Weathering and Erosion — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
Deposition is when rocks are broken into smaller pieces by rain and wind.
Corrected: Deposition is when sediment carried by water, wind, or ice is dropped in a new place.
The corrected sentence is: "Deposition is when sediment carried by water, wind, or ice is dropped in a new place.". The original sentence "Deposition is when rocks are broken into smaller pieces by rain and wind." contained an error that needed to be fixed.
2. Fix the sentence:
Glaciers cause erosion only by melting and creating rivers of water.
Corrected: Glaciers cause erosion by slowly grinding over rock and soil as they move, carving valleys and carrying debris.
The corrected sentence is: "Glaciers cause erosion by slowly grinding over rock and soil as they move, carving valleys and carrying debris.". The original sentence "Glaciers cause erosion only by melting and creating rivers of water." contained an error that needed to be fixed.
3. Fix the sentence:
Rust on a metal fence is an example of physical weathering because the metal breaks apart.
Corrected: Rust on a metal fence is an example of chemical weathering because a chemical reaction changes the metal into a new substance.
The corrected sentence is: "Rust on a metal fence is an example of chemical weathering because a chemical reaction changes the metal into a new substance.". The original sentence "Rust on a metal fence is an example of physical weathering because the metal breaks apart." contained an error that needed to be fixed.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. A glacier is a slow-moving river of ice that carves valleys.
Glaciers are massive bodies of moving ice that erode rock as they advance, carving characteristic U-shaped valleys.
2. Sand dunes form when wind causes deposition of sand in one area.
When wind loses energy, it drops sand particles. Over time, repeated deposition builds up sand dunes.
3. Acid rain dissolves minerals in rock through chemical weathering.
Chemical weathering changes the mineral composition of rock. Acid rain (weak carbonic/sulfuric acid) dissolves carbonate minerals in limestone.
4. A delta forms where a river deposits sediment as it enters the ocean.
When a river slows as it meets the ocean, it deposits its sediment load, building up a fan-shaped delta over time.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Describe one example of chemical weathering you might see outdoors.
Sample answer: Acid rain slowly dissolves limestone statues and buildings. Over many years the surface becomes rough and details wear away because the acid changes the rock minerals.
Other valid examples: rust forming on iron, cave formation from dissolved limestone, bronze turning green (patina).
2. Why do mountains become shorter and rounder over millions of years?
Sample answer: Weathering breaks apart the rock at the top and sides. Erosion by water, wind, and ice carries the broken pieces downhill. Over time the sharp peaks are worn into lower, rounded shapes.
Uplift creates mountains; weathering and erosion continuously wear them down. Very old mountain ranges (e.g., Appalachians) are lower and rounder than young ones (e.g., Rockies).