Earth's Surface Changes: Weathering and Erosion
Chapter 1, Section 3
I. Changes on the Earth’s Surface
A.
Weathering
i.
Is the breakdown of rock at or near the earth’s
surface into smaller and smaller pieces.
ii.
Two types of weathering.
a.
Mechanical
b.
Chemical
a. Mechanical Weathering
1.
Occurs when rock is actually broken or
weakened physically.
2.
Breaks large masses of rock into smaller
pieces, producing boulders, stones, pebbles,
sand, silt and dust.
3.
Most common type of Mechanical
Weathering is known as
Frost Wedging
.
b. Chemical Weathering
1.
Alters a rock’s chemical makeup by changing
the minerals that form the rock or combining
them with new chemical elements.
–
This means chemical weathering can change one
type of rock into an entirely different type
causing the loss of valuable minerals (
leaching
).
–
Most important factors water and carbon dioxide.
*** Acid Rain is another type of
chemical weathering. Some known
causes of acid rain are acid-
producing agents from the ocean,
volcanic activity and industrial
pollution.
c. Observing Weathering
1.
Besides the effects on old stone structures
such as tombstones, it also softens the sharp
features on carved stone statues, and breaks
down the mortar that holds together stone
or brick walls.
2.
Weathering also changes natural landforms,
jagged mountains can turn to rounded hills
over millions of years.
B. Erosion
1.
The movement of weathered materials such
as gravel, soil and sand.
2.
The three most common causes of erosion
are a. water, b. wind and c. glaciers.
a. Water
i.
Moving water – rain, rivers, streams and
oceans – (mixed with sediments AKA small
particles of soil, sand and gravel) is the
greatest cause of erosion.
b. Wind
i.
Caused the “Dust Bowl” during the 1930s.
ii.
Drought caused soil to dry, wind blew and
stripped the land of its minerals and
nutrients.
iii.
Sandstorms are major causes of erosion.
c. Glaciers
i.
Huge, slow-moving sheets of ice.
ii.
While rivers cut sharp-sided, V-shaped
valleys, glaciers carve out valleys that are
rounded and U-shaped.
Weathering is the breakdown of rock into smaller pieces due to mechanical and chemical processes. Mechanical Weathering breaks rocks physically, while Chemical Weathering alters a rock's chemical makeup. Observing Weathering effects on structures and landforms over time. Erosion involves the movement of weathered materials like gravel, soil, and sand driven by water, wind, and glaciers.
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Presentation Transcript
I. Changes on the Earths Surface A. Weathering i. Is the breakdown of rock at or near the earth s surface into smaller and smaller pieces. ii. Two types of weathering. a. Mechanical b. Chemical
a. Mechanical Weathering 1. Occurs when rock is actually broken or weakened physically. 2. Breaks large masses of rock into smaller pieces, producing boulders, stones, pebbles, sand, silt and dust. 3. Most common type of Mechanical Weathering is known as Frost Wedging.
b. Chemical Weathering 1. Alters a rock s chemical makeup by changing the minerals that form the rock or combining them with new chemical elements. This means chemical weathering can change one type of rock into an entirely different type causing the loss of valuable minerals (leaching). Most important factors water and carbon dioxide. *** Acid Rain is another type of chemical weathering. Some known causes of acid rain are acid- producing agents from the ocean, volcanic activity and industrial pollution.
c. Observing Weathering 1. Besides the effects on old stone structures such as tombstones, it also softens the sharp features on carved stone statues, and breaks down the mortar that holds together stone or brick walls. 2. Weathering also changes natural landforms, jagged mountains can turn to rounded hills over millions of years.
B. Erosion 1. The movement of weathered materials such as gravel, soil and sand. 2. The three most common causes of erosion are a. water, b. wind and c. glaciers.
a. Water i. Moving water rain, rivers, streams and oceans (mixed with sediments AKA small particles of soil, sand and gravel) is the greatest cause of erosion.
b. Wind i. ii. Drought caused soil to dry, wind blew and stripped the land of its minerals and nutrients. iii. Sandstorms are major causes of erosion. Caused the Dust Bowl during the 1930s.
c. Glaciers i. ii. While rivers cut sharp-sided, V-shaped valleys, glaciers carve out valleys that are rounded and U-shaped. Huge, slow-moving sheets of ice.
