Weathering and Erosion

Word	Definition
Weathering	the breaking down of rocks.
Physical weathering	breaks down of rocks into smaller rocks.
Chemical weathering	changes a rock into different substance which is usually a weaker material.
Soil	is a mixture of weathered rocks and humus.
Humus	is the decomposed remains of dead plants and animals.
Erosion	the transportation of rocks and sediments by river, wind, glacier and force of gravity.
Mass movement	the moving of sediments and rocks by gravity.
Agents of erosion	the substances that move rocks and sediments. Examples are water, wind, ice.
Glacier	a large block of ice that move by gravity.
Deposition	the settling of sediments that were carried by agents of erosion.
Sorting	the separation of sediments by their size.
Dunes	hills of sand formed as a result of the erosion and deposition of sand by wind.
Dynamic Equilibrium	the rate of deposition is equal to the rate of erosion.
Watershed	is also called water basin. Watershed is an area where smaller rivers all flow into a larger river.
Meander	is the wandering of a river.
Discharge	is the amount of water flowing in a stream.
Drainage pattern	shows the path rivers flow in an area.
Runoff	is the flow of water downhill on a surface due to gravity.
Permeability	is a measure of how easily water flows through a substance.
Porosity	is the amount of empty space in a substance.
Capillarity	water goes up in a thin, narrow tube.
Striations	the parallel scratch marks left behind by glaciers dragging loose sediments against the surface of a bedrock .
Moraines	the large amount of rocks left behind by a glacier (glacial deposition).

Word

Definition

Weathering

the breaking down of rocks.

Physical weathering

breaks down of rocks into smaller rocks.

Chemical weathering

changes a rock into different substance which is usually a weaker material.

Soil

is a mixture of weathered rocks and humus.

Humus

is the decomposed remains of dead plants and animals.

Erosion

the transportation of rocks and sediments by river, wind, glacier and force of gravity.

Mass movement

the moving of sediments and rocks by gravity.

Agents of erosion

the substances that move rocks and sediments. Examples are water, wind, ice.

Glacier

a large block of ice that move by gravity.

Deposition

the settling of sediments that were carried by agents of erosion.

Sorting

the separation of sediments by their size.

Dunes

hills of sand formed as a result of the erosion and deposition of sand by wind.

Dynamic Equilibrium

the rate of deposition is equal to the rate of erosion.

Watershed

is also called water basin. Watershed is an area where smaller rivers all flow into a larger river.

Meander

is the wandering of a river.

Discharge

is the amount of water flowing in a stream.

Drainage pattern

shows the path rivers flow in an area.

Runoff

is the flow of water downhill on a surface due to gravity.

Permeability

is a measure of how easily water flows through a substance.

Porosity

is the amount of empty space in a substance.

Capillarity

water goes up in a thin, narrow tube.

Striations

the parallel scratch marks left behind by glaciers dragging loose sediments against the surface of a bedrock .

Moraines

the large amount of rocks left behind by a glacier (glacial deposition).

Key Things to Know in Weathering and Erosion

Chemical weathering occurs mostly in warm, humid climates.
Physical weathering occurs mostly in cold, humid climates (good for frost wedging).
Permeability (connection of holes); as particle size increases, permeability increases.
Porosity does not depend on particle size. Porosity is the amount of holes in a substance.
As particle size increases, permeability increases. Permeability is the connection of holes in a substance.
Capillarity increases when particle size decreases. Capillarity is the movement of water upward.
Dynamic equilibrium means balance.
Gravity causes most erosion.
Streams are the number one agent of erosion.
Stream velocity depends on slope and discharge.
Velocity is fastest on the outside of meander bend.
Heavy, round, and dense particles settle out first in water.
Graded bedding (vertical sorting): biggest sediments are on bottom.
Glacial sediments are unsorted with scratches in a U-shaped valley.
Stream deposits are sorted, round and smooth, V shaped valley.
When a rock is broken into smaller pieces, surface area increases and weathering rate increases.
POROSITY DOES NOT DEPEND ON PARTICLE SIZE.
MARINE (SEA) FOSSILS ON MOUNTAIN TOPS INDICATE THAT THE LAND HAS BEEN UPLIFTED.

Example 1

Deposition within a meandering stream usually occurs on the inside of the curves because the
(1) water velocity decreases
(2) stream gradient increases
(3) water is deeper
(4) stream is narrower

Deposition happens when the stream of water slows down. Water slows down in the inside curve of the meandering stream. (1)