Colman
Photographs by
Archivio Circolo Speleologico e Idrologico Friulano 14/2, 40, 41, 49, 50, 56, 60/1, 78Archivio Museo Friulano di Storia Naturale 21, 22, 23Archivio Unione Speleologica Bolognese 11, 12, 17, 27, 28, 29, 30, 43, 45, 47, 54/2, 125/1, 132
Adalberto DAndrea 8, 14/3, 19, 35, 39, 44, 62, 74, 133, 134, 140, 148Sergio Dolce 90Fulvio Gasparo 52, 94, 99, 103/3, 107, 109/2, 116/1
Salvatore Inguscio, 103/1, 103/2Enrico Lana 95, 100, 104, 106, 109/1, 109/3, 118Luca Lapini 54/1, 60/3, 60/4, 122, 123
Leonardo Latella 63, 64, 69, 112/1, 112/3, 113/2, 126Giuseppe Muscio 60/2, 85, 127Tiziano Pascutto 88, 113,/1, 117, 121/2, 125/2
Giuseppe Lucio Pesce 87/1Mauro Rampini 54/3, 112/2Federico Savoia 14/4, 156Pino Sfregola 152
Margherita Solari 14/1Fabio Stoch 54/5, 92, 93, 96, 101, 124, 143Franco Tiralongo 130
Elido Turco 129Stefano Zoia 54/4, 87/2, 105, 108, 111, 114, 116/2, 116/3, 119, 121/1
2002 Museo Friulano di Storia Naturale, Udine, Italy
Even partial reproduction of texts and photographs is forbidden. All rights reserved.ISBN 88 88192 03 4
Cover photo:Cave of Santa Barbara, Sardinia (photo: Unione Speleologico Bolognese)
8/3/2019 01 Caves Karstic Phenomena 1
3/41
Directive 92/43 of the European Community, issued on May 21
1992, and commonly known as the Habitat Directive,
represents a considerable improvement in overall environmental
policy. The innovative approach of the Directive lies in its
recognition of the complex and crucial role played by interactions
between animal species, living plants, and the ecosystem
surrounding them.
It was within the perspective of the Habitat Directive that long-term
activities could be planned and carried out.
In order to inform the general public about the natural history of
Italy and to publicize the results of scientific research, the Italian
Ministry of the Environment and Territory Protection has planned
publications focusing particularly on the environment.
Italian habitats is a series aimed at improving present knowledge
of environments at risk of degradation or even of disappearance -
habitats in which special and noteworthy fauna and floracan be found.
The Ministry appointed the Friuli Museum of Natural History to
prepare this series of monographs, starting with the present volume
on karst phenomena.
The flexible but scientifically correct structure of these volumes
describes Italian habitats of international interest. This important
series, while enhancing common knowledge about the
environment, will contribute towards laying the foundations for
proper management of natural resources - that great heritage
belonging to us all.
Altero MatteoliItalian Minister of the Environment and Territory Protection
8/3/2019 01 Caves Karstic Phenomena 1
4/41
Intoduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Giuseppe Muscio
Karstic phenomena and speleology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Giuseppe Muscio
Biospeleology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Leonardo Latella Fabio Stoch
Taxonomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Fabio Stoch Leonardo Latella Luca Lapini
Protection and conservation of the subterranean environment . . . . . . 131
Mauro Chiesi Luca Lapini Fabio Stoch
Suggestions for teaching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149Margherita Solari
Select bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
ContentsItalian habitats
1
Caves and
karsticphenomena
2
Springs and
springwatercourses
3
Woodlands
of the PoPlain
4
Sand dunes
and beaches
5
Mountain
streams
6
TheMediterranean
maquis
7
Sea cliffs androcky
coastlines
8
Brackishcoastal lakes
9
Mountainpeat-bogs
10
Realms ofsnow and ice
11
Pools,ponds and
marshland
12
Aridmeadows
13
Rocky slopesand screes
14
High-altitudelakes
15
Beechforests of the
Appennines
8/3/2019 01 Caves Karstic Phenomena 1
5/41
IntroductionGIUSEPPE MUSCIO
9
Talking about caves to people who have never visited one is difficult. Once,
during a meeting on cave photography, a discussion arose regarding the best
techniques for the best results, and one well-known cave photographer
reminded those present that a true photograph of a cave is ... completely
black! And it is true: in caves, light is an extraneous element, a real form of
pollution which man brings into the darkest environment imaginable, into a
silence broken only by the dripping of water or the sound of sometimes rapidly
moving waters.
Few places other than caves have inspired mans imagination: in the past, he
used them as dwellings and for protection, but he rarely penetrated further
than light was able to reach - that limit beyond which mystery hovered,
accompanied by fear and superstition.
Caves have also been places of worship or of fortification, but only from the
19th century onwards have they been systematically explored and sc ientifically
studied. Since then, man has understood how very singular the cave
environment is: limited in extent, protected by rock, and with a particularly
stable climate. But for this very reason, he also understood how delicate the
equilibrium of the underground world is, and how easily it can be upset.
Thus, in recent decades, we have realized the importance of respect for and
protection of karstic phenomena. Although it covers the subterranean world,
this type of protection must necessarily start from the surface of the earth,
where karstism is widespread.
The term karstism derives from Carso (Karst), the name of the geographic
area between Italy and Slovenia, which has become synonymous with a
certain type of landscape or, more simply, of everything morphologically linked
with caves. Carso in fact derives from karren, a proto-European term
which simply means rock - grastin Slovene, in use since 1177; krasin Croat,
used since 1230; carsoin Italian, and Karst in German, in which the original
root is clearly preserved. It is not surprising that the root means rock,
because in karstic areas rocks outcrop frequently and are wonderfully
modelled. The landscape is thus characteristic, partly because it is not only
superficial but also, indeed mainly, underground.
The opportunity to increase our knowledge of karstism in Italy in order to
Subterranean lake in Grotta d i Punta Galera (Palinuro, Campania)
8/3/2019 01 Caves Karstic Phenomena 1
6/41
1110 protect it better is fully justified: there are many endemic forms in the
subterranean fauna and interesting minerals which are typical of the
subterranean environment. However, there is also a very simple reason for
protecting it which, alone, is abundantly clear to all: at least 50% of Italian
drinking water is of karstic origin (the percentage is even higher in some
southern areas of the country) and this figure is certainly destined to
increase in the future, due to the various forms of pollution involving the
steadily deeper and deeper watertables of the plains. Equally clear is the
fact that few environments are so vulnerable and so slow to change as the
subterranean one.
Today, the karstic environment is not only intensively explored but is also a
source of scientific information, a reservoir of p rime importance. In the past,
caves were the places of the imagination, the dwellings not only of
prehistoric man but also of mythical beings which populated - and still
populate - folklore.
Thus, we have learned to observe natural cavities in the earth as a highly
variegated source of information. Speleology - the science which studies them -
comes from the Greek spelaion(cave) and logos(study), and now attracts
research-workers from a whole range of fields: geology, mineralogy, biology,
ethnography, archeology, etc., and the speleologist is, basically, a naturalist
in the widest sense of the word. There are many only slightly known, or
completely unknown, aspects of caves, like that of mineralogy: for example,
already in prehistoric times, men used the gypsum from caves in the Tuscan-
Emilian Appennines (e.g., Calindri), and nitrates were exploited even earlier.
More recently, many caves have been completely emptied of t heir contents of
bat d roppings, since the guano, as it is called, is an excellent natural fertilizer.
Speleology came into being as a science in its own right at Trieste in the 19th
century. It was the natural response of a large city which, then in full
expansion, was searching for new water supplies in its hinterland. And its
hinterland was the classic Karst, in which the only river of a certain size, the
Timavo, mainly flows underground. One indication of the amplitude of
speleology in Italy is that there are at least 10,000 speleologists, and more
than 33,000 caves have been explored and surveyed. Although some are
several dozen kilometres long or hundreds of metres deep, very many are
small. But this does not mean that they do not contain very fine natural
beauties.
Natural cavities in the earth are often exploited from the economic viewpoint.
Among the various Italian caves open to the public, four are well-known:
Grotta di Castellana in Puglia (Apulia), Grotta di Frasassi in the Marches,
Grotta Azzurra in Campania, and Grotta Gigante in Friuli-Venezia Giulia, with
hundreds of thousands of visitors every year. On one hand, the caves bring in
local tourist revenue; on the other, the tourists themselves cause many
environmental problems regarding the proper conservation of underground
environments: not just pollution due to the waste they leave or the damage
they do - more simply the disturbance created by the sole presence of man
influences the delicate equilibrium of the subterranean climate (temperature
and humidity).
