E
ARTH’S SURFACE IS
CONSTANTLY CHANGING.
ROCK IS DISINTEGRATED
and decomposed, moved to lower
elevations by gravity, and carried
away by water, wind, or ice. In this
manner Earth’ s physical landscape
is sculpted. This chapter focuses on
the first step of this never-ending
process—weathering.
Mechanical and chemical weathering
contributed greatly to the formation of the
arches and other rock formations in Utah’s
Arches National Park. (Photo by Dennis Tasa)
F O C U S O N C O N C E P T S
To assist you in learning
the important concepts in this
chapter, focus on the following
questions:
What are Earth’s external
processes, and what roles do
they play in the rock cycle?
What are the two main
categories of weathering? In
what ways are they different?
What factors determine the rate
at which rock weathers?
What is soil? What are the
factors that control soil
formation?
What factors influence natural
rates of soil erosion? What
impact have humans had?
How is weathering related to the
formation of ore deposits?