BWater seeps into cracks, freezes and expands by about 9%, pushing the rock apart from the inside
CFreezing temperatures make rocks brittle so they shatter on their own
DFrozen water slides rocks downhill where they break
Water expands about 9% when it freezes. When water fills a crack in a rock and then freezes, the expanding ice pushes outward with enormous force — enough to split solid rock. Repeated freeze-thaw cycles gradually widen cracks until pieces break off.
Question 2 Short Answer
After mechanical weathering breaks a piece of granite into smaller fragments, what are those fragments made of?
Think about your answer, then reveal below.
Model answer: The same minerals as the original granite — quartz, feldspar, and mica. Mechanical weathering only breaks rock into smaller pieces without changing the chemical composition. The fragments are just smaller versions of the same material.
This is the key difference between mechanical and chemical weathering. Mechanical weathering is purely physical — no chemical reactions occur. A grain of quartz that breaks off a granite boulder is still quartz. Chemical weathering, by contrast, transforms minerals into new substances.
Question 3 True / False
Weathering and erosion are the same process.
TTrue
FFalse
Answer: False
Weathering is the breaking down of rock into smaller pieces (either mechanically or chemically). Erosion is the transport of those pieces to a new location by wind, water, ice, or gravity. A boulder cracked by frost wedging has been weathered. When rain washes the fragments downhill, that is erosion. The two processes work together but are distinct.