Environmental Science NotesWeathering/Erosion/Changes in the Earth Systems

New Voc. Words: mechanical and chemical weathering, frost wedging, exfoliation, hydrolysis, oxidation, acid precipitation, erosion, deposition, mass movement erosion, creep, mudflows, landslides, rockslides, slump, avalanches, rock falls, alluvial fan, delta, Divergent, convergent, and transform plate boundaries, soil, soil profile, O-Horizon, A-Horizon, leaching, Ice Age, Interglacial periods , El Niño, tributaries, trunk, divide, watershed, stream loads, suspension, bed load, young stream, stream channel, stream bank, mature stream, meander, old stream, floodplain, Zone of aeration, cave, sinkholes, Karst topography, spring, geyser, Travertine, stalactites, stalagmites, nutrient, territory, dormant, hibernation, species, habitat, geographical range, population, community, ecosystem, biodiversity, transpiration, Carbon sequestration, biomass, and prescribed burning

Earth changes occur over time due to weathering and erosion. They affect all the Earth Systems including the Biosphere.

Weathering-Is the breaking down of rock material by mechanical or chemical means. Mechanical Examples:

o A tree root forcing the breakage of concrete in a cement sidewalk.o Swift movements of a river lifting rocks from the bottom and forcing the rocks to

collide with other rocks.o Frost wedging : The repeating thawing and freezing of water trapped in cracks of

rocks and later freezing, expanding, and breaking rocks apart.o Exfoliation : The process of the outer layers of rock being stripped away.

What is mechanical weathering and what factors are involved? Mechanical weathering exposes more surface area than chemical weathering and breaks apart a rock without changing the rock mineral composition.Factors are temperature and pressure

Chemical Examples: o Water is the main cause of chemical weathering because it dissolves minerals.

and then carries them away, leaving behind now a different composition.o Hydrolysis -the reactions of water decomposing another substance.o Water and air comes in contact with some minerals in rocks like feldspar to form

clay.o Water and Oxygen causes oxidation (a chemical reaction occurring from the

adding of oxygen and usually water) to occur when an exposed metal such as iron forms rust.

o Carbonic acid forms by mixing water with carbon dioxide from in the atmosphere. This acid dissolved minerals like calcite, the main mineral in the

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rock limestone. Over time this acid can dissolve enough limestone to form underground caves.

o Acid precipitation (usually in the form of acid rain): oxidation of sulfur dioxide to sulfuric acid or nitrogen oxide to nitric acid. Both change the pH of rain water from 7 to an average pH of 4.3 forming acid rain.

Pure water has a pH of 7.0 (neutral). The normal rain pH is 5.0-5.6 due to the natural atmospheric chemical reactions

The formation of acid rain begins with the Sun's rays reacting to oxygen. Then the oxygen reacts with water and sulfur dioxide or nitrogen oxide.

Acid precipitation can be dry (smoke and dust that stick to the ground, buildings, homes, cars, and trees) or wet (rain, fog, and snow)

Acid rain caused problems: acceleration of the rusting oxidation reaction of metals damaging plant life including trees and forests lowering the pH of the soil and water Killing of fish and other organisms that can't adapt to the lowered

pH levels hastens the natural weathering process of limestone, marble, and

mortar the decay of paint on vehicles and buildings human health problems worsen (especially those with asthma)

What is chemical weathering and what factors are involved? Chemical Weathering occurs when water, air, and other substances react with minerals in a rock and changes the mineral's composition. Factors are water plus some other substance

What are other factors that affect weathering? The greater the surface area the more weathering that occurs. Sloping of topography and decaying of organic material are also factors.

Erosion-Is the wearing away of the Earth either by surface or ground water, wind, glaciers, and/or gravity

Deposition is the final stage of erosion where the worn material is deposited somewhere else.

What are the types of erosion?1. Mass Movements -Occur when gravity alone causes loose sediments and weathered

rocks to move down a slope. Some are gradual while others are very quick.

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Climate has a great effect on the vegetation and the weathering that occurs in a particular area.

Climatic conditions determine which materials and how much of each will be available for mass movement.