Writing about karstism is therefore not a simple matter: it is almost impossible
to put down on paper the feelings we experience when we enter a cave and
penetrate its absolute darkness. For a speleologist, whether the cave is long or
short is not important: what counts is the fascination of exploration. There are
only a few very large caves, richly decorated with concretions or concealing
important findings, but no cave lacks its own hidden mystery. The true
passion which urges the speleologist to adventure beneath the earth is
knowledge, the exploration of an underground world which no- one or very few
have ever violated, the desire to study a phenomenon which, perhaps only on
a small scale, is always unique, completely different f rom its surroundings.
Concretions in Grotta di Valdemino (Liguria)
8/3/2019 01 Caves Karstic Phenomena 1
7/41
13
The natural environment which surrounds us, which we observe without
thinking about it, is generally called panorama. When our gaze embraces a
set of characteristics which are all somehow linked, we call it landscape.
Thus, the dry karstic landscape is often compared with one containing
superficial bodies of water of various kinds, because one of the peculiarities of
a karstic area is precisely the absence of any clearly observable surface
water network.
The karstic process is that set of mainly chemical factors which lead to the
dissolution of carbonatic rocks (limestone, dolomia), forming surface cavities
(dolinas) or underground ones (caves), creating a subterranean water network,
and modelling outcropping rocks in a very typical way. However, not all natural
cavities owe their origin to karstism: some, for example, may form in or under
glaciers, or in lava, or be of mixed origin.
There have also been lengthy debates on what effectively constitutes a cave
and what kind of empty space in rock, carbonatic or not, enters this category.
For the Italian Cave Registry, listing natural cavities which have been offic ially
surveyed and described, a cave is a cavity sufficiently large to allow access to
humans and more than five metres long. This restriction is not applicable if we
consider caves as developing morphological elements within which the
widening of a small crack in the rock may lead to a vast subterranean system
which is later perhaps destroyed by collapse or occlusion or, in the long
term, involved in the various processes of erosion to which emerged land is
subject.
The karstic process
Limestone is a rock composed almost entirely of calcium carbonate (CaCO3),
a compound with very low solubility in water. However, in the presence of
carbon dioxide (CO2), the water becomes more aggressive and acid, and
dissolves the calcium carbonate, forming calcium bicarbonate, according to
the following reaction: CaCO3 + H2O + CO2 Ca++ + 2HCO3-. The
equilibrium shifts right or left according to pressure and temperature.
Karstic phenomena and speleologyGIUSEPPE MUSCIO
Extensive karstifiable rocks in Sardinia
8/3/2019 01 Caves Karstic Phenomena 1
8/41
Superficial karst formsExtremely variable in size; the best known arelimestone pavements (also called karren orkarrenfeld), dolinas and solution pans (or kamenitza)
Swallow holesWater reaches the subsoil not only through minutecracks in rock, but also through true natural shafts.These are considerably modelled by the waterwhich passes through them, first creating a circular
cross-section, when water flows under pressureand occupies the entire shaft, and later scouringout part when flow diminishes and water acts onlyon one wall
Collapse depositsAt the bottom of large shafts and in areas ofextreme fracturing, large quantities of collapsedmaterials may accumulate. This phenomenonsometimes leads to the creation of large halls insubterranean karstic systems
Subterranean riversEntire stretches of caves may be occupied bysometimes large watercourses. The walls often
show traces of how the water regime developed,both in the shape of the cross-section and in thepresence of special forms of excavation on thewalls (scallops)
Conduits and siphonsThe lowest parts of karstic systems are typicallyfilled with completely flooded tunnels, calledsiphons. According to the morphology of the area,these siphons may meet in areas in which watergenerally flows freely.
1514 The strict meaning of the term karstic process refers only to the chemical
reaction which affects calcium carbonate and, consequently, only to pure
limestone.
Today, the term has been expanded and karstic phenomena is accepted to
refer to everything regarding the corrosive activity to which carbonates are
subjected (thus, limestone and dolomia) and also to gypsum (calcium
sulphate) and any other solubilizable rock (rock-salt, quartzite).
Although the above reactions are the main causes of the development of
karstism, they are certainly not the only ones and there are many variables
The superficial part of a karstic area is
intensely modelled and shows only a
few traces of watercourses.
The action of water creates structures
like karrenand dolinas.
It then flows into the subsoil through
the network of cracks, some of which
widen to form true shafts,large enough to allow people to
descend them. Through this dense
network, water reaches first the
percolation or vadose zone where, for
example, it drips slowly, or flows as a
thin sheet down whole walls of rock.
Deeper down are those stretches of
the karstic system where water flows
more regularly (galleries with
subterranean streams, waterfalls,
small lakes, etc.) until the so-called
phreatic zone is reached. Still deeper
inside the rock is the water-saturated
area with completely flooded galleries,called conduits under pressure.
A succession of this type is the result
of long, complex evolution of the
territory, in which external factors
intervene, e.g., tectonics, or variations
in water-table levels.
A model cross-section of a karstic area Giuseppe Muscio
8/3/2019 01 Caves Karstic Phenomena 1
9/41
1716 which come into play: from the characteristics of the rocks to the condition of
the vegetal cover, from the local climate to a series of mechanisms
accompanying the main chemical reactions.
Starting from lithotypes, not all limestones, as already mentioned, are pure: as
well as calcite (calcium carbonate), small quantities of various minerals are
always found, in particular dolomite (carbonate of calcium and magnesium),
forming passages between limestone and dolomia. Karstic phenomena may also
develop in these rocks; indeed, a small percentage of magnesium favours them.
Therefore, although waters rich in CO2 can dissolve carbonatic rocks, to
what extent they may do so is difficult to establish. First of all, we must bear in
mind the climatic conditions and in particular the local level of rainfall, since
water is an essential component of the reaction. The quantity of mass which is
removed (rate of ablation) over a certain period of time has been calculated
experimentally, taking into account the fact that karstic corrosion occurs not
only on the surface but above all in the subsoil. Therefore, reported values do
not refer to the removal of superficial carbonate and do not correspond to a
simple lowering of the topographic surface, but to the entire rock mass
which is dissolved, including that below ground. For a mean precipitation
level of 1000-1500 mm/year, mean ablation rates of 50-100 mm/1000 years
may be hypothesized for the Mediterranean area; values for Alpine areas are
slightly higher.
Recent measurements made in Friuli-Venezia Giulia have defined carbonate
erosion rates of 20-40 mm/1000 years. i.e., slightly lower, but they refer only to
outcropping rocks and may thus be compared with those quoted above. This
means that karstism alone, in 10,000 years, can remove the equivalent of one
metre of thickness from an Alpine carbonatic massif. This is a very significant
value; in gypsum, the figure is t en times greater.
If we examine the classic reaction, the presence of CO2 clearly plays an
essential role, since it makes water aggressive towards carbonates. CO2 is
present in the atmosphere, but its quantities may increase considerably in the
soil, according to the vegetal cover, and its solubility is greater in cold ratherthan in warm waters. This means that, other conditions being equal, cold
waters are more aggressive than warm ones; but in hot, humid climates the
production of CO2 due to decomposition of vegetal residues is very high and it
is for this reason that, although the waters are warmer, local condit ions favour
more marked karstic phenomena.
The question of water temperature is important if, for example, we think of
high-altitude karsts, where snow meltwater easily generates superficial
karstic forms - always, of course, if they flow on carbonatic rocks. Grotta Paradiso at Fluminimaggiore (Sardinia)
8/3/2019 01 Caves Karstic Phenomena 1
10/41
1918 It is also clear that, although the role of CO2 is essential to make waters
aggressive, the possible presence of strong acids enhances their corrosive
action, giving rise to what are called hyper-karstic phenomena. Strong acids
may be present in the external environment, but they are more commonly
found in the rocks themselves: for example, H2SO4 is linked to the reaction of
oxidation of pyrite or H2S of deep origin.
But how do meteoric waters enter carbonatic rocks? Rainwater, which is
enriched in carbon dioxide in the atmosphere and soil, reaches the rocky
surface and is already aggressive.
It may corrode the surrounding rocks when long lines of discontinuity meet,
since they are the preferential directions of flow of superficial waters, and it
begins to excavate the rock, f iltering inside it. At the same time, however, the
water becomes saturated in calcium carbonate and cannot continue its
corrosive activity beyond a certain point: other waters then widen cracks
further. We know that theoretical saturation levels may be exceeded by karstic
waters according to conditions of pressure and temperature, and also that
mixing of waters with different chemical characteristics favours the
development of karstic phenomena. With this knowledge, we can reconstruct
the physical elements which are required for the karstic process to begin.
These are:
1. carbonatic rock containing discontinuities (fractures, faults, etc.);
2. water containing dissolved carbon dioxide;
3. differences in altitude, permitting water movement.
The second point has already been analysed. It is clear that water movement
is essential for the development of karstic phenomena and to remove those
fragments which, not soluble by CO2-enriched waters, could fill the cracks
and prevent further speleogenesis (i.e., the formation of natural cavities).
