Download Weathering - Kawameeh Middle School

Weathering, Erosion, and
Deposition
• How are weathering and soil formation
related?
• How do weathering, erosion, and
deposition change Earth’s surface?
• How are erosion and deposition
related?
Weathering, Erosion, and
Deposition
• weathering
• soil
• erosion
• sediment
• physical weathering
• deposition
• chemical weathering
Weathering
• Weathering refers to the processes that
break down rocks, changing Earth’s
surface over time.
• Erosion is the moving of weathered
material, or sediment, from one location
to another.
Weathering
(cont.)
Slowly but surely, weathering and erosion
wear down mountains.
Photo by Tim McCabe, USDA Natural Resources Conservation Service
Dr. Parvinder Sethi
Weathering
(cont.)
• The process of breaking rock into small
pieces without changing the composition
of the rock is physical weathering.
• Frost wedging is what occurs when
water in rocks freezes and melts
repeatedly, breaking the rocks apart.
Weathering
(cont.)
The roots of plants
can grow into cracks
in rock and
eventually break the
rock.
Weathering
(cont.)
• The process of changing the composition
of rock and minerals by exposure to
water and the atmosphere is called
chemical weathering.
• Gases in the atmosphere can cause
chemical weathering.
Weathering
(cont.)
• Physical weathering exposes more
surface area of rocks, allowing more
water and atmospheric gases to enter
rocks.
• Chemical weathering weakens rocks by
changing the composition of some
minerals and dissolving others.
Weathering
(cont.)
• Soil consists of weathered rock, mineral
material, water, air, and organic matter
from the remains of organisms.
• Soil forms directly on top of the rock
layers from which it is made and is the
result of hundreds to thousands of years
of weathering.
Soil formation begins when physical and
chemical weathering break down rocks.
Soil formation begins when physical and
chemical weathering break down rocks.
Weathering
(cont.)
• Warm, wet climates produce soil fastest.
• Large amounts of rain can speed
weathering of rocks, and chemical
reactions are faster in warmer
temperatures.
Erosion
• The minerals and small pieces of rock
produced by weathering are called
sediment.
• Moving water causes erosion by picking
up rock pieces and sediment, which
scrape along the ground picking up more
material.
• Large masses of ice, called glaciers,
cause erosion by flowing down a
mountain and removing rock and
sediment.
• Erosion by
glaciers makes
deep valleys
and steep
peaks.
• Strong winds also can erode and move
sediment.
• Soil and rock that are not protected by
plants can be eroded by wind.
U.S. Department of Agriculture
Deposition
• Deposition is the process of laying
down eroded material in a new location.
• If the speed of flowing water decreases,
the water can no longer carry sediment
and the sediment settles at the bottom of
the water.
• Floodplains form when sediment settles
out of rivers that flood the areas next to
them.
• When glaciers melt, the water produced
by the melting ice does not flow fast
enough to carry sediment.
• Glacial deposits of sediment are called
moraines.
• Wind also can deposit sediment.
• Sand dunes are landforms made as wind
continually moves and deposits sand
grains.
Tim McCabe/NRCS
Deposition (cont.)
• The locations where sediment
accumulates are called sedimentary
basins.
• Sediment continues to be deposited in
low areas and then forced upward as
tectonic activity forms mountains.
• Physical and chemical weathering
work together and change Earth’s
surface. They break down rock and
form sediment.
• Erosion occurs when sediment is
removed and transported from where
it formed.
• Deposition occurs when sediment is
laid down in new locations.
Which process breaks rock into
small pieces without changing
the composition of the rock?
A. deposition
B. erosion
C. chemical weathering
D. physical weathering
Which are the minerals and small
pieces of rock produced by
weathering?
A. glaciers
B. sand dunes
C. sediment
D. soil
Which location accumulates
sediment?
A. soil
B. glacier
C. sand dune
D. sedimentary basin
Do you agree or disagree?
5. Rocks cannot change.
6. Sediment can be transported by water,
wind, and ice.