Download Earth Systems and Resources

Earth Systems and Resources
10-15 % of your APES Exam
Geologic Time
• Based on layering of rocks and evolution of life
• Also based on radiometric dating
• Eon-> Era-> Period-> Epoch-> Stages
Geologic Time
• Rock Layers (strata) are laid down in
succession with each strata representing a
“slice” of time
• The principle of superposition- any given
stratum is probably older than those above it
and younger than those below it.
Geologic Time Scale
• Several factors complicate things…
– Sequences of strata are often eroded, distorted,
tilted or inverted after deposition
– Strata laid down at the same time but in different
places can have different appearances
– Strata of any given area can represent only part of
Earth’s history.
Earth’s Structure
• Formed 4.6 billion years ago
• Includes
– Biosphere- all life on earth
– Hydrosphere- all water on earth
– Internal structures…
Crust
• Crust makes up 0.5% of Earth’s mass
• Ocean- basalt (contains minerals rich in
heavier elements such as Iron, relatively
uniform)
• Continental- granite (much thicker composed
of volcanic, sedimentary and metamorphic
rock- very stratified)
The Rock Cycle
• Igneous- Formed by cooling and classified by silica
content. Intrusive igneous rocks solidify deep
underground and cool slowly and have a large grained
texture (granite) Extrusive igneous rocks solidify on and
near the surface and have a small grained texture
(basalt)
• Metamorphic- formed by intense heat and pressure.
Ex: Diamonds, Marble, Asbestos, Slate, Coal
• Sedimentary: formed by piling and cementing of
various minerals overtime in low-lying areas. Fossils
form ONLY in sedimentary rocks
Rock Cycle
MOHO, Mantle and Core
• Mohorovicic Discontinuity- boundary between
the crust and mantle.
• Mantle- composed of iron, magnesium,
aluminum and silicon-oxygen compounds.
Upper third is the plastic asthenosphere
• Core- composed of iron- Inner core is solid
Plate Tectonics
• Theory of plate tectonics comes from 2
observations: continental drift and seafloor
spreading
The Continental Drift Theory
• In 1915, Wegener proposed that continents came from
one giant land mass (Pangea). Based his theory on 5
factors
• 1. Fossilized tropical plants discovered beneath
Greenland’s Ice caps
• 2. Glaciated landscapes occurred in the tropics of Africa
and South America
• 3. Tropical regions on some continents had polar
climates in the past, based on paleoclimatic data.
• 4. Continents fit together like a puzzle
• 5. Similarities existed in rocks between east coasts of N
and S America and west coasts of Africa and Europe.
Seafloor Spreading Theory
• In the 60’s alternating patterns of magnetic
properties were discovered in the rocks on the
sea floor on either side of mid-oceanic ridges.
• Dating the rocks indicates that rocks got older
the farther away from the ridge. This suggests
that new ocean floor was being made at the
volcanic rift zones
Transform Boundaries
• Occur when plates slide past each other
• This friction and stress build up causes
earthquakes
• Example: San Andreas Fault in California
Divergent Boundaries
• 2 plates slide apart from each other with the
space created filled in with molten lava
• Create massive fault zones in oceanic ridge
system and areas of frequent oceanic
earthquakes
• Examples: Mid-Atlantic Ridge and East Pacific
Rise in the ocean. East African Great Rift Valley
in the continents.
Convergent Boundaries
• 2 plates slide toward each other commonly
forming a subduction zone (one plate moving
under the other, usually the more dense
ocean plate goes under the continental plate).
• Or they form a orogonic belt if the 2 plates
collide and compress.
• Examples: Cascade Mountains
Convergent Boundaries
• When 2 ocean plates collide they create and
island arc- a curved chain of volcanic islands
rising from the deep sea floor and near a
continent. The curve is usually convex toward
the open ocean.
• A deep undersea trench is located in front of
such arcs.
• Example: Japan and Aleutian Islands in Alaska
Convergent Boundaries
• When 2 continental plates collide mountain
ranges are made because crust is condenses
and pushed upward.
• Example: northern margins of the Indian
subcontinental plate being thrust under a
portion of the Eurasian plate, lifting it and
creating the Himalayas.