So let us examine further the first point: discontinuities are the natural
consequences of deformational events undergone by the rocks during their
geological history.
The surroundings are thus full of cracks, mainly only a few microns thick andoften not distinguishable on the surface because they have been altered by
modelling, but they are sufficient to allow water to percolate down. In the past,
a theoretical limit to the downflow of waters was believed to exist, due to the
idea that, at a certain depth (500 or 1000 metres), cracks tended to close as a
result of the enormous mass of overlying rock, thus preventing the passage of
water. We now know that enormous quantities of water are found during the
excavation of tunnels, even if they are overlain by thousands of metres of rock
- an example is the Mont Blanc tunnel.
Until now, in examining speleogenesis - that set of processes which create
karstic cavities - we have referred to the fundamental role played by chemical
corrosion. Although this is essential during the first speleogenetic phase - that
is, when the first subterranean conduits form - as they gradually become
larger, erosion also comes into play. This is a purely mechanical action on thepart of the more resistant granules which chemical reactions free from the
carbonatic matrix (commonly fragments of flint, quartz or ferrous minerals) and
which swirling waters scour against the rock, abrading it.
As karstic conduits progressively widen, collapses favour the formation of
large halls at points in which rock fracturing is especially intense, often at the
point where lines of tectonic origin meet. Research undertaken during recent
decades has definitely changed the original view of the fathers of karstism,
who were, in a certain sense, purists. We now know that there are so many
Grotta Nuova at Villanova (Friuli)
8/3/2019 01 Caves Karstic Phenomena 1
11/41
polje, and are often used for agriculture because of their very fertile soil, with a
superficial, seasonal, water network. In Puglia (Apulia), the word Pulo is used
for similar shapes: e.g., the Pulo of Altamura and that of Molfetta.
Special shapes are due to considerable superficial dissolution which, freeing
blocks of limestone which may become isolated from each other, are often
modelled into strange shapes and aspects, the so-called cities of stone.
Among the superficial forms are springs, either free-flowing (in which water
CATEGORIA FORME PICCOLE FORME MEDIE FORME GRANDI
ACCUMULATION SOLUTION PANS
OVERLAND FLOW KARREN SUBSIDENCE DOLINAS CLOSED VALLEYS
IN FILTRATION C AVERNOU S K ARREN DOL IN AS, SN OW SHAFTSPERCOLATION SHAFTS
CREVASSES CORRIDORS KARSTIC VALLEYS, UVALA
OUTFLOW KARST SPRINGS POLJE BLIND VALLEYS, POLJE
KARSTIC LAKES
CATEGORY SMALL FORMS MEDIUM-SIZED FORMS LARGE FORMS
2120 variables which enter into play in the origin and development of a karstic
cavity, that they certainly cannot be reduced to the simple formula: water +
carbon dioxide + calcium carbonate: although everything starts from a simple
corrosive reaction, all kinds of morphogenetic agents are at work.
Superficial karstic forms
Karstism almost always begins on the surface, i.e., in outcropping rocks,
leading to what is defined as a karstic landscape, composed of highly
differentiated forms according to the various features of the outcropping
lithotype, and the local climate, with particular reference to rainfall: we thus
speak of tropical karst, temperate karst, and so on. Forms are also
generally grouped according to size.
In Italy, karstic zones occupy more than 27% of the entire territory and there
are widespread high-altitude and temperate karst areas, including, for
example, the area between Venezia Giulia and Slovenia, which is part of the
so-called classic karst.
The superficial forms are grouped into categories partly according to size (the
original term is often based on German or Slovenian words; see table, page 21).
Ponds form where rainwater collects in small depressions; overland flow may
give rise to karren, solution flutes or rills, and solution runnels, distributed
according to the gradient of the outcrop.
Dolinas may have various origins and shapes: they are large areas where the
original terrain sank, due to dissolution or collapse. They are circular or
elliptical in shape, and range from a few metres to several dozen metres
across. Larger forms, sometimes several kilometres in diameter, are called
Two types of dolina evolution Surface karst landforms due to impact and streaming of raindrops
8/3/2019 01 Caves Karstic Phenomena 1
12/41
2322 comes from a partially well aerated natural cavity) and those of Vaucluse
type (in which the whole cross-section of the natural cavity is occupied by
water). Then there are karstic lakes , similar in shape to classic lakes but lying
on karstifiable rocks, with mainly subterranean supply. One of the best-known
example is the lake of Doberd in the Karst near the river Isonzo.
Subterranean karstic forms
The ideal cross-section of an already evolved karstic territory may be
subdivided into: an outcropping belt, containing all superficial morphologies
and lacking permanent bodies of water; and the immediately underlying
section, which has a series of shafts and galleries of karstic origin, where
water is present only sporadically after rain.
Further down (vadose zone) are karstic systems with water and, lower still,
near what is called the p iezometric surface, all the cavities in the rock are filled
with water (saturated or phreatic zone).
The modelling action of water in a karstic subsoil creates forms which are
commonly subdivided into karstic conduits and wall forms.
interlayer cavity
runnels
pool
pool
grooves
karstic hole
large runnels
Karst springs: free-flow ing water (left) and Vaucluse type (right) Lake of Doberd (Isonzo Karst): one of the best classic examples of a karstic lake
Names of some common karst forms on rock
Superficial karst forms: small meander, solution pans, grooving
8/3/2019 01 Caves Karstic Phenomena 1
13/41
2524
Dolinas are typical superficial karst
forms found in temperate climates. A
dolina is defined as a closed hollow,
between a few metres and 1 km in
diameter, and composing a simple
hydrographic unit.
The perimeter is generally circular or
subelliptical, although there are alsoirregular or complex forms resulting from
the fusion of a variable number of
dolinas (uvala).
According to the ratio between mean
diameter and depth, dolinas are
classified into three categories: flat,
when the ratio exceeds 2; funnel-
shaped, when it is less than 2; and deep,
when the depth is greater than the
diameter and the slopes are subvertical.
Dolinas are generated by normal
dissolution phenomena by fast-flowing
water moving towards a topographically
depressed point, leaching and corrodingthe rocky slopes. The central point is
often absorbent, due to microcracks in
the rock or swallow holes, not always
visible because they are covered by
debris or soil which, steadily deepening,
makes up the bottom of the dolina.
Superficial dissolution also occurs under
the soil cover and is due to normal
solution, but it may also be related to
periodic variations in the concentration
of carbon dioxide produced by the
biological activity of micro-organisms or
vegetation. At depth, the effects of
corrosion due to mixing of waters,
cooling, or enrichment in magnesium
prevail.
The soil on the bottom of a dolina is
often residual, the result of accumulated
insoluble minerals which compensate
the basic pH in soils deriving from
carbonatic rocks.
Dolinas which developed according to
this model (normal solution) are often
hemispheric or funnel-shaped, and may
occur both in limestone and in rocks
with various degrees of solubility
(dolomitic limestone, etc .). They may
also form in coherent non-soluble rocks
like sandstone and, if they rest on
soluble materials subject to karstism,may cause the collapse or subsidence of
underlying formations.
Very different is the evolution of collapse
dolinas, which have subvertical slopes
and originate from the fallen ceilings of
caves: in this case, dissolution is a factor
of secondary importance.
Although the topographic position of a
dolina may be random, it often reflects
the presence of lithological or tectonic
structures, such as the dip of rock layers
or the directions of faults. Morphology
too (e.g., perimeter lengthening) may be
correlated with these factors.Large dolinas, with diameters exceeding
100 metres, may have their own micro-
climates, with thermal inversions
accompanying inverse stratification of
vegetation and the presence of more
markedly cold-loving plant species.
The micro-climate of a dolina is due to
several factors. In the first place, cooling
by radiation on a concave surface is
greater than on a corresponding flat
area, being directly proportional to the
surface exposed. On the bottom, the soil
is usually saturated in water and
evaporation causes further cooling. In
addition, in autumn and winter, from the
first slope to enter shadow (the western
one) cold air descends towards the
bottom and lowers the temperature in
the hollow even before sunset;
conversely, in the morning, it is reached
by the sun much later than the south-
facing slope. The consequence of these
factors, partially attenuated during
summer, is a strong average thermal
gradient - about 7per 100 metres of
depth, i.e., about 12 times greater than
the external gradient in temperate
climates. This means that, temperature-
wise, descending 50 metres into a dolina
is equivalent to climbing a hill 600
metres high. In these conditions of
microthermy on the cooler southern
slope (exposed to the north), the
resulting vegetation may be a mixture of
local species which prefer cool
environments, or ones generally typical
of higher altitudes.
In this case, the four slopes of the dolina
are covered with different plant
associations, having intermediate
conditions on the western and eastern
slopes and extreme ones on the
northern and southern ones. These
differences are also evident when the
gradient of the slopes are symmetrical,
and depend only on topography: this is
called climatic continentalization.
