Weathering - Erosion - Depostion VOCABULARY

Weathering

the breakdown of rocks at or near the Earth's surface

Types of Weathering

Physical & Chemical

Physical weathering is the

breaking down of rocks into smaller pieces (sediments)

Chemical weathering

changes the chemical composition of the rock

Frost action (physical weathering)

water seeps in cracks, freeze & expands

Abrasion occurs when

rocks rub and become smaller and rounder in a STREAM or WIND

Moist and warm climates favor

physical weathering

Moist and cold climates favor

chemical weathering

Root action (physical weathering)

roots grow into & under rocks, as they grow they pry the rock apart

Exfoliation

surface rock "peels off” (due to rock expanding & contracting from TEMPERATURE & PRESSURE changes

As particle size decreases

surface area increases and the rate of weathering increases

Resistant layers of rock

stick out and form cliffs or escarpments

Soils develop as a result of

weathering and biological activity

Erosion is the

movement of sediment

5 Agents of Erosion

water, glaciers, wind, wave action and mass movements

Primary force that drives the agents of erosion

gravity

Primary agent of erosion

water

Stream valleys are

V-shaped

Stream velocity depends on

gradient (steepness/slope) & volume (amount) of water

Outside of meander bend is

fast & erodes (elbow)

Inside of a meander bend is

slow and deposits (dent)

The size of the particles that can be transported

increases as stream velocity increases (direct relationship)

Evidence of gravity erosion

unsorted & angular (sharp) rocks at the base of the cliff

Longshore drift moves

sand along the beach in the direction of the ocean current

Glacial landscapes show

• U-Shaped Valleys

• Erratics

• Kettle Lakes

• Moraines

• Drumlins

• Striations

Erratics

large boulders

Striations

scratched bedrock

Outwash plains form as

a glacier melts and rivers carry small sediments (sorted) away from the glacier

Glaciers advance from the

NORTH, they formed L.I., left sand and gravel (moraines)

Wind erosion creates

sand dunes, the windward side of a sand dune has a gentle slope

Deposition

dropping or stopping of sediments after erosion

Water and wind deposits are

sorted by size and layered

Gravity and glacial deposits

unsorted and not layered

When a river enters the ocean

it slows down, deposits & called a delta (horizontal sorting)

The particles that settle out first are

larger, most dense and roundest

Watershed is a

geographic area where all the rainwater flows into a river

Physical weathering creates more

surface area

Chemical weathering occurs on

surface of rock materials

Key to chemical changes

water

What is iron oxide?

rust

Oxidation

when iron combines with oxygen to make iron oxide

Carbonation

carbonic acid causes minerals to dissolve away

Hydration

water weakens the rock & it crumbles

Weaker less resistant rocks weather

faster away then harder, more resistant

In what type of climate would the rate of chemical weathering be the greatest?

Warm & moist

In which climate does physical weathering by frost action most easily occur?

Moist and cold

Chemical weathering will occur most rapidly when rocks are exposed to the

Hydrosphere & atmosphere

Why will a rock weather more rapidly if it is broken into smaller particles?

there is more surface area exposed

Residual Soil

• soil formed & stayed in the same place (RARE)

• soil is the same substance as the underlying bedrock

Transported

moved

Transported soil

soil is made up of completely DIFFERENT material as the underlying bedrock

Particles of soil often differ greatly from the underlying bedrock in color, mineral composition & organic content. Which conclusion about these soil particles is best made from this evidence?

They are transported sediments.

Which factors most directly control the development of soils?

bedrock composition & climate characteristics

Top layer of soil has

greatest amount of material formed by biological material

Soil that contains large quantities of calcium was most likely formed by the weathering of

limestone

The composition of sediments on Earth's surface usually is different from the composition of the underlying bedrock. This observation suggests that most

sediments have been transported

On Earth's surface, transported materials are more common than residual materials. This condition is mainly the result of

erosion

Most of the surface materials in NY State can be classified as

transported soils

Granite pebbles are found on the surface in a certain area where only sandstone bedrock is exposed. Which is the most likely explanation for the presence of these pebbles?

The granite pebbles were transported to the area from a different region.

By which process’ are rocks broken up and moved to different locations?

weathering and erosion

Most rock materials are

moved by some agent of erosion at some time in their history

Velocity of a stream is influenced by (2 TERMS)

gradient & volume

Sediments are weathered by

abrasion

Gravity causes water to flow

downhill

Slope

the steeper the slope the faster the water flows

Volume

the greater the volume the faster the water flows

Oxbow lake

cut-off meander

Deposition within a meandering stream usually occurs on the inside of the curves because the

water velocity decreases

Deepest point on a graph is the

outside of the meander

After mass movement rocks look

rough and angular

Which process describes the downward sliding of the rock material?

mass movement

A landslide is an example of

mass movement