Earthquakes
• Occur during abrupt movement on an existing
fault along a tectonic plate boundary zone or
along mid-oceanic ridges.
• Massive amounts of stored energy are released in
a short period of time.
• The area where the energy is released is called
the focus
• The area directly above the focus is called the
epicenter
• The strength/magnitude of an earthquake is
measured on the Richter scale
Earthquake Case Studies
• Haiti, 2010
– January 2010- Magnitude 7.0 Earthquake
occurred at a depth of about 8 miles.
– International Red Cross estimates that about 3
million people were effected. 200,000 killed.
250,000 injured.
– Quake happened at the northern boundary of
Caribbean tectonic plate
Earthquake Case Study
• San Andreas Fault
– Transcontinental fault that extends 800 miles
– Pacific Plate and North American Plates
– Slippage is about 1.5 inches per year
– 1906 earthquake occurred near San Francisco
(7.8) causing 3,000 deaths.
Tsunamis
• Series of waves created when a body of water
is rapidly displaced usually by an earthquake
• Subduction zone tsunamis are most common
• Small wave-height and very long wave length
off shore- don’t notice them at sea
• In 2004 the Indian Ocean, 9.3 earthquake
created a tsunami that killed about 300,000
people- said to be one of the deadliest natural
disasters in history.
Volcanoes
• 95% occur at subduction zones and midoceanic ridges
• 5% occur at hotspots where plumes of magma
come close to the surface.
• Volcanoes produce ejects (lava rock and/or
ash), molten lave and toxic gas
Volcanoes
• Affect the climate by introducing large quantities
of Sulfur Dioxide that is converted to sulfate ions
in the atmosphere.
• These particles reflect shorter wave lengths of
solar radiation and serve as condensation nuclei
for high clouds
• Mt. Pinatubo erupted in 1992 and decreased
average global temperature 1 F because of the
sulfate particles in the stratosphere
• Particles take about 2 years to settle out and are
a big cause of acid rain.
Volcanoes
• How to deal
– Modeling and data analysis for better volcanic
activity prediction
– Better evacuation plans
– Study of precursors such and changes in the cone
– Measuring changes in temperature and gas
composition
– Magnetic changes
– Changes in seismic activity (correlation between
seismic and volcanic activity)
Volcano Case Study
• Mount Saint Helens:
– Located in Washington State- erupted in 1980
removing trees and increasing soil erosion.
– Destroyed wildlife, polluted air with gases and ash
– Increases mudflows and melting of glacial ice and
snow
– Clogged rivers that created flooding problems
– 57 people killed
Volcano Case Study
• Mount Pinatubo
– Part of a chain of volcanoes on the west coast of the
island of Luzon ins the Philippines.
– In June 1991 it erupted for 9 hours and vented 18
million metric tons of sulfur dioxide into the
atmosphere which encircled Earth in 3 weeks after
reaching the stratosphere. Largest sulfur dioxide cloud
ever detected to date.
– Sulfate aerosols formed in the stratosphere increased
reflection of solar radiation and within 3 years caused
an overall 2 F cooling of the earth.
Seasons, Solar Intensity and Latitude
• Factors that affect amount of solar energy at
earths surface
– Earth’s Rotation (once every 24 hours)
– Earth’s Revolutions around the sun (once every
365ish days)
– Tilt of Earth’s Axis (23.5 degrees)
– Atmospheric conditions
Seasons, Solar Intensity and Latitude
• Summer in the Northern Hemisphere occurs
when the Northern Hemisphere is tilted
toward the sun.
• Winter in the Northern Hemisphere is actually
when the Earth is Closest to the sun
• Seasons are NOT caused by distance of the
earth to the sun
Soil
• Composed of
– Minerals of different sizes
– Organic Materials from remaining dead organisms
– Open space that can be filled with air or water
• Good Soil should have about 45% minerals (sand,
silt and Clay) 5% organic matter, 25% air and 25%
water
Soil Development
• 1. Parent Material – this refers to the rocks and
minerals from which the soil derives. The nature
of the parent rock, which can be native to the
area or transferred in by wind, water or glacier
has a direct effect on the ultimate soil profile
• 2. Climate. This is measured by precipitation and
temperature. It results in partial weathering of
the parent material which forms the substrate for
soil.