In very large dolinas, the inversely
stratified vegetation is very c lear and
particularly interesting: in some cases, a
complete series of plant associations
may be found, typical of gradually higher
altitude belts until we come to cenoses
with dwarf pine typical of high-mountain
and sub-Alpine belts.
The peculiarities of dolinas thus
represent an element of discontinuity
which is not only morphological: they
introduce diversity and enrichment into
the environment by means of the
selective organization of flora into
different types of vegetation.
Dolinas
beech
ice
Oriental spruce
dwarf pine willow rhododendron Alpine f lora
silver fir
1100
1050
1000
1150
Seriation of vegetation in a steep dolina in the Italian Karst. Section illustrates phenomenon ofinverse vegetation in relation to microclimates occurring inside cavity
Margherita Solari
8/3/2019 01 Caves Karstic Phenomena 1
14/41
2726 Karstic conduits are created by the chemical action of water along
discontinuities: at the beginning of speleogenesis, the conduits are completely
filled with water under pressure and may later develop into vadose conduits in
which water f lows freely, with a consequent increase in its mechanical action.
Vertical shafts are forms created by percolation. Water also models the walls
of karstic conduits, e.g., in scalloped forms.
Subterranean karstic systems are thus composed of galleries and shafts,
sometimes filled with water (act ive) or abandoned (fossils). However, these
two terms seem to be inappropriate, because the same system often has both
active and inactive parts, or parts which are active during periods of intense
rainfall and not active during the normal water regime.
One particular aspect of speleogenesis in karstic areas is due to hydrothermal
fluids, which are highly corrosive, favouring the formation of large halls, the
development of which is often not influenced by cracks.
In any case, speleogenesis requires lengthy periods of time - in the karstic
environment, from hundreds of thousands to millions of years. Evolution is
more rapid if hyper-karstic or thermal factors intervene; even more rapid is
erosion of gypsum deposits; the filling-in of some caves in the Emilia-
Romagna Appennines has been dated, and only lasted about 5,000 years.
The whole karstic phenomenon of the Gessi del Bolognese is believed to havedeveloped over the last 100,000 years, and most of the caves are less than
18,000 years old.
Non-karstic cavities
Not all natural cavities are due to true karstism: there are some caves of a
certain importance which open inside conglomerates and which may be very
large indeed. This happens because waters act by dissolving the carbonate
which cements conglomerates, thus freeing pebbles and matrix, which are
then removed by mechanical action. These caves often contain thick deposits
of clay and, being subjected to frequent collapses, change their shaperelatively rapidly. Among the most interesting are the caves in the Miocene
conglomerates of Montello (Veneto), some of which are more than 1 km long
(the Busa di Castel Sotterra extends fo r nearly 7 km).
Some caves which develop at the contact between different lithotypes are
considered of mixed origin: there are many which originate at the interface
between carbonate and flysch. The first speleogenetic phase is due to
corrosion of carbonatic rocks, but then the cave expands due to strong
erosion of the flyschoid complex (composed of alternating marl, sandstone
Lava conduit on flanks of Mount Etna (Sicily)
and clay). Caves of this type have been studied in detail in Friuli: the complex
of the Grotta Nuova di Villanova, more than 7 km long, develops precisely at
the contact between a conglomeratic bank (in which both clasts and matrix
and cement are all composed of calcium carbonate and thus the lithotype
behaves, from a chemical viewpoint, like limestone) and Eocene flysch.
Other types of mixed cave are sea grottoes. Their terminal portions, having
originated from mixtures of salt and karstic waters, have often been widened
by the destructive force of the sea.Instead, very far from any kind of karstic origin are caves resulting from lava
flows: widespread mainly around Mount Etna in Sicily, they also occur in other
Italian regions. These caves are called syngenetic, since they usually form over
very short periods of time (from a few days to a few weeks), together with the
rocks which contain them. They are also highly unstable and often do not last
long, being rapidly destroyed if their ceilings collapse. However, it is relatively
easy to date them, when the age of the various lava flows is precisely known.
There are several morphologies, due to both type of lava and mode of
8/3/2019 01 Caves Karstic Phenomena 1
15/41
2928
formation, but the Etna lava caves are grouped into two large categories:
rheogenetic (superficial), and of f racture type. Rheogenetic caves are simply
the empty spaces left by the flow of magma in lava tunnels. They are generated
by liquid lava flowing on a solid surface: the upper part, in contact with the air,
cools and solidifies quite rapidly, while the part underneath continues to flow,
and then leaves an empty space once the supply of lava ceases.
Fracture caves extend in depth along discontinuities sometimes created by
seismic events. Intermediate or mixed forms may also exist, created by a
combination of the two types.
Although it may appear strange, as regards their genesis, lava caves are similarto glacier caves, which also form as a result of flow. In glacier caves, water from
melted ice excavates galleries and shafts, often extremely short- lived.
Climate in subterranean environments
The problem of subterranean climates is of ten underestimated. However, if we
consider to what extent it influences, for example, the fauna living in this
particular environment or, from another viewpoint, the fact that caves were
once extensively used as places in which to preserve food, we realize that this
is not simply a secondary aspect of speleology.
The first point to examine is temperature: in general, apart from the first few
yards of a cave from its entrance inwards, which is influenced by the external
climate, the temperature deep inside is the same throughout the year and is
very close to the mean value of the temperature in the area where the cave
itself is located. This is because fluids (water and air) circulate in caves, and
they determine the temperature. If we base our calculations on the thermal
gradient of the earth, we should have an increase of about 3C for every 100
metres of depth (values measured during the excavation of mine shafts, for
example) but, apart from very small variations, vertical caves such as shafts
maintain their temperature even at depth. For example, in the depths of the
high-altitude carsi (i.e., in carbonatic massifs at altitudes exceeding 1500-
2000 metres), the temperature is generally close to zero, since the caves were
created mainly by the snow meltwater which flows through them.
Due to their isothermy, caves are thus relatively warm in winter and cool in
summer. In low- altitude areas, temperatures range from about 10C in the pre-
Alpine belt to 16-18C in caves in Sardinia or Puglia (Apulia).
There are, of course, special cases like those of lava caves, which have their
own special climatic conditions, with very high temperatures if they have beenrecently formed. But temperature differences do exist in karstic caves, due to
the temperature of their subterranean rivers, the waters of which may come
from several places.
More constant than the temperature
inside natural caves is relative
humidity, ranging from 95 to 100%.
Lower values are only found near the
entrances and in particularly dry
climates.
Air currents inside karstic systems are
of considerable interest. They areusually quite slow, but may be
significant if the cave has several
entrances or ot her kinds of links with
the external world. Currents depend
on season since, as mentioned
above, the temperature of the air in
caves is lower than the outside
temperature in summer and higher in
Ice concretions. Grotta della Spipola(Emilia-Romagna). Swellings indicate mom entsof relatively higher temperature (shortly aftermidday) when ice starts to melt and thenfreezes again
Grotta della Spipola, in gypsum near Bologna (Emilia-Romagna)
8/3/2019 01 Caves Karstic Phenomena 1
16/41
Waters in caves always contain mineral
salts. When they flow inside a cave,
they may become oversaturated and
give rise to chemical deposits.
These deposits have always been
divided into two subgroups:
concretions and mineralizations, the
difference essentially being based onthe d egree of crystallinity: high in
mineralizations and low in concretions.
In fact, in nature there are many
macrocrystalline or even
monocrystalline concretions, just as
there are cryptocrystalline or definitely
amorphous mineralizations: in practice,
the possibilities are infinite. Thus,
although subdivision based on the
degree of crystallinity is not
scientifically valid, it is useful for better
understanding of the various aspects of
the phenomenon.
One particular type of cave deposit isthe result of accumulations of bat
droppings, called guano, used in the
past thanks to its excellent properties
as a fertilizer. It plays a significant role
in the subterranean ecosystem and
may sometimes even influence the
genesis of certain minerals (e.g.,
brushite).
Concretions
This term was once given to deposits of
calcium carbonate, but was then
extended to gypsum.
Then, as mineralogical knowledge o f
the subterranean world expanded, it
was discovered that many other
minerals could give rise to concretions
which were absolutely identical in form
and evolutionary mechanism to those
of calcium carbonate: in Italy, for
example, there are many well-known
concretions of sulphur.
Although several factors may concur to
modify the form and external aspect of
cave deposits, water movement
undoubtedly most greatly influences
their external aspect, so that the most
logical classification of concretions is
based on this parameter.
Concretions resulting
from water movement:
slow dripping:
stalactites, tubular forms,
draperies and curtains
dripping by impact:
stalagmites, conulites,
splash concretions, circles
water flow:
encrustations, columns, b arriers,
moonmilk
submersion:pisolites, cave clouds, coralloids,
moonmilk
capillarity:
eccentric and disc-shaped forms
evaporation:
floating crystals, coralloids, trays
condensation:
rims, boxwork, oriented coralloids,
moonmilk
salient:
geysermites
The first group contains the most
common and numerous concretions,
which is why they are further divided
into two subgroups: the effect of the
gentle detachment of a drop of water is
very different from that of its imp act on
a surface below, and gives rise to very
different forms.
