1. In a heterogeneous mixture, the substances
A. can be physically separated.
B. are chemically combined.
C. can only be separated through chemical processes.
D. break down into new substances.

weathering - colorado river carves land in arizona to form the grand canyon. cracks form in a sandstone wall surrounding a house. a marble statue near the science museum is changing color due to rainfall

erosion - after a rainstorm, soil and rock piees litter the roadways. the sand dunes in the sahara desert are changing shape.

here's your answer.