Weathering and SoilFormation

Chapter 6

WARM-UP #1

•The breaking down of rocks and other materials at Earth’s surface is

ANSWER

• weathering.

WARM-UP #2

•Freezing and thawing cause

ANSWER

• Ice wedging

VOCABULARY

•Weathering•Erosion•Uniformitarianism

weathering and erosion

• Weathering – the process that breaks down rock and other substances at the Earth’s surface.

• Erosion – forces of erosion carry the pieces away…..weathering and erosion work together to break down and carry away rocks on Earth’s surface.

vocabulary

•Uniformitarianism – principles that operate today operated in the past

WARM-UP #3

•Which is a cause of chemical weathering?

ANSWER

• Acid rain

WARM-UP #4

•Mechanical weathering is faster in a climate that is

ANSWER

• warm

VOCABULARY

•Mechanical weathering•Abrasion• Ice wedging

MECHANICAL WEATHERING

• Mechanical weathering – weathering where the rock is broken into smaller pieces….each piece is still the same composition….mechanical weathering is a slow process

EXAMPLES

• Freezing and thawing, release of pressure, plant growth, actions of animals, abrasion

• Abrasion – grinding away of rocks by rock particles carried away by wind, water, ice, or gravity

• Ice wedging – water seeps into cracks – expands when it freezes – ice is like a wedge that breaks the rock apart

WARM-UP #5

•When dead plants and animals decay, they form

ANSWER

• humus

WARM-UP #6

•A solid layer of rock under the soil is called

ANSWER

• bedrock

VOCABULARY

•Chemical weathering•Oxidation•Permeable

Chemical weathering

• Process that breaks down rock through chemical changes………..causes are the action of water, oxygen, carbon dioxide, living organisms, and acid rain.

VOCABULARY

• Oxidation – when iron combines with oxygen in the presence of water………….rust

• Permeable – rock that is full of tiny holes…allows water to seep through easily….permeable rocks will weather quickly when exposed to chemical weathering.

WARM-UP #7

•In the United States, most of the eastern states are covered with

ANSWER

• Forest soil

WARM-UP #8

•Living things that break down dead organisms are called

ANSWER

• decomposer

VOCABULARY

•Soil•Bedrock•Humus

VOCABULARY

• Soil – loose weathered material on Earth’s surface where plants can grow• Bedrock – solid layer of rock below

the soil• Humus – decayed organic material in

soil

WARM-UP #9

•Soil fertility is a measure of

ANSWER

how good soil is for growing plants.

WARM-UP #10

•Farmers leave dead plants in their fields in the soil conservation method called

ANSWER

• conservation plowing.

VOCABULARY

•Fertility•Loam•Soil horizon

VOCABULARY

• Fertility – measure of how well the soil supports plant growth• Loam – soil made up of equal parts

of sand, clay and silt• Soil horizon – is how the soil

develops into layers ………the layers differ in color and texture

WARM-UP #11

• The movement of rock pieces and other materials on Earth’s surface is called ____________________________.

ANSWER

• erosion

WARM-UP#12

• The kind of weathering that breaks rocks into smaller pieces is _____________weathering.

ANSWER

• mechanical

VOCABULARY

•Topsoil•Subsoil•Litter•Decomposers

TOPSOIL AND SUBSOIL

• Topsoil – is horizon A ….crumbly, dark brown soil that is a mixture of humus, clay and other mixtures• Subsoil – is horizon B….clay and

other particles washed down from horizon A…little humus

LITTER AND DECOMPOSERS

• Litter – is what is left of the plant before it adds to humus…..leaves, roots, and the plant itself when it dies.• Decomposers – organisms that break

down the remains of dead organisms into smaller pieces and digest them with chemicals.

WARM-UP#13

• The scraping of rock by wind-blown pieces of rock is called __________________________.

ANSWER

• abrasion

WARM-UP#14

•The material on Earth’s surface in which plants can grow is ___________________.

ANSWER

• soil

VOCABULARY

• Sod – thick masses of tough roots at the surface of the soil……..keeps the soil in place and held onto moisture.• Natural resource – anything in

the environment that humans use

WARM-UP #15

•The B horizon is also called _____________ .

ANSWER

• subsoil

WARM-UP #16

•In ______________ weathering, the makeup of rock changes.

ANSWER

• chemical

VOCABULARY

• Dust Bowl – ruined farmland on Oklahoma and parts of the surrounding states…..caused by years of droughts and lots of plowing tuned the top soil to dust and it blew away.• Soil Conservation – management of

the soil to prevent it’s destruction.

WARM-UP #17

•Different kinds of rock weather at different ___________.

• rates

WARM-UP #18

•The last layer of soil to form is the _____ horizon.

• C

PLOWING

• Contour Plowing – plow the fields along the curve of the slope….slows runoff and preserves the soil from erosion.

• Conservation Plowing – disturb the plant cover and soil as little as possible…dead weeds and stalks are left in the ground to help return soil nutrients.

CROP ROTATION

• Farmers plant different crops in the field each year………helps maintain the nutrients in the soil

WARM-UP #19

•Loss of _____________ causes soil to lose its fertility.

• topsoil

WARM-UP #20

•One way to keep soil fertile is to grow a __________________ kind of plant every year.

• different