Soil Development
• 3. Living Organisms: These include the
nitrogen-fixing bacteria Rhizobium, fungi,
insects, worms, snails, etc. that help to
decompose litter and recycle nutrients.
• 4. Topography: This refers the physical
characteristics of the location where the soil is
formed. Topographic factors that affect a soil’s
profile include, drainage, slope direction,
elevation and wind exposure.
Soil
• With sufficient time, a mature soil profile
reaches a state of equilibrium. Feedback
mechanisms involving both abiotic and biotic
factors work to preserve the mature soil
profile. The relative abundance of sand , silt
and clay is called the soil texture.
Soil Triangle
Soil Profile
Organic Vs. Inorganic Fertilizer
• Organic
– 3 common forms:
animal manure,
green manure,
compost
– Improves soil
texture, adds
organic nitrogen,
stimulates
beneficial
bacteria and fungi
– Helps to prevent
erosion
• Inorganic
• Does not add Humus to the soil
resulting in less ability to hold
water and support living
organisms
• Lowers oxygen content of the soil
thereby keeping fertilizer from
being taken up efficiently
• Supplies only a limited number of
nutrients usually only Nitrogen
and Phosphorus
• Requires large amounts of energy
to produce, transport and apply
• Releases nitrous Oxide N2O- a
greenhouse gas
Soil Erosion
• Movement of weathered rock/soil from one place to
another.
• Caused by flowing water, wind, human activity
• Soil Erosion destroys the soil profile, decreases the
water-holding capacity and compacts the soil.
• Because water cant percolate through the soil it runs
off the land, taking more soil with it (positive feedback
loop)
• Leads to damage in agricultures, waterways (canals),
infrastructure (dams). Interferes with wetland
ecosystems, reproductive cycles (as in salmon), oxygen
capacity and pH.
Agriculture techniques that lead to soil
erosion
•
•
•
•
•
Monoculture
Row cropping
Over grazing
Improper plowing of soil
Removing crop wastes instead of re-plowing
them into the ground
Types Of Soil Erosion
• Sheet Erosion- soil moves off as a horizontal
layer
• Rill Erosion- fast-flowing water cuts small
channels in soil
• Gully Erosion- Extreme case of rill erosion
where over time channels increase in size and
depth.
Desertification
Salinization
Waterlogging
Definition
Productive potential
of arid or semiarid
land falls by at least
10% due to human
activity and/or
climate change
Water that is nor
absorbed into the soil
and evaporates
leaves behind
dissolved salts in
topsoil.
Saturation of soil
with water resulting
in a rise in the water
table
Symptoms
Loss of native
vegetation; increases
wind erosion;
salinization; drop in
water table; reduced
surface water supply
Stunted crop growth;
lower yield; eventual
destruction of plants
Saline water envelops
deep roots killing
plants; lowers
productivity;
eventual destruction
of plant life
Remediation
Reduce overgrazing,
deforestation,
destructive forms of
planting, irrigation
and mining. Plant
trees and grasses to
hold soil
Take land out of
production for 2-5
years. Install drainage
pipes. Plant salt
loving plants (barley,
cotton) flush with
fresh water.
Switch to less waterdemanding plants.
Utilize conservationtillage farming, plant
plants with deep
roots, take land out
of production, install
pumping stations
Soil Erosion Case Study
• Dust Bowl
– 1930s in Oklahoma, Texas and Kansas
– Caused by plowing the prairies and resulted in loss
of natural grasses that rooted the soil.
– Drought and winds that occurred, blew most of
the topsoil away
– Caused people to leave the area
Soil Laws
• 1935 Soil Erosion Act: Established the Soil
Conservation Service. Mandates the protection of the
nation’s soil reserves. Deals with soil erosion problems,
carries out soil surveys and does research on soil
salinity. Provides computer databases for scientific
research.
• 1977 Soil and Water Conservation Act: Provides for a
continuing appraisal of US soil water and related
resources, including fish and wildlife habitats and a soil
and water conservation program to assist landowners
and land users in furthering soil and water
conservation