Grand Canyon; South Rim.
20th c American Topographical View
Hubert A. MCCLAIN
(Protection. Kansas, 1909 - 1994, Long Beach. California)
The first Europeans arrived here in 1540. The spectacular stepped topography of the Grand Canyon is caused by alternating layers of hard limestone and soft shale, the limestone forming vertical cliffs and the shales the intervening sloping surfaces. These rocks were laid down in ancient seas several hundred million years ago.
MCCLAIN Hubert A. | Grand Canyon; South Rim. | | American |
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