Comb Ridge, near Kayenta, Arizona
Comb Ridge, near Kayenta, Arizona, is a beautiful
example of a monocline, a single-limbed fold. Monoclines are classic
landscape features of the high deserts of the Colorado Plateau in
the American Southwest. These folds were formed by dip-slip movement
of rocks along deeply-buried faults about 65 million years ago,
as tectonic forces compressed the crust and uplifted the Rocky Mountains
farther east. They stand as evidence that continental regions that
are seismically quiet now may have experienced deformation and earthquake
activity in the geologic past. The view is to the east. Note the
east-west fractures, visible near the center of the image, which
formed when the relatively brittle rock was folded.
Contributed by Steven Semken, Arizona State University
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