Mount Diablo State Park: Encyclopedia II - Mount Diablo State Park - Natural history

Mount Diablo State Park - Natural history

Mount Diablo State Park - Geology

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. The uplift and subsequent weathering and erosion has exposed ancient oceanic Jurassic and Cretaceous age rocks that now form the summit. 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.The hard red Franciscan chert is sedimentary in origin and rich in microscopic radiolaria fossils. In the western foothills of the mountain there are large deposits of younger sandstone rocks rich in seashells, severely tilted and in places forming dramatic ridgelines. There are deposits of glassmaking grade sand and lower quality coal to the north of the mountain, which were formerly mined in the 1800s and early 1900s, but are now open to visitors as the Black Diamond Mines regional preserve. Guided tours of sand and coal mines are provided here.

Mount Diablo State Park - Vegetation

The park's vegetation is mixed oak and open grassland country with extensive areas of chaparral and a number of endemic plant species, including substantial thickets and isolated examples of poison oak. It is best to learn to the characteristics of this shrub and its toxin before hiking on narrow trails through brush and to be aware that it can be bare of leaves (but toxic to contact) in the Winter. At higher altitudes there are stands of Knobcone pine, Foothill pine, and Coulter pine (for which the park marks the northern extreme of the range). In 2005, the Mount Diablo buckwheat, thought to be extinct since last seen in 1936, was rediscovered in a remote area of the mountain.

[[Image:]]===Wildlife=== All vegetation, minerals and wildlife within the park are protected and it is illegal to remove such items or to harass any wlink titleildlife.

Commonly seen animals include Black-tailed Deer, California Ground Squirrels, Fox Squirrels and Gray Foxes; many other mammals including Mountain lions are present. It is the chief remaining refuge for the endangered Alameda Whipsnake. There are also exotic (non-native) animals such as the Red Fox and Opossum, the latter being North America's only Marsupial.

In September and October you may encounter the male Tarantula spider (fearsome in appearance but harmless if undisturbed) as he seeks a mate. More dangerous are black widow spiders, far less likely to be encountered in the open.

Of special note as a potential hazard is the Northern Pacific Rattlesnake. While generally shy and non-threatening, one should be observant and cautious of where one steps to avoid accidentally disturbing one.

There has also been an increase in the Mountain lion population in the larger region and one should know how to respond to these animals if encountered. Please see the mountain lion safety tips in the Mountain lion article.

One should avoid ground and brush contact to avoid fleas and ticks and the various diseases that they may transmit.

Mosquitos have always been somewhat hazardous in this area as they have been known to carry western equine encephalitis, caused by a virus dangerous to humans. With the recent spread into the counties around Mount Diablo of the recently introduced West Nile virus, mosquitos are now far more hazardous, as this debilitating and frequently fatal disease is carried by (and can be fatal to) bird populations. Mosquitos are particularly active for about two hours after sunset and can be present in large numbers near creeks and during spring and fall wet seasons and after the rare summer rainfalls. Insect repellant containing the chemical DEET is recommended.

Adapted from the Wikipedia article "Natural history", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki