Fact 1: Chemical weathering causes iron in rock to oxidize.

Fact 2: Iron oxide gives a rusty red color to sedimentary rocks.

Given the two facts above, answer the question "What gives a rusty red color to sedimentary rocks?" with the following options: 
- food coloring
 - The area was once underwater
 - chemical weathering
 - remains of prehistoric life
 - deoxyribonucleic acid
 - sea urchins
 - dirt
 - earthquakes


 

   chemical weathering      