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To get credit for this earthcache please message your answers to me for the following questions:
1. What type of rock primarily makes up the rocks in this formation?
2. What is the origin of these rocks? Igneous, Sedimentary or Metamorphic.
3. Describe the rock face and what colors you see?
You can log the cache; but if no satisfactory answer is sent, your log will be removed. The information below, the sign at the Vista Observation Site, and your observations will help answer the questions.
Geology of the area
This location is in the heart of the Sacramento Mountains. The sedimentary layers are mostly massive limestone layers of the San Andreas, and sandstone and shale of the Yeso Formations. Gypsum layers are also exposed at few places. These formations were deposited in the marine environment during the Pennsylvanian and Permian Periods (about 280 million years ago). Sedimentary rocks are sparsely exposed due to the dense vegetation in the area. The sedimentary rocks can be easily observed at the Tunnel Visa area and give an excellent view of Pennsylvanian and older sedimentary rocks and faults.
Igneous Rocks
Igneous rocks are crystalline solids which form directly from the cooling of magma. This is an exothermic process (it loses heat) and involves a phase change from the liquid to the solid state. The earth is made primarily of igneous rock - at least at the surface where our planet is exposed to the coldness of space. Common igneous rocks are granite, basalt, and pumice.
Sedimentary Rocks
Sedimentary rocks are formed from deposits of pre-existing rocks or pieces of once-living organism that accumulate on the Earth's surface. If sediment is buried, it becomes compacted and cemented, forming sedimentary rock. These rocks often have distinctive layering or bedding and create many of picturesque views. Common sedimentary rocks are limestone, sandstone, and shale
Metamorphic Rocks
The metamorphic rocks get their name from "meta" (change) and "morph" (form). Any rock can become a metamorphic rock. All that is required is for the rock to be moved into an environment in which the minerals which make up the rock become unstable and out of equilibrium with the new conditions. In most cases, this involves burial which leads to a rise in temperature and pressure. Common metamorphic rocks include slate, gneiss, quartzite and marble.
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