3130 winter. Draughts may be felt inside
underground systems, particularly
when they blow through narrow
galleries from one part of the cave
to another.
Another great difference between
the inside of a cave and the
outside is the composition of the
atmosphere: inside a cave it is
highly variable, while outside it is
much more constant.
What changes significantly is the
amount of CO2 which, in ordinary air,
is normally between 1 and 3%,
whereas inside a cave it may be up
to 100 times greater. These values,
which are due to biological activity in
the soil and water transport, vary
according to season and type of
cave development, but they are inany case within our tolerance range.
Only rates exceeding 10% of CO2are dangerous: they are found in the
lowest layers of some volcanic
caves or ones in which hydrothermal
fluids are present (the phenomenon
was known even in the 18th century
in the Grotta del Cane at Pozzuoli,
near Naples).
Breathing problems arise in some
caves which are, or were, affectedby sulphur exhalations: examples
are the Grotta Azzurra and Grotta di
Cala Fetente at Palinuro (Campania)
and Grotta del Dragone at Maratea
(Basilicata).
For instance, sulphobacteria present
in water greatly reduce the contents
of the oxygen in favour of other
Cave deposits Paolo Forti Giuseppe Muscio
Eccentric concretions of aragonite and calcite
Concretions of barite
Concretion of sulphur and gypsum flakes
8/3/2019 01 Caves Karstic Phenomena 1
17/41
Mineralizations
About a hundred years ago, known
secondary cave minerals numbered less
than 45, for two main reasons: except for
calcite, aragonite and gypsum, which
alone make up more than 99.5% of all
cave deposits, other secondary minerals
are very rare, scattered, and difficult toobserve. However, they now number more
than 260 and new ones are found every
year. By cave mineral we mean a
secondary mineral which formed in a cave
and resulted from a chemico-physical
reaction which involved one or more
primary minerals existing in the rock or in
physical and/or biological deposits inside
the cave itself.
These rigorous limitations are necessary
to avoid secondary cave minerals being
considered together with all minerals
existing in nature. Caves are not generally
environments particularly favourable tominerogenesis, and very many caves do
not contain any secondary minerals at all.
But they may contain a large variety of
rocks: limestone, dolomia, gypsum, rock-
salt, quartzite, basalt, etc.. Their chemico-
physical degradation brings to the system
a large number of ions which may be
deposited as secondary mineralizations.
In addition, speleogenetic evolution may
cause primary mineralizations to outcrop
on cave walls which, in contact with
percolating waters or atmospheric
oxygen, may give rise to new chemical
compounds. Lastly, caves may contain
deposits of clay, guano, bones, etc.,
which in turn bring in ions which produce
further secondary minerals.
On this great variety of substrates, waters
of various origins - meteoric, marine,
thermal - with very different contents of
dissolved salts, in terms of both quality
and quantity, then act on this great variety
of substrates. In special cases, it may not
even be water which acts directly, but
other fluids, such as fumarole fluids in
volcanic environments.
The complexity of substrates and the
variability of water chemistry, combined
with the great differences in temperature
which may exist in caves, give rise to alarge number of phenomena and
potentially active minerogenetic
mechanisms. Some of these act in all
types of caves and over a wide
temperature range; others are only active
in special types of caves or need
particular temperatures in order to
become active. So it is not surprising that
many minerals were observed for the first
time in cave environments. Just one
example is that of francoanellite, a
phosphate found for the first time in the
cave of Castellana and named after the
famous Italian speleologist Franco Anelli.Nine minerals are still today exclusive to
the cave environment.
The scientific importance of cave
deposits
Of all cave sediments, chemical ones and
in particular concretions of calcium
carbonate are highly flexible and powerful
instruments for paleo-environmental and
paleoclimatic reconstructions. This is
because, as they grow, they incorporate
various trace minerals, fragments
transported in suspension during floods,
dust carried in by air currents, and organic
material, varying from molecules of humic
acids to spores and pollens. The laminate
and necessarily ordered structure of
concretions immediately provides a
relative chronological reconstruction of
the events corresponding to each single
growth band. Then there are a series of
methods which, more or less easily,
furnish an absolute chronological scale.
Thus, by analysing in detail the evolutionof stalagmites, we can gain information on
large-scale earthquakes over the last
500,000-600,000 years, and improve our
assessments of seismic risk. Data on the
deposition temperature of concretions
and on t he conditions and mechanisms of
their formation can lead to detailed
paleoclimatic and paleo-environmental
reconstructions, providing much
information on how climates evolved and,
for example, what the landscape must
have looked like in the second half of the
Quaternary era. For instance, thanks to
concretions in coastal grottoes (both
emerging from the water and submerged)
around Palinuro (province of Salerno,
southern Italy), we can date the variations
in sea level in that sector of the Tyrrhenian
Sea over the last few thousands of years.
Thanks to measurement stations located
in caves, we can quantify movements
connected with neotectonic phenomena.
A flowing water
B dripping waterC capillary waterD water in solution pansE water forming by condensationF warm rising water
1 flowstone
2 draperies, curtains
3 column
4 drop stalactite
5 hollow stalagmite
6 curved stalactites7 moonmilk8 disc-shaped forms9 macrocrystalline eccentric forms
10 inflorescences11 microgours12 pisolites13 boxwork14 rims15 geysermites16 rounded concretions17 encrustations18 mud stalagmites19 large crystals
3332
12
3
4
5
67
9
814
10
15
12
11
16
1718
19
13
B
B
E
C
F
D
B
A
A
Paolo Forti Giuseppe MuscioCave deposits
8/3/2019 01 Caves Karstic Phenomena 1
18/41
34
compounds (mainly H2S): while there are no problems in areas well connected
with the outside world, with good air supply, special attention must be paid
further inside.
Neglecting this phenomenon has cost the lives of more than one speleo-diver.
Karstic areas and the major subterranean systems in Italy
Italy occupies a prominent position both in the field of cave study and in more
purely exploratory activity. This is for historical reasons, and because karstic
phenomena are so widespread in Italy: 27% of the territory is composed ofkarstifiable rocks, and well st ructured and highly developed research on caves
has been going on for more than a hundred years. The various regional
registries list more than 33,000 caves, which is a somewhat low percentage of
those actually present in Italy: for example, the cave registry of Friuli-Venezia
Giulia contains more than 6,300 caves over an area of about 7,800 sq.km., and
every year this number increases by about 200 new entries.
There are as many as 180 subterranean systems in Italy (1999 data) which
exceed a depth of 300 metres, and of these six even exceed the threshold of
A
C D E
B
6C
20C
4C
2C
18C16
C
Grotta del Dragone at Maratea (Basilicata)
Air circulation in natural c aves: wind tunn el in summer (A) and winter (B); cold (C) or warm (D) airtrapped; in caves with only one opening, air circulation depends on atmospheric pressure (E)
35
8/3/2019 01 Caves Karstic Phenomena 1
19/41
36 1000 metres. The record depth is that of the Abisso Paolo Roversi in the
Apuan Alps, which goes down as far as -1250 metres.
There are 92 caves (again, 1999 data) which exceed 3 km in length, of which
20 exceed 10 km. The longest Italian cave is the Corchia Complex (Apuan
Alps), more than 52 km long. This is quite a feat, but it pales when compared
with the length of the largest underground system in the world, the Mammoth
Flint Cave in the United States, with more than 500 km of galleries!
Comparing tables of the longest and deepest caves with cave registry entries,
we see that Friuli-Venezia Giulia and Veneto, which have 9% of karstifiableterritory, have more than one-third of known caves, and the same regions,
together with Tuscany, Piedmont and Lombardy, contain three-quarters of all
large Italian caves. These are the most important karstic areas (but it is also
true to say that they have been systematically studied for longer, and have
thus given rise to a greater quantity of data).
Piedmont and Val dAosta. The Val dAosta is almost totally composed of
metamorphic and magmatic rocks, so that it does not contain any karstic
phenomena of significance. However, Piedmont has some of the largest
karstic systems in Italy, mainly concentrated in two large areas of the Maritime
Alps, Marguareis and Mongioie.The Piaggia Bella complex opens in the Marguareis valley, and contains about
a dozen different caves which, taken together, form a subterranean network of
more than 35 km, reaching -950 m. Slightly further south is Labassa, a
downvalley continuation of Piaggia Bella, more than 14 km long and with a
maximum depth of -609 m. In the same massif, the Conca delle Carsene
complex extends for 13.5 km and reaches -759 m. The Abisso dei Perdus,
Abisso Scarasson, Abisso Cuore di Pietra, Abisso Libero, Abisso Ferragosto
and the Colle dei Signori Complex (partly in Italy and partly in France) all
exceed 500 m in depth.
