Cat Hills Volcanic

The Yellowstone volcano is very active volcanic system which requires much observation. The geysers, mudd pots, hotsprings and steam vents are all examples of the heat from molten rock of a volcano. For many years the Yellowstone volcano could not be located. There is not obvious signs of a volcano, but scientists looked for other clues. Rhyolite is present in a location that has pinetress and many mosquitoes can be found due to the lakes that have formed. Rhyolite is a very violent eruption, due to the high silica content,  it flows slowly, like honey, and tends to pile up and form lava

Anpother factor that can have an impact on the level of hazard posed by a volcano is the type of plate margin on which it occurs. Volcanoes occuring at constructive plate boundaries are usually much less violent than those occuring at destructive plate boundaries. This is because the magma produced by plates moving apart is Basic, and therefoe has a low viscosity, allowing it to flow easily. The lava is produced from a central vent or fissure and erupts regularly but not usually violently. Also,constructive plate boundaries are often found under the sea and create submarine volcanoes, such as along the Mid-Atalntic ridge, so pose few threats to humans. As a result, the hazards posed by volcanoes at constructive plat eboundaries is relatively low. However, the subduction of one plate under another at destrctive plat eboundaries can form an acidic magma chamber, due to the build up of intense heat. Acidic magma is very viscous and resisitant to flow, meaning that there is often a huge build up of pressure, which can result in very violent and dangerous eruptions involving ash and pyroclastic flow. This can pose a a serious hazard. Pyroclastic flowsa are extremely dense, containing toxic gases at very high temperatures, and can move at speeds over 100km/h. The consequences of such an unpredictable hazard can be extremely seruous

The volcanoes are located where there is a divergence or convergence in the tectonic plates and bring their lava from the deepest of the terrestrial mantle. The materials and explosions of these ginates represent a constant risk in the places inhabited by the human being, nevertheless the people ususually live in these areas no matter the risk. On the other hand the volcanos can change the geology of an impressive form, or to cool the temperature of the earth, or to darken the sky. The scientific community increases its efforts to try to understand better what happens in volcanoes, however it is impossible to predict these conditions.

The youngest of these rocks are dated at about 220,000 years ago. Rhyodacties and quartz latites in the modern caldera area extruded from about 320,000 years ago to 260,000 years ago, and then silica-rich rhyolites at Glass Mountain northeast of the caldera erupted from about 210,000 years ago to 80,000 years ago. The scattered distribution of the initial mafic eruptions indicates that they were erupted from the mantle, while the slightly younger domes and flows were from a deep-crustal source. The youngest rhyolite eruptions erupted at the northeast rim of the caldera at Glass Mountain and were the first activity of the silicic Long Valley magma chamber (Bailey, et. al., 1989).

Copper-zinc (VMS-type?) mineralized zones were discovered in Archean volcanic rocks in the southern part of North Williams Township by Metron Explorations Limited in 1970. The mineralized zone and surrounding area were evaluated with a HLEM survey and drilled with 2 DDHs (totaling 61.3 m) that did not intercept significantly mineralized rocks (Willars, 1971).

Next, we can see that the rock displays a subtle porphyritic texture with plagioclase comprising the phenocrysts. The overall texture of the surrounding groundmass is granoblastic equigranular. Under thin section we also see a weakly defined foliation evidenced in the preferential alignment of actinolite grains and to a lesser extent chlorite grains. Undulose extinction is also observed in quartz indicating the rock was subject to deformation. The normalized quartz, alkali-feldspar, and plagioclase (QAP) values of this rock indicate that it is classified as a grano-diorite according to the IUGS QAPF classification system which is consistent with the hand sample interpretation.

Cenozoic sedimentary rocks predominated to the west and east of the central mountain while plutonic rocks predominated in the peninsular ranges. The irregular contact between these geologic regions reflects the ancient topography of the area. The ancient oceanic crustal plate created an archipelago of a volcanic island. The former's subduction created immense volumes of magma. This resulted to the congealation of plutonic rock in the crust. The local rocks that existed before the tectonic forces uplifted, and erosion capped the deeply buried plutonic rocks that formed a steep and rugged mountains coastline, similar to that present one, which in the west coast of south America.

Imagine a single event that can kill 57 people and 7000 deer and elk. Snap trees like a toothpick, and turn the sky grey for 15 days. Now, stop imagining, Mount St. Helens, in the Cascade Range of southwestern Washington State, erupted. On May 18th,1980. According to (Campbell 371), “At least $1 billion in economic damage was reported”. The eruption of Mount St. Helens took many lives, and devastated America. Mount St. Helens destroyed more than 230 square miles of ancient forest.

