NCVPS Earth and Environmental Science

Lecture and Study Guide 3 Rocks, Soils, Erosion, Weathering

and DepositionPictures added to Study Guide

By Kella RandolphAll art from Creative Commons via Bing Online Images

Music from Kalinda

3 types of rocksIgneous, sedimentary, metamorphic

Igneous

intrusive igneousIntrusive- hardens underground

extrusive igneousExtrusive- hardens above ground

Metamorphic rocks

What are the forces that form metamorphic rocks?Heat and pressure

Sedimentary rocksThere are hundreds of different sedimentary rock types.

How are sedimentary rocks formed?Compaction and cementation of sediments.

What is humus made of?Decaying organic matter.

Name the layers of a soil profile.Organic layer

Topsoil

Weathered parent material

Unweathered Parent material

Why is soil important to living things?

Because plant roots need soil to grow.

What is loamy soil?A mixture of sand, clay and humus

3 basic soil particlesSand, silt and clay

sand

silt

clay

Define weathering.

The breaking down and building up of the Earth’s surface.

What are the 2 types of weathering?

Physical/Mechanical and Chemical

Mechanical or Physical weatheringName six main processes of physical weathering.

Gravity

Exfoliation

Impact and abrasion

Frost action

Temperature

Organic activity

How long does it take soil to form from parent rock?

Hundreds of years

Gravity

Impact and abrasion

Exfoliation

Frost action

Temperature

Alternating freeze and thaw creates cracks in stone, breaking it into smaller pieces.

Organic activity

Tiny roots excrete acids that eat into stone, providing a hold for the tree and nutrients as well.

Chemical weatheringName five main processes of chemical weathering.

Water

Oxidation

Carbonation

Sulfuric acid (acid rain)

Plant acids

Water weatheringAs glaciers move, they gouge out large amounts of rocks and soil, carrying these many miles.

Oxidation

As the oxygen in the air interacts with the iron in the soil, the iron oxidizes, or rusts, turning red.

Carbonation

Water dissolves minerals and redepositsthem as water drips from the ceiling of a cave.

Sulfuric acid (acid rain)

Acid rain is formed when acidic air pollutants mix with rain.

Plant acids

Acids from tiny roots dissolve rock allowing the root to grow into a stone.

What are the five causes of soil mismanagement?

Clearing vegetation

Plants planted in the wrong location

Overuse of pesticides and fertilizers

Pollution of cars and factories

Compaction from animals roads and construction

Clearing vegetation

Plants planted in the wrong location

It is a mistake to plant a tree where soil or environmental conditions will not favor good growth, where it will eventually need regular and heavy corrective pruning or where it may need to be completely removed within a few years.

Overuse of pesticides and fertilizers

Overuse of DDT resulted in thin eggshells for eagles. A food chain: worms on plants ate poison. Birds and other small animals and fish, ate the worms. Eagles ate the animals that had eaten the worms. The pesticide was carried in the bodies of every creature that ate. When female eagles laid eggs with thin shells, due to the DDT, the eggs broke when the mother sat on them to keep them warm. Baby eagles died before they could hatch, because the shells broke. The American Eagle was almost made extinct. DDT is banned in the USA and some other countries now.

Pollution of cars and factories

Compaction from animals roads and construction

Define erosion.The process by which weathered material is moved from one place to another.

Define deposition.The process by which sediments are laid down.

Name five agents of erosion.Wind

Gravity

Running water

Waves

Glaciers

Wind

Gravity

Rain soaked ground becomes mud. Mud slides downhill, carrying trees and rocks with it.

Running waterCliffs eroded by running water from rain and waves

Waves

Coastal erosion wearing away beach

GlaciersIce in glaciers grabs onto soil and rocks, dragging them along as the glacier melts back or slides forward.

Why does running water account for the greatest changes on the landscape?Because over time, it can erode rocks and cause canyons.

How does urban storm water affect the water quality?After a storm, all the city’s pollution gets washed into the creeks and streams.

down cuttingDowncutting is the downward erosion of a stream channel

stream energyStream energy is the velocity of a stream.

stream loadThe stuff that gets carried in a stream.

Stream load is the amount of stuff the water is carrying.

How does stream deposition occur?Results from decreasing water velocity.

Where do river systems come from?All the water ways that drain into a river from tributaries

Describe an oxbow lake.When a meander gets cut off from the main river, an oxbow lake forms.

Describe a delta.This is where a river empties into a larger body of water, causes a back up usually creating a wetland.

What are levees?

Natural ridges that hold back water.

What are the four factors that wind erosion is dependent upon?

(1)Size of particles being carried

(2) Speed of the wind

(3) Length of time the wind blows

(4) Resistance of rocks exposed to wind

Describe how waves constantly change shorelines.Waves receive their energy from winds that blow across the water surface. The size of a wave depends on how fast, how far, and how long the wind blows.

What are seven ways to control erosion?Construction sites can use sediment fencing.

Contour farming

Collect and direct urban run-off

Terracing

Strip cropping

Plant vegetation

Anchor the soil

Construction sites can use sediment fencing.

Contour farming

Collect and direct urban run-off

Terracing

Strip cropping

Plant vegetation

Anchor the soil

There are many things that we can do to help conserve and protect our

precious natural resources. The earth is our home. Keep it healthy!