In the Mongioie massif are the C1-Regioso complex (more than 6 km) and the
Grotta delle Vene (4.7 km). The Abisso Ngoro-Ngoro and Abisso M16 in ValCorsaglia both exceed -470 m. The Risorgente della Mottera has been
explored to a depth exceeding 600 m (14 km), almost as far as the karst
surface basin.
The largest cave open to tourists, near Cuneo in Piedmont, is the Grotta di
Bossea, also equipped as a scientific laboratory and well-known for its
remains of the cave bear Ursus spelaeus. The Grotta dei Dossi, near Mondov,
was one of the first Italian caves opened to tourists, being equipped to allow
them to visit in the early 19th century.
TO
AO
MI
GE
TS
TN
VE
BO
FI
AN
AQ
CB
PG
ROMA
NA
BA
PZ
RCPA
CA
Main karstic areas in Italy
LIMESTONE
AND DO LOMIAGYPSUM LAVA
37
8/3/2019 01 Caves Karstic Phenomena 1
20/41
3938 Lombardy. Under the plateau of Cariadeghe (Brescia) is one of the most
important karstic cave phenomena, the largest of which is the Omber en
banda al Bus del Zel, more than 15 km long and about 420 m deep.
The Bergamo mountains contain many karstic areas of great interest: the
Grotta Maddalena in Val Taleggio is about 10 km long.
From the exploratory viewpoint, of considerable potential are the caves
around Lake Como: the Tacchi-Zelbio complex at Piani del Tivano extends for
almost 10 km and the cave at Capanna Stoppani more than 8 km; the Bl-
Guglielmo complex reaches -557 m.The Grigne mountain group contains some of the deepest caves in Italy:
speleologists have descended the Abisso Viva le Donne to -1170 m and the
Abisso Capitan Paff to -795 m.
Almost at the border with Piedmont, near Varese, the Parco di Campo dei Fiori
is another karstic area of great potential: the Nuovi Orizzonti and Marelli caves
extend for almost 6 km, and the Abisso Schiaparelli goes down to -600 m.
Some karstic phenomena in the region were visited by illustrious personages
in ancient times: the intermittent spring of Torno (Como) was described by
Pliny the Elder in 50 A.D., and the cave of Fiumelatte and the Ghiacciaia di
Moncodeno (Como) were described by Leonardo da Vinci. The Ghiacciaia
(ice-box) was again described in minute detail by the Danish polymathStensen in 1627, in a letter addressed to Nicol Cosimo III, Grand Duke of
Tuscany.
Trentino-Alto Adige (South Tyrol). For geological reasons, the largest caves
are to be found in the southernmost area of the region. Although this territory
was the cradle of mountaineering, after much research around the 1930s,
karstic phenomena were only properly studied after the 1960s. One of the
largest Italian caves, Bigonda, is in the Trentino region, and runs for about 26
km in Valsugana, collecting the waters of the Asiago plateau, where the Grotta
del Calgeron (5.3 km) also opens.
Again in Valsugana are the still active complexes of Fosca and CastelloTesino. There are about 700 caves in the Brenta Dolomites and the adjacent
Gazza-Paganella group, including the Grotta di Collalto (5.2 km), Torrione di
Vallesinella, Abisso Popov, and Abisso di Lamar. In Val Daone, south of the
Adamello group, is the Aladino cave (7 km), and the Abisso di Val Parol (1.6
km, -430 m) opens in the northern slopes of Monte Baldo. Superficial
karstic phenomena are marked and widespread in the low Sarca valley and
on Mt. Baldo.
Lastly, explored only during the last 20 years are the karstic phenomena of the
Alto Adige (South Tyrol). Some very long caves have been explored in the
Marebbe plateau in the north-west of the region. Of great importance are the
remains of bears in the Grotta delle Conturines in the high Val Badia.
Veneto. With more than 6,500 registered caves, the Veneto is one of the Italian
regions in which karstism is not only extensive but also best studied. Apart
from small sectors in which magmatic or metamorphic rocks outcrop, the
entire mountain belt, made up of mainly carbonatic rocks, appears as a single
uninterrupted karstic area.The Lessini and Beric Hills, the plateaus of Asiago and Tonezza (Vicenza), and
Grappa, Montello and Cansiglio are all karstic areas par excellence, and
important pages in the history of Italian speleology have been written about
them. Although the Belluno area has practically been explored only in recent
years - with completely unexpected results - many Dolomitic mountains are
still totally unknown as regards karstism, and the Dolomites may be
considered a new frontier in Veneto speleology.
The Buso della Rana (in the Vicenza Lessini Hills) is the largest Veneto cave,
more than 25 km long, and it holds the record (which may soon be broken) of
being the longest Italian cave with only one entrance. The Busa di Castel
Sotterra near Montello is one of thelongest caves in the world in
conglomerates (more than 4 km). Two
large Veneto caves nearly reach 1000
m in depth: the Abisso di Malga
Fossetta in the Asiago plateau (-974
m) and the Piani Eterni complex in the
Vette Feltrine (-966 m). The Spluga
della Preta in the Verona Lessini Hills is
third on the list of large Veneto caves.
It remains symbolic for its exploratory
history, a true archetype and source ofhistorical knowledge, not only for the
Veneto but for the whole of Italian
speleology.
Friuli-Venezia Giulia. The Karst,
particularly near Trieste, was the cradle
of Italian speleology and, although
systematically researched for 150Grotta di Castel Sott erra (Montello, Veneto)
8/3/2019 01 Caves Karstic Phenomena 1
21/41
years, continues to supply new revelations. The density of known caves is
extremely high: 3,000 of them over a surface area of only 200 sq.km. And the
mystery of the subterranean course of the river Timavo has not yet been
completely solved. Among the best-known of the Carso caves is certainly
the Abisso di Trebiciano which, by means of a series of shafts, reaches the
course of the Timavo at a depth of more than 350 m.
The Grotta Skilan is the largest in the province, being more than 6 km long
and almost 400 m deep. The best-known cave in this area is certainly the
Grotta Gigante, one of the most popular with tourists. The Grotta GualtieroSavi extends for almost 4 km.
In Friuli, there are some interesting caves in the Julian Prealps, mainly
extending inside alternating carbonatic and flyschoid layers.
For this reason, most of them are horizontal: the Grotta Nuova di Villanova,
partly equipped for tourist visits, is more than 7 km long. Four km is the
length of the San Giovanni dAntro cave, which has at its entrance a small
church and Medieval fortifications
resting on other structures going back
to Roman times.
The Canin massif in the Julian Alps,
composed of Upper Triassic deposits,was the first high-altitude karst to
be systematically explored, and the
Col delle Erbe system (Abisso M.
Gortani and others), 880 m deep and
22 km long, was for many years the
deepest in Italy.
Now the area counts dozens of caves
exceeding -500 m (Foran del Muss
complex, -1100 m, 15 km; Abisso Led
Zeppelin, -960 m, Abisso Modonutti-
Savoia, -805 m, etc.). In the DevonianCalcari di Scogliera(limestone c liffs)
of the Carnian Alps is the Monte
Cavallo di Pontebbe complex, -690m,
which extends into Austrian territory.
In the Cretaceous limestone of the Carnian Prealps, the largest caves are
the Risorgiva di Eolo, more than 5 km long, and the various subterranean
systems of the Pradis area (La Val-Noglar-Mainarda complex, nearly 7
km). New zones of interest have been identified inside the Parco delle
41Dolomiti Friulane (e.g., Landri Scur
di Claut, 4.8 km).
Other interesting phenomena are
those of the Cansiglio plateau,
bordering the Veneto, where the Bus
de la Lum was explored between the
late 19th and early 20th centuries.
However, the most interesting feature
is the Gorgazzo spring, of Vauclusiantype (i.e., its waters entirely fill the
conduit), which collects the copious
waters from the plateau and which,
although starting at 47 m above sea
level, has been explored to a depth of
more than 100 m without the bottom
being reached. It is a very dangerous
cave, and several speleo-divers have
lost their lives in it. It is now explored
by means of small submarine robots.
Liguria. For its climate and geographic position, Liguria has many caves
with archeological and paleontological deposits, some of great significance.
At the frontier with France, the famous Balzi Rossi caves are among the
most important prehistoric sites in Italy. Equally interesting are the Toirano
caves, which may be visited by tourists. One curiosity is certainly the Grotta
del Treno di Bergeggi, which opens off a railway tunnel! In the limestone of
Mt. Tampa, near Giustenice (Savona) is the Grotta degli Scogli Neri (Black
Rock Cave), the longest in Liguria (almost 5 km). Near Finale (Savona) is the
Arma Pollera-Arma do Buio complex, two caves linked by a siphon. The
former cave is also an important prehistoric site.