Feel free to stretch, it's been a long ride. We will be stopping by a restaurant later to get some lunch. In front of you, you can see Humphreys Peak, the tallest mountain in the San Francisco Peaks. The San Francisco Peaks is actually a volcanic mountain range and is part of the San Francisco volcanic field. The peaks were once a stratovolcano but is now eroded and are the remains of the volcano. It is the only stratovolcano in the San Francisco Volcanic Field. The tallest mountain, Humphreys Peak, is about twelve thousand, six hundred and thirty-three feet in elevation, which is also three thousand, eight hundred and fifty-one meters tall. In fact, Humphreys Peak is the tallest point in all of Arizona. Also in this area, are more than six hundred volcanoes. Most of the volcanoes found here are basalt cinder cones. These volcanoes are relatively small. They are also usually less than one thousand feet in elevation. Another fact about these basalt cinder cones is that they are formed within a range of a couple of months to a couple of years. The San Francisco Volcanic Field also has several lava domes. Lava domes are formed by dacite and rhyolite magmas. Both of those types of magma are very rich and high in silica. So, as a result, the dacite and rhyolite magmas are very viscous and thick. As a matter of fact, the magmas are so viscous is thick that when volcanoes erupt, the magma tends to pile up and form very steep sided masses, which are the domes.

Complete this week’s lab by filling in your responses to the questions from Geoscience Laboratory. Although you are only required to respond to the questions in this worksheet, you are encouraged to answer others from the text on your own.

A period of volcanism resulted in igneous intrusions within the Raton Basin-Sierra Grande Uplift Province that was sourced from the upper mantle about 26. 6 billion years ago and is associated with parallel dikes and sills (Higley, 2007). Igneous rocks are common within the Raton Basin and include Tertiary dikes and sills that range in age from 6.7 to 29 5 million years ago (Flores and Bader, 1999). One of the main differences between dikes and sills is that dikes are longer lived magma conduits and sills are features that form when magma is in neutral buoyancy with the surrounding rock (Rooper et al., 2006). These volcanic events are associated with hydrothermal alteration of coal within the basin (Higley, 2007).

Many millions of years ago the Sierra Nevada was filled with ocean water until sediments began collecting and formed mountain ranges. Over a large period of time, the mountains began to wear out and became immersed in the ocean once again. Many different particles and materials began to make layers and created the first mountain system. After the Jurassic era, “…new strata were folded and crumpled and invaded by molten granite from below” (Beatty, 1943). A large

In the eastern part of the plateau most of the carbonate strata is Fredericksburg and Washita rock (Barker and Ardis 1996, 5). The plateau is dominated by a flat undistinguished plain, with the exception of the caprock mesas, the broad alluvial fans and the Balcones fault zone (Barker and Ardis 1996, 5). During the Paleozoic era the Ouachita Orogeny tectonic event occurred depositing marine sea deposits of upper Permian sediments and evaporates into the Permian basin, which is above parts of the Edwards-Trinity plateau aquifer (Anaya 2001, 107). Another prominent structural feature is the Llano uplift which is comprised of Precambrian rock mostly granite, located in the northern Hill Country area (Anaya 2001, 107). The Balcones fault zone was created from tensional stress from the uplift and deposition of sediments into the Gulf of Mexico, along the Ouachita belt, forming the faults by displacing the sediment 900 to 1200 feet (Anaya 2001, 109). The Edwards-Trinity plateau has two regional confining layers, Navarro-Del Rio, which confines the Edwards aquifer, and the Hammett that confines the Trinity and the Edward-Trinity aquifers (Barker and Ardis 1996, 2). The Navarro-Del Rio confining unit is regionally continuous within the Balcones Fault Zone; it is comprised of Buda limestone, Navarro Group,

These rocks grade abruptly northward into a marine geo-synclinal facies up to as much as 6,000 feet thick in the Las Vegas sub-basin. The Magdalena Group is missing from the Cimarron arch, but it most likely present in the western part of the northern Raton Basin. Orogenic debris of the Sangre de Cristo Formation of Pennsylvanian and Early Permian age was derived mainly from the San Luis uplift, filled the Rowe-Mora and Central Colorado basins, and lapped onto Precambrian rocks of the other bounding uplifts. The Sangre de Cristo Formation is 700-3,500 feet thick at the south, and 6,000-9,500 feet thick at the north (Baltz 1965).

Lava flows of rhyolite and basalt have flowed through parts of Yellowstone as recently as 70,000 years ago. These lava flows destroyed everything in their paths while moving slowly at a rate of a few hundred feet per day, flowing months, or sometimes even several years. They are thick and cover as much as 130 square miles. They have nearly filled the Yellowstone Caldera, and spilled beyond the caldera’s border. These lava flows are responsible for forming four of the nine named plateaus in