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Weathering, Erosion, and
Deposition
Weathering Notes
EQ: How do mechanical and chemical
weathering differ?
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Weathering
• Breakdown of rock into smaller and smaller
pieces
Mechanical Weathering
• Weathering by physical means
– Ice – water expands when it freezes and causes ice
wedging
– Wind, water & gravity – by abrasion (the grinding and
wearing down of rock by other rocks). Abrasion
happens more rapidly in dry climates.
– Plants – roots grow into cracks forcing the rock to split
apart
– Animals – burrow and expose fresh rock surfaces to
be weathered
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Chemical Weathering
• Weathering by chemical means. (A new
substance is formed)
• Remember: signs of chemical change.
Please Excuse Burps, Sneezes & Coughs Precipitate, Energy change, Bubbles, Smell & Color change
• Water – Rock is dissolved by water, called
hydration
• Acids – Acids in precipitation and groundwater
slowly break down rocks, called carbonation;
can form caves in limestone
• Air- oxygen reacts with iron to form iron oxide
or rust, called oxidation . Oxidation happens
more rapidly in moist climates.
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Aquifer-an underground body of water.
• Ex: Edwards Aquifer was formed by weathering of
limestone through carbonation.
Surface Area
• The more surface area exposed, the faster a rock will
wear down. (Ex: 50lbs of pebbles will weather faster
than a 50lb boulder)
Time
• The longer a rock is weathered, the smaller and rounder
it will become
Erosion and Deposition Notes
• EQ: How do weathering, erosion, and
deposition work together to shape the Earth?
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Erosion
•The movement of sediment (rock particles)
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Agents of Erosion
• Wind, Water, Gravity and Glaciers
Wind Erosion
• Wind moves particles
• Most common in dry climates
• Trees and plants reduce wind erosion
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Water Erosion
• Most powerful agent of erosion
• Ocean waves shape rocks on a shoreline.
• Water flows downhill following gravity
Glacier
• Enormous ice formations with rock material
• Move downhill due to gravity
• slides over rock formations—breaks rocks
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Deposition
• Dropping or depositing of sediment
• Broken rock pieces settle in different places
• Form new (sedimentary) rock
• Creates beaches, shorelines and deltas
Soil Formation
• Heaviest sediment on bottom and lighter
sediment lies on top
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• W.E.D. change surface of the earth
• shape mountain
• carve valleys and canyons
• Helpful graphic
• Weathering is the breaking down of rock, so
the W is broken.
• Erosion is the movement of sediment, so the E
is on wheels.
• Deposition is the depositing or dropping of
sediment, so the D is on its side.
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