At the frontier with France is the Grotta della Molesa (Imperia) which, at -253m, is the deepest in this area. Large-scale explorations are currently in
progress in the Balbiseolo cave (Bardineto), a downstream collector of the
Buranco Rampion: speleogists have already discovered almost 5 km of
galleries and are enthusiastic about future prospects.
Emilia Romagna. In the Appennines, a long but discontinuous belt of
Messinian and Triassic evaporitic deposits outcrops. Gypsum, hosting many
very interesting karstic phenomena due to its variety of environments,
40
One of the very many high-altitude shafts inMount Canin (Friuli)
Grotta Nuova at Villanova (Friuli)
8/3/2019 01 Caves Karstic Phenomena 1
22/41
4342 mineralogical aspect and insect fauna, does not contain many concretions
and thus is often not particularly attractive from the c lassical speleological
point of view.
The most interesting system is that of Spipola-Acqua Fredda, not far from
Bologna, more than 10 km long inside an area of such interest that it has
been established as a natural park. It is the longest cave in gypsum in
Western Europe.
The high valley of the Secchia (Reggio Emilia) contains extensive outcrops of
Triassic gypsum, in which karstism develops in underground meanders,i.e., watercourses penetrate evaporatic layers and then return, after an
underground course of greater or lesser distance, to their natural above-
ground beds.
The Fonti di Poiano are some of the most copious karstic springs in the
Appennines. The deepest gypsum cave in the world, the karstic system of
Mt. Caldina, with a difference in altitude of 265 m and a length of 1 km, has
recently been explored.
In the gypsum outcrops of Brisighella are the Abisso Fantini, Grotta della
Tanaccia, and Rio Stella-Rio Basino complex, one of the few fully protected
and conserved Italian caves.
Tuscany. Speleologically, Tuscany means the Apuan Alps: the Mecca of
cave exploration in recent years, but also one of the places where protection
of the subterranean world causes some of the most serious problems.
Many caves are threatened with destruction due to local quarrying for
Carrara marble, some of the highest-quality stone to be found anywhere in
the world.
The Abisso Paolo Roversi, more than 1250 m deep, conceals the Black
Hole, a single shaft more than 300 m deep and so wide that its walls cannot
be seen while speleologists descend it.
The Abisso Olivifer reaches -1215 m, and the Monte Corchia complex -
which, at more than 50 km, is the longest in Italy - goes down to -1190 m.The Saragato-Aria Ghiaccia complex is another of the small number of caves
exceeding -1000 m.
Of historical interest is the Tana che Urla (Screaming Lair), near
Fornovolasco. Although this cave is not particularly long, through it flows a
watercourse which was studied by Vallisneri during his work on
subterranean hydrology in the 18th century. In the same area is the Grotta
del Vento, open to tourists. The hydrothermal Giusti cave, near
Monsummano Terme, contains waters at a temperature of 35C.
Umbria and Marches. The Appennines in this area have extensive outcrops
of Mesozoic limestone. In the Monte Cucco massif is the cave of the same
name, 920 m deep and more than 31 km long.
But the most famous caves here are those of the Gola di Frasassi, not far
from Jesi. The Fiume Vento complex (more than 23 km) is one of the most
beautiful subterranean systems in the world: in part accessible to tourists,
more than 400,000 visitors come to admire it every year.
This is a cave in which recent works aimed at respecting as much as
possible the requirements of theunderground environment and above all
at safeguarding the peculiarities of its
microclimate. In the same area is the
Grotta di Frasassi, at the entrance to
which is a fascinating little temple built
in the early 19th century to a project by
the architect Valadier.
Abruzzo and Molise. Until now, the
carbonatic massifs of the Gran Sasso
and Maiella have only partially revealedtheir enormous potential. One example
is the Cavallone cave (open to tourists),
in which a keen nose can smell the
hydrocarbons present in the rock. Near
the city of LAquila is the Risorgiva di
Stiffe, more than 1.5 km long, open to
tourists. Larger caves are in the Matese,
a carbonatic complex south-west of
Campobasso, where the Pozzo della Neve reaches the respectable depth of
1045 m, and the Abisso Cul di Bove extends for almost 4 km.
Latium. The massif of the Monti Lepini hosts the Grotta del Formale (more
than 4 km) and the Abisso Consolini (about -600 m).
Other karstic areas of great potential are those in the Monti Aurunci, where
the Abisso Vallaroce reaches -565 m; Monti Ausoni, whose waters are
collected by the Pstena caves, more than 3 km (open to tourists); Monti
Simbruini, with the Grotta di Bellegra; and Monti Ernici, with the Abisso degli
Urli (-610 m, more than 3 km).
Some remains of Neanderthal Man were discovered in 1939 in the Grotta
Fiume Vento co mplex (Marche)
8/3/2019 01 Caves Karstic Phenomena 1
23/41
Puglia (Apulia). This is one of the regions where carbonatic rocks outcrop
most extensively. Three separate karstic macro-areas have been identified:
Gargano, Murgia, and Salento. Superficial forms are very widespread on the
Gargano promontory, which also contains one of the largest dolinas in Europe,
the Dolina Pozzatina, more than 600 m across and 100 m deep. The Pulo di
Altamura and Pulo di Molfetta lie on the Murgia plateau. Also of importance
are the Gravine, long karstic valleys which mainly cut the Murgia Tarantina
plateaus.
The best-known cave, the Grotta di Castellana, discovered by Prof. Anelli in1938, is today one of the most popular Italian caves open to tourists. The
deepest cave in the region is the Grava di Campolato (San Giovanni Rotondo),
more than 300 m deep. Many Apulian caves are interesting not only from the
purely speleological viewpoint, but are also of special importance for the
paleo-ethnological evidence they reveal. Examples are the Grotta Paglicci
(Gargano), frequented by man since Paleolithic times, Grotta dei Cervi at Porto
Badisco in Salento, and the Scaloria-Occhiopinto complex at Manfredonia,
used in Neolithic times for water worship. Of great significance is the recentdiscovery of human remains in the Grotta di Lamalunga near Altamura. Lastly,
mention must be made of caves used by man for purposes of worship: from
paleo-Christian until Late Medieval times, caves were lived in by hermits, used
as crypts, and even devoted to the cult of the Archangel Michael.
Unfortunately, much of the deep karstism in Apulia has been profoundly and
severely altered by man in modern times. As well as total destruction of caves
due to quarrying, there are abundant cases in which city sewage has been
sent into natural cavities. Very many caves have been used as dumps for all
4544 Guatteri on the Circeo promontory. Other caves of paleo-ethnological
interest also occur, mainly near Latina.
Campania. The Alburni massif was the first karstic complex to be
systematically explored in Southern Italy. Extensive karstic areas contain the
Grava dei Gentili (-484 m), Grava del Fumo, Grotta del Casone Vecchio, and
others.
At the foot of Monte Alburno is the Grotta di Castelcivita (open to tourists)
recently found to be linked with the active system (Ausino) of water collectionof the overlying massif, forming a complex more than 6 km long.
Grottoes, or sea caves, are of great importance: the best-known in Italy are the
famous Grotta Azzurra on Capri and that of Cape Palinuro. Again at Palinuro is
the Grotta di Punta Galera, more than 1 km long, crossing the narrow
promontory almost completely. Of particular interest is the fact that many of
the grottoes of Cape Palinuro have been, and partly still are, subject to the
circulation of sulphur-bearing fluids which was the main factor influencing the
formation of their cave deposits.
Interesting prehistoric sites are found in many caves between Palinuro and
Camerota. In the Cilento area is the underground course of the river Bussento
which, near Casella in Pittari and Morigerati, enters the carbonatic massif andleaves it again more than 4 km downstream. Until a few years ago, this stretch
of subterranean flow was used to transport sewage!
Grotta di Castellana (Apulia) Grotta di Porto Badisco (Ap ulia): wall paintings
One of several grottoes along Cilento coast (Campania). Note concreted paleosoils at entrance: manycaves were used by prehistoric man
8/3/2019 01 Caves Karstic Phenomena 1
24/41
4746 kinds of materials, sometimes even toxic waste. A significant example is the
Grava di San Leonardo (San Giovanni Rotondo), full of tons of expired
medicines and other hospital material, which could very easily pollute the
underlying water-table.
Basilicata. Near Maratea, in the narrow Tyrrhenian belt of this region, is the
Grotta del Dragone, with about 3 km of galleries, a fossil exit of the karstic
complex of Monte Coccovello.
Although there have been reports of exhalations which might have madeexploration dangerous, due to the presence of a waste dump in a dolina, the
problem now appears to have been solved. Particularly well developed here is
exploration of grottoes, and the Centro Europeo di Speleologia Marina is
located here.
