Transcript
Introduction to Earth Science
Chapter 1
Biogeosciences
Earth sciences today incorporates biology.Some once thought to be inorganic processes
may in fact be geochemical……….Bacteria have been found everywhere there is
water, including the tiny pore spaces between mineral grains. Many minerals are made by biological processes.
Find some examples…………EXTRA CREDIT OPPORTUNITY
Earth Science is………
The name for the group of sciences the deals with Earth and its neighbors in space.
1. Geology – “study of Earth”
a. physical geology – includes the materials and processes that shape the Earth.
b. historical geology – tries to establish a timeline for the vast number of physical and biological changes that have occurred in the past.
Oceanography – integrates chemistry, physics, geology, and biology.
a. Composition and movements of seawater, coastal processes, seafloor topography, and marine life
Meteorology – The composition of Earth’s atmosphere.
a. Earth’s motions and energy from the sun cause the atmosphere to produce different weather conditions. This in turn, creates the basic pattern of global climates
Astronomy – is the understanding of Earth’s position in the universe.
a. Learning about other members of our solar system and the universe may help us understand Earth.
How do you think the Earth formed? Catastrophic – The earth formed rapidly in
a series of “catastrophic” events. This occurred approximately 4.56 billion
years ago………What are some catastrophic events?Volcanic events, earthquakes, tsunami,
asteroid impacts.You must ask yourself… What kind of impact
do these events have?
Another Possibly
Uniformitarianism – The earth formed over a long period of time through the geologic process at work in the world today…….
Plate tectonics or continental drift is a example of a slow continuous process.
As It Turns Out
Both theories were part correct….
The earth probably did form quickly, but cooled slowly and continuously since that time.
A Closer Look… at the Solar System.. Protoplanet Hypothesis
What kinds of things does the solar system have in common..
1. All planets orbit the sun in the same direction (counter-clockwise)
2. Most planets have moons that orbit their planets in the same direction (counter-clockwise)
3. Most planets rotate the same direction (counter-clockwise)
4. The sun rotates in the same direction as the planets rotate
What does all this mean?
Formation of Earth
Nebular hypothesis – suggests that the bodies of the solar system evolved from an enormous cloud called the solar nebula.
This cloud was made of mostly hydrogen and helium with a small percentage of heavier elements
What Happened Next….
High temperatures and weak gravity characterized the inner planets. As a result they could not hold onto the lighter gases in the nebula.
The lighter gases hydrogen and helium were whisked away to toward the heavier planets by the solar wind.
Earth, Mars, and Venus were able to hold some of these heavier gases including water vapor and CO2
The outer planets have water vapor, CO2, ammonia, and methane.
Earth’s Place in the Universe
In the 1900s Edwin Hubble demonstrated that the Milky Way is one of perhaps hundreds of billions of galaxies in the universe.
How old is our universe?
Between 13 & 14 billion years old
How do we think the universe formed? It formed from a dense, hot mass that
violently exploded. Within seconds the temperature of the
expanding universe cooled 10 billion degrees.
Basic atomic structures formed like protons and neutrons.
After a few minutes simple atoms of hydrogen and helium formed.
Layers form on Earth
Shortly after the Earth formed radio active elements combined with heat released from colliding particles, produced some melting of the interior.
This allows heavier elements like iron and nickel to sink.
The lighter rocky components floated to the surface.
This differences in density allowed a layering to occur with each layer having its own properties.
Gases escaped the surface much like with volcanic eruptions today.
The atmosphere as well as the oceans formed from gases that were released from within the the Earth.
Earth’s Major Spheres
1. Hydrosphere
2. Atmosphere
3. Geosphere
4. Biosphere
Hydrosphere
All the water on the Earth 97% of all water is salt water 3% is freshwater
– 2% of the freshwater is locked up in ice– 1% of the freshwater is usable
Atmosphere
90% is within 16 kilometers of the surface Importance:
– Breathable air– Protection from the sun’s intense heat and
radiation– Weather and climate patterns– Weathering and erosion
Geosphere
Is not uniform, is divided into three main parts based on composition– Crust – (lithosphere) least dense layer.
• Continental crust
• Ocean crust
• Asthenosphere – partially molten, this allow the pieces of the crust to flow
– Mantle
– Core – most dense layer• Outer core
• Inner core
Biosphere
It extends from the ocean floor to several kilometers above the Earth’s surface
Plants and animals depend on this biosphere Organisms help maintain and alter their
physical environment
A Dynamic Planet
Earth’s ever changing surface Two types of forces
– Destructive forces - weathering and erosion– Constructive forces – volcanism and mountain
building
Plate Tectonics This theory provided scientists with a model to
explain how earthquake and volcanic eruptions occur. How continents move.
The lithosphere is broken into sections called plates.
The plates move as a result of unequal distribution of heat within the Earth.
This movement of the plates generates earthquakes, volcanoes, and forms mountains.
Plate Tectonics
There are two types of forces that affect the Earth’s surface.
1. Destructive forces – like weathering and erosion. These forces tend to flatten the surface of the Earth
2. Constructive forces – volcanism and mountain building. These build up the surface of the Earth and in some cases from new land. These forces are driven by the Earth’s internal heat.
