City of Rocks Earthcaching
At the posted coordinates, you'll be standing near Camp Rock which has some historical interest. If you look to the North and West, up the road, you will see a very distinctive rock formation with a pointy rock protrusion on its summit: Kaiser Helmet. In the geologists vernacular, the rock protrusion is called a Pickelhaube. A pickelhaube is an erosional remnant of a case hardened surface that protects the softer rock underneath. The hardened layer has the result of slowing the erosional effects of weather from on the summit of this particular rock, resulting in its distinctive pointy top.
Not surprisingly, most pickelhaubes in the Reserve are covered with bird droppings, and some geologists have speculated that this *covering* of bird droppings has also slowed the effects of erosion.
The process of "case hardening" has been one of much debate amongst geologists. Many suggest that rocks are case hardened by the deposition of chemical weathering products left behind when water evaporates from the surface. In the process, rainwater invades the surface along microfractures and grain boundaries and chemically weathers the minerals. Soluble weathering products are then drawn upward and deposited when water evaporates from the surface. This suggests that case hardening may be the result of external forces, carried by wind and rain.
Others argue that biochemical precipitation of silica by lichens, which thrive on the rocks in this area, use organic acids to leach nutritive elements, such as iron and potassium, from mica and feldspar minerals and leave behind a deposit of silica more resistant than the original minerals.
On the other hand, it may be that all these processes play a role in crust formation.
Logging Requirements:
1. From the posted coordinates, how many pickelhaubes can you see on the summit of the Kaiser Helmet.
2. Are there any formations in the immediate area that also have pickelhaubes on their summits.
3. Do you see any evidence of crust formation on the Kaiser Helmet, or Camp Rock behind you.
References:
Etched In Stone: The Geology of City of Rocks National Reserve and Castle Rocks State Park, Idaho; Keven R. Pogue
Geologic Interpretive Trail, City of Rocks National Reserve; A self guided journey to discovering secrets in the rocks of City of Rocks, Prepared by Idaho Department of Parks and Recreation and the National Park Service.