Fact 1: Mechanical weathering is when rocks are broken down by mechanical means.

Fact 2: Pysical weathering is the mechanical breakdown of rocks.

Given the two facts above, answer the question "What is when rocks are broken down?" with the following options: 
- roof weathering
 - Plant growth is reduced
 - brick weathering
 - Physical weathering
 - remains of prehistoric life
 - at or near the margins
 - home weathering
 - major threat to health


 

    Physical weathering     