Definition & Concepts
Which type of weathering is caused by living organisms such as plants, animals, or humans?
Biological Weathering
Water enters cracks in a rock, freezes, expands, and eventually breaks the rock apart. What is this process called?
Freeze-thaw (ice wedging)
Even though it looks clean, rainwater can break down rocks because it always contains a small amount of this gas from the atmosphere
Carbon dioxide
Which of the following is NOT an agent of biological weathering?
A. Bacteria
B. Plant roots
C. Acid rain
D. Earthworms
C. Acid Rain
A farmer in the tropics notices that granite in his field has turned into soft clay over many years. Which type of chemical weathering is at work?
Hydrolysis
Which type of weathering involves chemical reactions that change the composition of rocks?
Chemical Weathering
Rocks at the beach become smooth and rounded after years of waves moving them back and forth. Which type of mechanical weathering is this?
Abrasion
What role does water play in chemical weathering?
A. It carries rocks from place to place
B. It freezes and expands inside cracks
C. It acts as a solvent, breaking down minerals
D. It pushes rocks against each other
C. It acts as a solvent, breaking down minerals
Which of the following best represents biological weathering?
a. Carbonic acid dissolving rock
b. Wind breaking rock particles
c. Tree roots breaking through a sidewalk
d. Water freezing in rock cracks
c. Tree roots breaking through a sidewalk
TRUE OR FALSE
Oxidation is considered a type of biological weathering because it often happens in the presence of plants.
False.
Oxidation is a chemical weathering process, even if it sometimes occurs near biological activity.
Mechanical (physical) weathering
In deserts, large rock surfaces peel off in sheets like an onion due to extreme temperature changes between day and night. Which process is this?
Exfoliation
Which condition would increase the rate of chemical weathering the most?
A. Cold and dry climate
B. Hot and dry climate
C. Cold and wet climate
D. Hot and wet climate
D. Hot and wet climate
Which human activities can accelerate biological weathering by exposing or breaking rocks?
Construction, mining, and farming
After a typhoon, a mountain slope collapses and soil rushes down, burying part of a village. Which geologic process is this?
mass wasting (landslide or mudflow)
What is the difference between erosion and deposition?
Erotion is the MOVEMENT of weathered material, while Deposition is when those materials are DROPPED OFF in a new location.
TRUE OR FALSE
Physical Weathering only occurs because of water
False
This type of chemical weathering creates sinkholes by dissolving limestone with weak carbonic acid from groundwater.
Carbonation
Earthworms and ants don't directly break rocks, but they speed up weathering in this hidden way. Explain how.
By burrowing and loosening soil, they expose rocks to air and water which increases both mechanical and chemical weathering.
Tree roots push through the cracks of a concrete sidewalk, breaking it apart. Which type of weathering is this?
Biological Weathering
Name the four main external geologic processes that shape the Earth's surface.
A rock breaks into smaller pieces after years of water freezing and melting inside its cracks. The rock is still made of the same minerals. Is this mechanical or chemical weathering, and why?
Mechanical Weathering. Because the rock's composition did not change, it only broke into smaller pieces.
The reddish-brown color of Uluru (Ayers Rock) is a result of this type of chemical weathering.
Oxidation
Give one PHYSICAL and one CHEMICAL way that biological weathering occurs
PHYSICAL: Plant roots crack rocks
CHEMICAL : Lichens release weak acids that dissolve minerals
The smooth, round pebbles found along the beach have been shaped by years of waves constantly crashing and grinding them against each other. Which specific type of weathering is this?
Mechanical weathering (abrasion)