Franklin_Canyon_Santa_Monica_Mountains

A Look at Franklin Canyon in the Santa Monica Mountains

Field Assignment

Lucia RodriguezGeology 103, LTCC

Professor Mark LawlerJuly 21, 2011

Content

o Geography & Mapo Overview of the Santa Monica Mountainso Geological historyo Climateo San Andreas Faulto Rock exampleso Florao Faunao References

2

Geography & Map 3

• I visited Franklin Canyon on a sunny day in mid July of 2011. • Franklin Canyon rests on 605 acres of land. It is one of the parks in the Santa Monica Mountain System, and it sits close to the South Eastern end of the system.

• On this presentation I will give an overview on the Santa Monica Mountains geology and environment, and specifically on Franklin Canyon, based on my observations and research.

Map courtesy of Mapquest

Map courtesy of Santa Monica National Recreation Parks

Overview 4

• Franklin Canyon is in the Santa Monica Mountains system, which is a part of the Transverse Ranges. The transverse ranges sit on top of the colliding North American and Pacific Plates.

• Geographically, the Santa Monica Mountains run along the

Pacific through Los Angeles and the San Fernando Valley.

• Climate is Mediterranean and ecosystem is rare and wide in variety.

• Vegetation consists of chaparral, grasslands and oak woodlands. There is a three-acre lake, a duck pond and over five miles of hiking trails. (LA Mountains, 2011)

• The Santa Monica Mountains have lived through many fires, due to the chaparral and coastal sage brush.

• These mountains are 46 miles long and eight miles wide. Volcanic Sandstone Peak, at 3,111 feet above sea level is the highest point in the park. (National Parks Service, 2011)

Geological history

• About 16 million years ago the Santa Monica Mountains

started to emerge from the ocean. Much volcanic activity took

place and the Mountains continued to grow for the next 3

million years, reaching 10,000 feet high. (National Parks Service

2011).

• The range contains rock 154 to 200 million years old.

Transverse ranges of Southern California Mountainsrun in an East-West direction instead of North-South. There is faulting, uplift, and erosion which is all taking place now. • There has been periodic uplift in the area since the Oligocene collision of the Pacific and the North

American Plates. The rocks exposed date from the Jurassic to the Quaternary.

• Santa Monica Mountains National Recreation Areacontains one of the most diverse fossil assemblages of

fossilwith at least 2,300 known fossil Localities. (Santa

Monica Mountains National Recreation Area, 2011).

Unfortunately I wasn’t lucky enough to find one.

Photo courtesy of National Parks Service

5

Geological make -up

Chart courtesy of The Santa Monica Mountains National Recreation Area.

This chart shows the diverse make-up in the geology of these mountains, including extensive areas of volcanic intrusions, and recent sediments (in red and grey, respectively).

The range was created by repeated episodes of uplifting and submergence by the Raymond Fault that created complex layers of sedimentary rock. There are thick marine sedimentary sequences of sandstone, siltstone, and mudstone, as well as volcanic deposits.

6

Climate

• With a chaparral biome, there is a very wet winter and also a very dry summer. The summers can be dry enough to create a drought, and this dry period can extend for up to five months out of the year. These dry conditions make the risk of fires breaking out very high.

• Many of the plants found in the chaparral biome have leaves that are made from highly flammable materials. That is why the fires are able to spread so quickly rather than just from the dry conditions. Those are also the plants that have the ability to withstand the fires. They have heavy bark and deep roots so it isn’t long after the fire that they are able to thrive again. (Bio expedition, 2011)

7

San Andreas Fault

San Andreas fault. Photo from waterencyclopedia.com

• The Santa Monica Mountains sit in the midst of several faults. The largest by far is the San Andreas Fault, caused by the collision of the North American and the Pacific Plates, which move in opposite directions. • Besides the constant change in its environment due to fires and its volcanic history, here is another aspect that makes this range so interesting and constantly mobile.

• Uplift of the Santa Monica Mountains continues today at a gallop: one inch every thousand years. (Collier, 1999)

8

Rock example #1

• Basalt is a common extrusive, igneous, mafic rock. Extrusive or volcanic rocks form from lava, which cooled on the Earth's surface.

• We know that the ocean crust is predominantly composed by basalt.

• This rock may have arrived here in different ways. It could possibly be the result of the many volcanic eruptions that took place over time, or it might have been exposed from the ocean crust in the collision of plates.

9

Rock example #2

• Sandstone is a Clastic Sedimentary rock (also called terrigenous or detrital) • Fragments of sediment laid down by water or wind become compressed or cemented over time.

• They tell us the locations of ancient sedimentary environments such as seas, reefs, deltas, beaches, rivers, lakes deserts, glaciers, and mountains.

• As you can see on the photo, leaves are already becoming part of this sedimentary rock.

• Sedimentary rocks contain the fossil record, which preserves the evolving story of life on Earth over the eons. Unfortunately I didn’t run into any fossils on my trip, but I was able to find an example from the Santa Monica Mountains (see photo on the right, below.)

