Mountains on the flanks of the Rio Grande rift in the southwestern United States
are examples of fault block mountains. Formation of these mountains started approximately
10 million years ago. This diagram shows a simplified cross section—a side view—of the
geology in the vicinity of Albuquerque, New Mexico.
! Interpret the faults in this
cross section. Use the drawing tools to trace the layer of
Pennsylvanian rocks across the full width of the diagram.
Examine the faults to determine the direction of stress.