1

Chapter 12 Weathering, Soil, & Erosion Guided Reading Notes

12.1) Weathering

When rock is exposed to the ______________________________ it begins to

break-up or _______________________. The movement of this broken rock

from one place to another is called _____________. Rain, ___________, and

___________ are agents of erosion. These agents will eventually deposit the

weathered rock. The deposition of the weathered rock takes place in many

locations across the earth’s surface including lakebeds, streambeds, and on

the ocean floor.

The disintegration of rock is called _______________________ weathering. The

breaking of a rock cliff into boulders and pebbles is an example of ________

weathering. The decomposition of rock is called ________________________

weathering. ______________________________ is the most important agent of

chemical weathering. The formation of clay minerals from feldspar is an example

of ______________________________ weathering. Mechanical weathering and

chemical weathering almost always act __________.

Mechanical Weathering

Common mechanical weathering processes include ______________________,

wetting and drying, abrasion by ______________________________________,

actions of _____________________ and ________________________, and the

___________________________________ that results from upward expansion.

Water freezes and expands by _____________ % breaking-up rock in a process

called ______________________. Ice wedging is the most damaging weathering

process in places that have frequent _________________ and _____________.

Road potholes are a common problem in areas that have these conditions.

The repeated ______________ and ____________ of rocks containing clay can

cause the rocks to fall apart or ___________________________. Plants can use

their _______________ to break apart rock in a process called _____________.

Animals like _______________and ________________ can dig holes in the soil

allowing ___________ and __________ to reach the bedrock weathering it.

2

Plutonic rock like granite cools and crystallizes underground. When this rock

reaches the surface it begins to expand and break apart. This peeling of the rock

is called _____________________________. Stone Mountain in Georgia is a

rounded peak called an exfoliation dome.

Chemical Weathering

Chemical weathering of rock is the result of the actions of _____________,

__________, ___________________, and __________________________.

The chemical reaction of water with minerals is called _________________.

When minerals react with water _______________ is usually the substance

that results from the reaction. The chemical action of oxygen with other

substances is called __________________ This reaction produces ________

on the surface of the substances that have reacted with oxygen. Iron-bearing

minerals like _________________ and ____________ are most easily

attacked by oxygen. When water absorbs _____________________ from the

atmosphere it becomes ______________ acid. The acid will easily weather

rocks that contain the mineral ________. Caves and caverns are the result of

carbonic acid weathering ____________. Unique plants called lichens(moss)

produce a very weak plant acid that can chemically weather rock.

Rates of Weathering

The mineral _______________ (7 on Moh’s Hardness Scale) tends to resist

mechanical and chemical weathering. _______________, ______________,

_____________, _____________, _____________, and _______________

are broken into smaller pieces by mechanical weathering and then attacked

by chemical weathering. Most are turned into _______________. Some like

_______________ and _______________ are carried off in ____________.

_______________ and _______________ weather more rapidly in _______

climates than in dry climates. Sedimentary rocks like sandstone and

conglomerate are only as durable as the _______________ that holds them

together. Rocks held together by _______________ tend to weather more

rapidly than rocks that contain silica cement. The weakest of the

sedimentary rock is _______________. _______________ and __________

3

are fairly resistant to mechanical weathering. However, the _____________

that makes up these rocks is under attack by the acid in water. The rate of

weathering is determined by a number of factors. The first is ____________ type.

Sedimentary rock like shale will weather _______________________.

While igneous rock like granite and metamorphic rock like gneiss are very

_______________ to the agents of weathering. A rock’s ________________

also determines its rate of weathering. The greater the exposed surface area,

the faster the weathering. Climate will also determine rates and types of

weathering. Warm, wet climates favor ___________________ weathering.

Cold, dry climates favor ______________________ weathering. Weathering

is a very _______________ process.

12. 2) Soil

How Soil Forms

Weathered rock and a little ______________ matter have created a priceless

resource we call _______________. Soil is made up of _______________,

clay, and _____________________. These sediments develop from the soils

________________________________ or rock from which the soil formed.

Soil that is sitting on top of its parent material is called ________________.

Soil that is no longer with its parent material is called _________________.

4

Mature Soil Profile

The diagram above is of a ______________________________ soil profile.

Soil layers A, B, and C are called _____________________. Layer A in the

diagram is called the ______________. This layer is generally gray to black

in color depending upon the amount of ___________ or living(once living)

material contained in the soil. Layer B in the diagram is called the _______.

This layer is usually red to brown from the iron oxides that leach from the

topsoil. Layer C is slightly weathered bedrock.

Soil Composition

Areas that have constant high temperatures and heavy rainfall develop

laterite or _____________________ soils. Areas that receive enough rainfall

for tall grass to grow but not trees develop ______________________ soils.

Humid regions that have cool seasons and forests of hardwood and

evergreen trees develop ___________________ soils. Very dry climates

develop _____________________ soils. Areas high in elevation and latitude

develop _____________________ soils.

5

Label the following Soil Map of North America

Label the map with the following soil types: Arctic Soil, Forest Soil, Grassland

Soil, Desert Soil, Tropical Soil, Mixed Soils (Mts. / Valleys)

12.3 Mass Movements and Erosion

The movements of loose earth materials like soil and rock down slope are called

______________________. Mass movements are caused by _______________

an agent of erosion. The removal and transport of materials by natural agents

such as gravity, wind, and running water is called ________________________.

Mass movements include _______________ the slow, imperceptible down slope

movement of soil. Creep can only be noticed by its _______________________.

Creep causes _________ __________, ___________, and other objects fixed in

the soil to lean ____________________. ________________ in the soil probably

adds to ___________________. Mass movement will result in ______________

or piles of sediment that build-up at the base of a hill or cliff. ________________

is common wherever there are ____________________. The sudden movement

6

of a mass of bedrock or loose rock down the slope of a hill, mountain, or cliff is

called a ____________________________. Masses of snow, ice, soil, or rock, or

mixtures of these materials are referred to as an ________________________.

Small blocks of land that tilt and move downhill are called _________________.

Slumps are common along cliffs, steep hills, and _________________________

next to highways. The rapid movement of water-saturated clay and silt down

slope is called a _________________________. A less fluid form of a mudflow is

called an ________________________________. Subsidence occurs when the

ground collapses into a mine or cavern. Subsidence can also result from the over

pumping of groundwater.

What areas tend to be at greater risk for mass movements? Why? ___________

________________________________________________________________

________________________________________________________________

How can people avoid landslides and mudflows if they live in an area that is at

risk for these events? _______________________________________________

________________________________________________________________

________________________________________________________________

12.4) Soil as a Resource

Soil _______________ is the removal of topsoil a natural resource, by the

action of __________________, __________________ or _____________.

____________________ is a method of soil conservation that is used break

-up the wind that blows across level fields creating soil erosion. Another

method of soil conservation involves planting with the shape of the land.

This process involves planting across a hillside to stop soil erosion. This

method of soil conservation is called ______________________________.

Farmers use a soil conservation method called _______________________

on steep hillsides to stop erosion. Strip cropping is another soil conservation

method that involves alternating plant rows that cover the ground completely

with those that leave the soil exposed to the agents of erosion.