The Model
The theory that emerged, called plate tectonics, provided geologists with a model to explain how earthquakes and volcanic eruptions occur and how continents move.
Representing Earth’s Surface
How do we determine our location on the Earth?
We use 2 measurements
1. latitude - is the distance north or south of the …………..
equator and is measured in degrees
2. longitude – is the distance east or west from the
prime meridian and is measured in degrees
Lines of latitude and longitude form a global grid.
The Need for Maps……..
Globes are great, but………
Maps – are flat representations of the Earth’s surface.
No matter what kind of map is made, some portion of the surface will always look to small, to large, or out of place.
Map makers have found ways to limit the distortion.
Mercator Projection
Geradus Mercator, (1569)
His map was designed for use by sailors. It is great for navigation, but distorts sizes of landmasses.
Robinson Projection
Widely used Shows most distances and sizes without
much distortion
Conic Projection
Only the lines that touch the cone are accurate.
Good for making road and weather maps
Gnonomic Projection
Distances and directions are distorted
Good for short or straight line navigation at sea and when flying.
Topographic map
Represents the three dimensional Earth on a two dimensional map.
These maps show elevation by means of contour lines.
Topographic map terms
Contour interval – determines the distance between contour lines.
Index contour – darker in color they represent 100s of feet
Scale – distance measure made to scale with the land surface
Depression – a hole in the ground Declination – difference between true north and
magnetic north
Topographic Maps
Are designed to show the “ relief “ of the land ( shape of the land ).
They are made to a scale.Smaller scaled maps show
greater detail
Maps Scale
Map scale is a ratio
1:52000 means?1 inch on the map = 52000 inches on
the ground
Map Scale
Topographic Map ColorsBrown - Contour lines
Thick Brown - Index contour lines
Black - Man made objects
Green - vegetationRed - some roads
Blue - water
Contour lines
Vegetation
Road
Man made
Water
STEEP SLOPE
GRADUAL SLOPE
Hill top
Hill top
Valley
ValleyValley
Actual surveyed spotgives latitude, longitude and elevation abovesea level
Map Scale
Tenths of a mile0
Declination
the angle of difference between magnetic north and true north.
Contour linesThe distance between
contour lines is the contour interval.
It is printed under the map scale on the bottom- center of each map.
They are measured from sea level
Calculating average slope
Ave. slope = change in elevation (ft.) distance (mi)
Ave. slope = 1060 ft – 960 ft = 100ft = 25 ft/mi 4 mi 4 mi
1210 ft.1160 ft. south or S-E
144.4 ft./mi.
Steep slope
1190 ft.
S-E
1170 ft.
1270 ft.
920 ft.
Geologic Maps Show types and ages of rocks exposed on
the Earth’s surface.
Advanced Technology
Satellites for remote sensing, GPS devices, etc.
Earth System Science
The Earth is seen as being dynamic planet with separate but interactive parts or spheres which are also interconnected.
Each interactive and interconnected sphere is a subsystem…..
EX: geology, physics, chemistry, biology, etc. Earth needs to be seen as a whole and not
separated from its subsystems.
What is a System
Can be any size group of interactive parts that form a complex whole.
Most natural systems are driven by sources of energy that move matter and/or energy from one place to another.
EX: Cooling system of a car. This is a closed system. Energy moves through the system and eventually out. No matter enters or leaves this system.
Most natural systems are open systems.
Both energy and matter flow into and out of the system.
Ex: A river system… the amount of water flowing changes all the time as well as the water temperature and even the ground temperature.
Earth as a System The Earth system is powered by two heat
sources…….1. the sun …this powers the atmosphere,
hydrosphere at the Earth’s surface.2. interior heat produced by radioactive materials
and frictionThe parts of the Earth system are linked so that a
change in one part can cause changes in another part or even the whole Earth.
Ex: A new volcanic island forms… What are the changes that can happen?
Human Effect
Burning fuels Getting rid of wastes Construction
The list is almost endless.
People and the Environment
The environment is everything that surrounds and influences and organism.
These influences can be both living and non-living factors…Name some?
All this comes under the heading of environmental science.
Environmental science is used for things that focus on relationships between people and the natural environment.
Resources
Include:
Water
Soil
Metallic and non-metallic minerals
Energy
Resources divided into 2 categories
Renewable – can replenish over a short period of time.
Ex: plants, animals and their products, water, wind for energy.
Nonrenewable – iron, aluminum, copper, other minerals, also fossil fuels.
The processes that form these are very slow perhaps millions of years.
Environmental problems May occur locally or regionally They include significant threats to the
environment which includes:Air pollutionSoil pollution and lossNatural hazardsAcid rainOzone deletionGlobal warming
What is Scientific Inquiry?
All science is based on two assumptions:
1. the natural world behaves in a consistent and predictable manner.
2. Through careful, systematic study, we can understand and explain the natural world’s behavior.
Developing New Scientific Knowledge Requires….. Gathering data through observation and
measurement. Forming a (n) hypothesis – this is a possible
explanation . Testing the hypothesis… If found to have merit
then…. Form a theory – which has been tested and widely
accepted by the scientific community and best explains certain observable facts.
This is the basis of the scientific method.
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