Variables: The material's weight The material's resistance to slide or flow down a slope A trigger is needed to shake materials loose and cause it to go down a

slope Water : too little water may prevent sediments from holding together

allowing movement and too much water makes a slope unstable allowing movement

Types of Mass Movement: a) Creep : Slowly inches down a hill (Ex. Leaning poles)b) Mudflows : Sudden wall of mud made of mixed water and dry sediments that come

of a slope and that gets thick and pasty. (Speeds up to 100 miles/hour)c) Landslides : A rapid, downslope movement of material that occur when a thin block

of loose soil, rock, and debris separates from the underlying bedrock.d) Rockslides : Occurs when large blocks of rocks break loose from a steep slope (usually

after earthquakes and heavy rains).e) Slump : Occurs when loose material or rock layers slip down a slope.

Strong rock or sediment lies over weaker material causing the weaker to loosen and fall

Sometimes water penetrates the upper slopes and can't escape causing mudslides

f) Avalanches : Landslides in mountainous areas with a large accumulation of snow. Three types-dry (powder is the most destructive), wet, and slab

g) Rock Falls : A rock or two falling down a slope. Common at high elevations, in steep rock cuts, and on rocky shorelines.

2. Surface and Groundwater Erosion/Deposition-several typesa.) Alluvial fan: Fan shaped sediment pile on land (Surface water deposition)

b.) Delta: Triangular shaped sediment deposited into the mouth of an ocean, gulf, or lake 3. Glacial Erosion 4. Wind Erosion

I. The Changing Lithosphere The lithosphere is the Crust and part of the Upper Mantle

o The crust is either oceanic and/or continental The lithosphere is made up of several movable tectonic plates that help change the

Earth.o The movement of the plates is determined by the type of Plate Boundary

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Divergent -the plates move away from one another (often made from continental crust)

Rift valleys form which can later be filled with sea or ocean water Convergent -the plates move toward and collide into one another

Three typeso Continental to Continentalo Continental to Oceanico Oceanic to Oceanic

Transform fault -the plates slide past one another in opposite directions or at different rates or combination of both

The soil is part of the crust and changes because of natural and human disturbances.

What is soil? A mixture of weathering rock and organic matter. Soil is about 50% rock and mineral fragments and 50% air, water, and organic matter. What is a soil profile? The different layers of soil. Important for farmers and gardeners to have a good top soil layer (A horizon)

What is the types of layers of soil (Horizons) in order? There are five major horizons and then the R- horizon (non-soil layer which is the bedrock also called Regolith).

1. O Horizon -Organic layer (surface layer if present)-Composed of fresh or partially decomposed organic material that has not been mixed into the A horizon.

Absent in cultivated soils More nutrient rich than the other layers

2. A Horizon - the 1st mineral layer (top soil) has a high content of organic matter. 3. E-Horizon -is the clay, inorganic minerals, and soluble matter layer

Contains the Zone of maximum leaching -where the process of minerals being dissolved in water and carried down into the B-horizon.

4. B-Horizon -Below the E-horizon and contains the leaching material from the E-Horizon. (Color varies due to the minerals leached-very pale brown to reddish and yellowish color)

5. C-Horizon - contains active weathering, but it has little effect on the soil formation.

II. Changes in the Hydrosphere Ice age

o Glacial periods-increase in glacierso Interglacial periods -melting of the glaciers (occurring now)

El Niño o Warming of the Pacific Ocean which causes opposite conditions in some areas.

Some drought areas get flooding Some areas that normally get a lot of rain have drought conditions

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Our worst snowstorms in our area often occur during these times

Water movemento Erosiono Water Cycleo Surface Water movement

Development of Stream Systems : Most streams flow downslope and later into lakes, oceans, and

tributaries (they flow into other streams increasing in size as they are joining and adding water to it)

Small streams are called Brooks and Creeks Large streams are rivers and all its tributaries Drainage basin/Watershed: The trunk is an area of land where a

stream gets its water. The trunk separates one watershed from another by high

ground called a divide (These are the branches) Stream loads are all the materials that the water in the stream

carries consisting of living and nonliving components. Materials carried are in a solution. Suspension : All particles small enough to be held up by the

turbulence of a stream's movement. ( sand, silt, and clay) Bed Load : Consist of sand, pebbles, and cobbles that the

stream's water can roll or push along the bed of a stream. Erosion causes the divide to make the bottom deeper than the

sides and more narrow. The steep sides are called the stream bank.

The largest drainage basin is the Mississippi River Drainage Basin.

Stages of Stream Development 1. Young Stream: (Headwaters)-fastest water

Found in mountainous or hilly regions May have whitewater rapids and waterfalls

2. Mature Stream: vary in speed The curves in the stream are called the meander.

3. Old Stream: slowest water As erosion continues the stream gets very wide. The broad, flat valley floor carved with the curves is known as

the floodplain. Many farmers love to plant crops in their rich fertile areas.

o Groundwater movement The first and shallow underground water is called the Zone of aeration. This

area allows plants to get moisture. A spring forms in places where the water table meets the Earth's surface.

