Mt. Diablo Overlook Earthcache EarthCache
Mt. Diablo Overlook Earthcache
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As an earthcache, there is no “box” or “container” to discover. Rather, with this cache, you discover something about the geology of the area. For more info, consult www.earthcache.org
This vista view gives you a great view of Mt. Diablo, the Suisun Bay, and the US Reserve Fleet. This view is handicap accessible.
Mt. Diablo is an isolated 3,864 feet upthrust peak that is visible from most of the San Francisco Bay Area and much of northern California. Mount Diablo appears from many angles to be a double pyramid and includes many subsidiary peaks, the largest and closest of which is the other half of the double pyramid, North Peak, nearly as high in elevation at 3,557 feet. The mountain is the result of geologic compression and uplift caused by the movements of the earth's plates. The mountain lies between converging earthquake faults and continues to grow slowly. While the principal faults in the region are of the slip-strike type, a significant thrust fault (with no surface trace) is found on the mountain's southwest flank. The uplift and subsequent weathering and erosion have exposed ancient oceanic Jurassic and Cretaceous age rocks that now form the summit. The mountain grows from three to five millimeters each year.
Mt. Diablo is a double pyramid and some say that it resembles a volcano.
Mt. Diablo is a geologic anomaly located approximately 30 miles northeast of San Francisco. The upper portion of the Mountain is made up of volcanic and sedimentary deposits of what once was one or more Island Arcs of the Pacific Plate dating back to the Jurassic and Cretaceous Periods. During this time, the Pacific Plate was subducting (moving beneath) the North American Continental plate and these deposits were scraped off the top and accreted (smeared/stacked) onto the North American Plate. This resulted in the highly distorted and fractured Basalt and Serpentine of the Mt. Diablo Ophiolite and Metasediments of the Franciscan Complex around the summit. East of the subduction zone, a basin was filling with sediment from the ancestral Sierra further to the east. Up to 60,000 feet (18,000 m) of sandstone, mudstone, and limestone of the Great Valley Sequence were deposited shortly thereafter. These deposits are now found faulted against the Ophiolite and Franciscan deposits.
Since pre-recorded history, continental deposits have been periodically laid down and subsequently jostled around by the newly-formed San Andreas Fault system, forming the Coast Ranges. More recently (4 million years "rock time") local faulting has resulted in compression, folding, buckling, and erosion, bringing the various formations into their current juxtaposition. This faulting action is ongoing and will continue to change shape of Mt. Diablo, along with the rest of the Coast Ranges.
The summit area of Mt. Diablo is made up of deposits of gray sandstone (graywacke), chert, oceanic volcanic basalts (greenstone) and a minor amount of shale.
Logging Requirements:
Send the answers to #1-#5 to me through my geocaching profile.
1. List the name “GC20WYY Mt. Diablo Earthcache” in the first line of your email. Also, list the number of people in your group.
2. Based on the view and your reading, is Mt. Diablo the result of volcanic or fault action?
3. Based on your reading of this description, where did the peaks of Mt. Diablo originate?
4. Contrast the “shape” of Mt. Diablo to the other hills/mountains visible from this point. Be able to list at least three DISTINCT geological differences in your note to me.
5. List the elevation at GZ. Based on your reading, how far BELOW the summit are you at this point?
6. (Per current gc.com guidelines, photos are no longer allowed to be required. HOWEVER they are encouraged, since they can help clarify that you have visited the location if your other logging requirement answers are vague). Post a picture of yourself and your GPS with your log that shows Mt. Diablo or the Reserve Fleet behind you. Failure to post a picture will get your log deleted!
I will only respond if you have incomplete logging requirements. Go ahead and log your cache
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Treasures
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