Photo courtesy of National Parks Services

10

Flora

• I encountered a lot of examples of the Chaparral flora, as well as a lot of conifers (gymnosperms), sycamores, oaks, and a wide

variety of flowers , including what I believe was a California yucca (perennial shrubs and trees in the family of Asparagaceae, see

below) which I later learned is a cousin of the Joshua tree (Wikipedia, 2011) • The chaparral biome is one that is found in areas of every single continent, many people don’t realize it is

the same. A chaparral biome is created when cool water from an ocean merges with a landmass that is at a high

temperature. The major chaparral biomes are found along the coast of Baja and California. They are also found in various areas around the Mediterranean Sea. (Bio expedition, 2011)

11

Flora example #1 – The Sacred Datura

• The Sacred Datura (Datura wrightii) is a vascular plant, herbaceous perennial belonging to the Solanaceae family. It is poisonous and sometimes used as a hallucinogen. Its flower is divided in five symmetrical lines and it is usually white or purple.

• Datura is found in desert areas, in coastal sage scrub, and in joshua tree woodland.  It is very common and blooms from April to October. (Calflora, 2011)

• Vascular plants evolved before the Middle Silurian, some have been found from Middle to Upper Ordovician rocks.

12

Fauna

Fauna that populates the Santa Monica Mountains include:• Birds: Mandarin ducks (migratory birds), hummingbirds, etc. • Mammals: Deer, bobcats, mountain lions, squirrels, etc. • Amphibians: Pacific tree frog, salamanders, toads, etc. • Insects: Swallow-tail butterflies, bees, etc. • Reptiles: lizards, rattlesnakes, turtles, etc.• Fish: Californian grunion, kelpfish, etc. • More than 450 vertebrate species occur in the park. The relatively intact wildlife is impressive

considering their proximity to one of the largest urban areas in the United States.”(National Park Service, 2011)

I ran into a good amount turtles and koi fish in the pond. I learned later that the pond was man-made, so for the purpose of this presentation I looked at other examples of native fauna.

13

Fauna Example #1: The Pacific Rattlesnake

• Fortunately (or unfortunately), I didn’t run into a rattlesnake on this trip, however I have, many times in past hikes and I would like to present it briefly.

• Rattlesnakes are dangerous, but important to our environment; without them, rodent populations would rise causing an imbalance in the ecosystem. Rattlesnakes seek areas in their body temperature range from 64 to 89 degrees (McAuley, 1990), which means they show up mostly in the heat of the summer.

• The Pacific Rattlesnake or Crotalus oreganus is a reptile of the Viperidae family. Reptile diversification began during the Mississippian Period. From this basic stock of so called stem reptile, all other reptiles (as well as birds and mammals) evolved. (Monroe and Wicander, 2006)

Picture courtesy of Ken J. O’Brien

14

Fauna Example #2: The Squirrel

• Squirrels are small and they live in almost every habitat from the rainforest to the desert. Squirrels' diet consists of a wide variety of plant food, including nuts, seeds, conifer cones, fruits, fungi and green vegetation. (Wikipedia, 2011)

• The squirrel is a mammal of the Rodentia order, and the Sciuridae family.

• It evolved from the Therapids, in the Permian Period, from which all mammals evolved. Then in the early Cretaceous, mammals diverged into two branches: triconodonts and monotremes. Monotremes include marsupial and placental mammals, the squirrel is a placental mammal. The divergence of marsupials and placentals may have taken place in the Early Cretaceous but undoubtedly both were present by the Late Cretaceous. (Monroe and Wicander, 2006)

Squirrel next to the pond, July 2011

15

References

o Monroe, J. S. , & Wicander, R. The Changing Earth: Exploring Geology and Evolution. (2006)o Jaffe, M. , and Gamache, T. The Santa Monica Mountains: Range on the Edge. (2006)o Los Angeles Mountains. (2011). Retrieved from: http://www.lamountains.com/parks.asp?parkid=14o National Parks Service. (2011). Retrieved from: http://www.nps.gov/samo/naturescience/

naturalfeaturesandecosystems.htm, (retreived from: http://www.nps.gov/samo/naturescience/animals.htm)

o The Santa Monica Mountains National Recreation Area. (2011). Retrieved at: www. http://www.nps.gov/samo/naturescience/geologicformations.htm

o Bio Expedition. (2011). Retrieved from: http://www.bioexpedition.com/chaparral-biome.htmlo Collier, M. A Land in Motion: California’s San Andreas Fault. (1999)o Wikipedia. (2011). (Retrieved from: http://en.wikipedia.org/wiki/Yucca) (Retrieved from:

_http://en.wikipedia.org/wiki/Squirrel)o Calflora. (2011). (Retrieved from: http://www.calflora.net/bloomingplants/sacreddatura.html)o McAuley. Guide to the Backbone Trail. (1990)

16