(They are usually cold water.)

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If springs are heated to very high temperatures, the water expands underground and forces some of it to shoot out of the ground to release the pressure. They are known as geysers. (Old Faithful in Yellowstone National Park in Wyoming shoots out about 40,000 L of water and steam once each hour.)

Groundwater will keep going lower in elevation until it reaches a layer of impermeable rock below the aquifer. This rock acts like a barrier and the water can't move down any deeper.

As groundwater and carbon dioxide mix they form carbonic acid and cause erosion in cracks enlarging in the limestone forming caves.

There are three main types of caves:1. Carbonic Acid Solution Caves - Have water pass through the air and

ground to pick up Carbon dioxide to form Carbonic Acid. Slow process. Example: Mammoth Cave in Kentucky is the longest cave system in the world.

2. Lava Tube Caves -Old Lava tubes that formed as the red-hot lava flows down the side of the volcano are now empty and hollow. Example: Hawaii Volcanoes National Park

3. Sulfuric Acid Caves -Hydrogen sulfide gas rose from petroleum deposits deep in the ground to mix with water creating Sulfuric acid. This substance dissolves rock much faster than Carbonic Acid leaving huge rooms in caves. Example: Carlsbad Caverns in New Mexico

Groundwater deposits are made from natural deposits of dissolved limestone in water with calcium ions that often drip (known as pearls) slowly from the cracks in the cave walls and ceilings. They leave deposits of calcite.

Travertine is the inorganic limestone that drips from caves Stalactites : Hang from the roof Stalagmites : form on the floor

Sinkholes are a depression formed when the roof of a cave collapses. Limestone regions with caves and sinkholes are called Karst

topography. Most prominent regions in the USA to have caves and sinkholes is

Mammoth Cave in Kentucky. Most of the lakes in Central Florida are made of sinkholes.

III. Changes in the Atmosphere Greenhouse effect

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Diagram from Project Learning Tree-Southeastern Forests and Climate Change

o Ozone depletion

o Interglacial climate-when glaciers are not forming

IV. Changes in the BiosphereOrganism must have food for energy in the form of nutrients to stay healthy. They must also find water and shelter. Competition for these items is an ongoing battle.

Living Spaceo Territory -living space claimed by an individual animal or group of animals

Climateo Dormant -The life processes slow downo Hibernation -A dormant sleep-like condition

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Habitat : Where an organism lives Geographical Range : The total area where a species lives Population : Group of the same species living in the same geographic area Community : All the different organism living in the same geographic range Ecosystem : Biotic and Abiotic factors interacting together in their community

Organization (or Hierarchy) of Life1st Organism (species)-lowest2nd Population3rd Community4th Ecosystem5th Biosphere –top

Biosphere ______________

Ecosystem________________________

Community ____________________________________

Population ________________________________________________

Organism

You Depend on Forests For Many Things in the Environment

How does the forests benefit us?1. Everyday needs: clean water, oxygen, nutrient cycling, carbon storage, temperature

regulation and rainfall-transpiration (the absorption and releasing of water through the roots and leaves of trees). The movement of water can influence area temperatures and yearly rainfall.

2. Carbon sequestration- the process through which CO2 from the atmosphere is absorbed by plants, crops, and trees through photosynthesis, and then is stored as carbon in the biomass (tree trunks, branches, leaves, roots, and the soil around them).

3. Heat supply: charcoal and firewood4. Shelter: lumber5. Food/supplies/medicine: nuts, paper, medicine, turpentine, etc.

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6. Recreation: fishing, hiking, hunting, solitude, etc.7. Wildlife Habitat

How are forests today changing?1. Invasive species2. Fire-shapes many forests, allows species reproduction, influences decomposition, and

nutrient cycling3. Forest management -prescribed burning (controls natural or man-made fires to burn in a

certain area, under specific weather conditions to reduce the fuel of a dangerous fire. 4. Climate change: The amount of CO2 in the atmosphere has increased by 35% from 1850 to

2010. Climate change has occurred mainly because of human activities: deforestation and burning of fossil fuels. Greenhouse gases such as CO2 will warm the Earth's atmosphere, causing changes in rainfall, sea level, and weather patterns.

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