West Cliff arch - Santa Cruz, California
Posted by: 
hotshoe
N 36° 57.090 W 122° 01.885
10S E 586236 N 4089930
Thin arch extending into the Pacific ocean
Waymark Code: WM54DW
Location: California, United States
Date Posted: 11/09/2008
Views: 26
"One of the most striking features of coastal geomorphology occurs where variations in resistance within the rock formation leads to the formations of small promontories. Where waves attack the flanks of the promontories and there are zones of weakness to be found (such as faults), then a hole may be worn through the sides and a natural bridge formed... What eventually happens is that the hole or arch expands so much that the weight of the overlying rock can no longer be supported and the bridge collapses. The result is a small headland with an offshore rock. Such offshore rocks are known as sea stacks."
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This natural arch just west of Lighthouse Point, east of Natural Bridges State Park, is an example of geology at its most fleeting. It is quite possible that this thin arch will collapse within a human lifetime. There is a seastack visible in the foreground of the photo which is the remnant of a now-gone promontory, but that one dates before the recorded history of Santa Cruz.
Of course, there are signs along the cliff warning people to stay off the rocks, but some people cannot resist.