Along the coast is the Grotta delle Meraviglie, partly open to tourists. Nearby,
at Trecchina, is the Grotta di SantAngelo, about 500 m long, full of decorative
concretions and fascinating details.
Also important is the Grotta di Castel Lepre near Marsico Nuovo (almost 2 km),
and even larger is the Grotta I Vucculi at Muro Lucano.
Particular mention must be made of the Matera area, where natural caves
were extensively used as dwellings for humans - in fact, some are stilloccupied!
Calabria. The Abisso del Bifurto in the Pollino massif reaches a depth of -683
m (once the Italian record). Another cave of interest is the Grotta di Serra del
Gufo.
On the Ionian side of Calabria are the Grotte di SantAngelo near Cassano:
described as long ago as 1571, they extend for more than 2 km and are linked
to a system of sulphur springs. Hot sulphur-bearing waters are exploited as
thermal waters in the Antro delle Ninfe near Cerchiara.
The Tyrrhenian side contains many caves of archeological interest. Near
Crotone is the Grotta di Samouri Tour, more than 2 km long, through whichan underground river flows.
Sicily. The carbonatic massifs of the island (Nebrodi, Iblei, Madonie) contain
the Grotta di Pantalica and many other karstic systems, but most
characteristic of all are certainly the lava caves, many of which open on the
flanks of Mount Etna.
The best-known is the Grotta dei Tre Livelli (more than 1300 m long, more than
300 m deep), but the presence - at the foot of a volcano - of a subterranean
glacier in the Grotta del Gelo (frozen cave) is truly out-of-the-ordinary. The
Abisso Profondo Nero has more than 1 km of galleries. The Sicilian
speleological potential is completed by caves in gypsum, like the well-known
Grotta di Santa Ninfa, with more than 1 km of galleries richly covered with
concretions, and SantAngelo Muxaro.
Mention must also be made of the Grotta di Monte Kronio at Sciacca. This is
an important prehistoric site, used in the past as a place of worship and now
practically closed to exploration, due to hot vapours which bring the internal
temperature to more than 38C. This cave can now only be visited with specialequipment.
Sardinia. Extensive outcrops of carbonatic rocks mean that Sardinia is one
of the most interesting areas for
speleologists, with often very long
horizontal caves decorated with
concretions.
In Supramonte di Oliena and around
Dorgali, there are large subterranean
systems like Su Bentu-Sa Oche (15
km) and San Giovanni Su Anzu (11km). But the largest is Codula de Luna,
formed of a join between Su Palu and
Su Spiria, more than 38 km long.
There are also many sea grottoes, very
popular with tourists, such as the
Grotta di Nettuno at Alghero and the
Grotta del Bue Marino at Dorgali.
Short history of speleology and speleological structure in Italy
A brief history of Italian speleology is extremely difficult - above all when werealize that, since the Second World War, Italy has been the country in which
this science developed most.
For thousands of years, caves were lived in and used for protection by man
and animals. Later, they were privileged places for religious or pagan rites, and
have always been treated with respect - perhaps with more fear by Medieval
people than by prehistoric man, who transformed sometimes highly
inaccessible caves into true temples of art (e.g., Grotta dei Cervi, at Porto
Badisco in Apulia).
Grotta di Santa Barbara (Sardinia)
8/3/2019 01 Caves Karstic Phenomena 1
25/41
8/3/2019 01 Caves Karstic Phenomena 1
26/41
5150 Bologna, mainly as a tool for
scientific research, which published
a few numbers of the Rivista Italiana
di Speleologia. But the moment
was not yet right for national
coordination of speleology, which
passed through a period of dualism
between exploration and research.
Although the First World War greatlyaffected many associations (for
instance, the Circolo di Udine
emigrated to Florence after the
defeat of Caporetto), it did lead at
last to the conquest by Italy of all
the classic Karst territory, enabling
Friuli-Venezia Giulia to maintain its
position of speleological pre-
eminence on a world scale. But
gradually successful explorations
throughout North Italy followed:from the Abisso Bertarelli (Karst; -
450 m), to the Spluga della Preta
(Veneto), the Abisso Guglielmo in
Lombardy, to the -541 m of the
Antro del Corchia in Tuscany,
reached in 1934.
At that time, limitations were
certainly not dictated by the
capacities of the explorers, but only
by logistic problems and the weight
of all the necessary materials whichhad to be transported into the
bowels of the earth. Explorations
which nowadays can be undertaken
in a few hours by a team of three
speleologists, at that time required
months of preparation, dozens of
men, and several days hard work
by the actual exploring team. These
problems, essentially the same, remained, although with improved materials and
equipment, until the 1970s, when new climbing techniques with advanced kinds
of ropes meant that transport of heavy materials could be greatly reduced while
safety measures were respected. And high-altitude caves could be explored, in
areas already well-known potentially by the fathers of modern speleology.
Returning now to the period between the two world wars, an essential role was
played by the Istituto Italiano di Speleologia, with headquarters in the Grotte di
Postumia, which created a Cave Registry, published the important review Le
Grotte dItalia, and coordinated exploration and research by various expertgroups. This favoured the development of speleology in Italy and its expansion
to the southern regions, but after the Second World War the assets of the
Institute were dispersed, the great speleologists of the past died, and Italy also
lost not only most of the classic Karst, but also its supremacy in the
speleological field.
The dense network of speleological associations started functioning again
around 1950, when the Societ Speleologica Italianawas founded in Verona,
viewed as an association for actively interested speleologists. A few years later,
Gortani re-established the Italian Institute of Speleology in Bologna, this time
focusing principally on scientific research: only after years of strained relations
did the two associations manage to agree.In the 1960s, partly thanks to improved techniques, new explorations were
undertaken, with the record for depth (-878 m) going to the Spluga della Preta
(Veneto). These were the years in which the Apuan Alps, Canin and Marguareis
were explored, still today the subject of constant surveys.
However, in the same years, several deaths occurred which led, among other
things, to the setting-up of the Speleological Rescue Service within the Alpine
Rescue Service.
In those years, speleology was only well-developed in some regions (Friuli-
Venezia Giulia, Piedmont, Emilia-Romagna, Tuscany) and was somewhat
restricted: there was a sort of distance, a coldness, between the two branches
of speleology, exploratory and academic. Fortunately, this state of affairsgradually subsided. Over the next few years, speleological structures and
organizations began to develop and, although each group maintained its
autonomy, regional federations were set up and all administrative bodies
followed the path opened in 1966 by the Friuli-Venezia Giulia Autonomous
Region which was the first to issue legislation for the protection of karstic
phenomena, support speleological activity, and officially constitute a Catasto
Grotte(Cave Registry). Now, almost all Italian regions have their own federations
and functioning cave registries, and more than 300 groups are active.Descent by rope ladder into Viganti shaft (1949)
8/3/2019 01 Caves Karstic Phenomena 1
27/41
53BiospeleologyLEONARDO LATELLA FABIO STOCH
Sphaeromides virei
Biospeleology in Italy
Origins. Initial interest in underground fauna in Italy goes back a long way:
already in the second half of t he 16th century the Vicenza-born Gian Giacomo
Trissino wrote to Fra Leandro Alberti, describing some tiny shrimps found inthe Beric Hills (he was speaking of amphipod crustaceans, now known as
Niphargus costozzae). But he was simply curious, he was not carrying out
scientific research. The first true mention of cave-dwelling animals was made
in 1689, when Baron Johan Weichard Valvasor spoke of a ptit dragon found
in a spring in Carniola. In 1768, Joseph Nicolaus Laurenti described it under
the name of Proteus anguinus, and set it in the group now called caudate
amphibians, although he did not recognize it as a true troglobite. The first
scientific description of an animal really living inside a cave was made by
Ferdinand Schmidt who, in 1831, described Leptodirus hohenwarti, a troglobic
insect found in the Postumia caves. It is perhaps from that date that science
made its official entry into the underground world.A long series of zoological studies began in the 1830s, aiming at knowledge of
cave-dwelling animals. And it was in the Postumia caves, open to visitors for
the first time, that the fulcrum of modern biospeleology may be said to rest.
The first scientific works on subterranean fauna were published in Italy in the
first half of the 20th century. Among these pioneering works were the studies
of Ruffo on cave-dwelling fauna in the Verona region in 1938, and those of
Denis on spring-tails in Italian caves in 1931. But a wealth of literature was
soon created, mainly from taxonomists who were rapidly discovering the
incredible variety of subterranean fauna. After approximately ten years of
inactivity, principally due to the Second World War, work began again with
renewed enthusiasm. The 1950s saw the works of Patrizi and Cerruti on cave-dwelling fauna of Latium and surrounding regions (1950) and Latium and
Sardinia (1953), of Conci on Venezia Tridentina (1951), Ruffo on Apulia (1955)
and Franciscolo on the Savona region (1955), to quote only a few of the most
important works of gen