preview

Ferguson Volcanoe Research Paper

Decent Essays
The volcanoes in the north-south trending cascade province evolved through subduction, addition of exotic terranes, and oblique plate movements. The North American plate edge was located farther east during the Mesozoic era. However subduction created microcontinents and microplates which shifted the plate edge westward.

The first cascade volcanoes erupted 42 million years ago (Ma) forming the older western cascades. It was orientated northwest but rotated clockwise to become the north-south that it is today. Because of the rotation fissured appeared on the east and lots of eruptions occurred on the Columbia River basalt 17 Ma. Subduction and volcanism continued for 25 million years in the older Cascade Range. Magma caused rocks to heat and
…show more content…
The area instead was covered in deltas, swamps, and inlets. Eastern rivers drained into the area. Clay and Peat compacted into a 10,000ft sandstone, shale, and Puget Coal. Basins made from oblique subduction filled the Cascades with thick sandstones and conglomerates. During the Quaternary Period: Pleistocene Epoch the eruptive centers that would create Mount Rainier National Park erupted from 7 to 2 Ma. Mount Rainier was built from material erupting from a central vent. A plug of solidified lava now fills this vent and is exposed in the precipitous east wall of Sunset Amphitheater. Although Mount Rainier is the second highest peak in the conterminous United States, the mountain’s peak was once considerably higher than its 14,410 feet today. The truncated lava flows in the upper part of the mountain slant upward to a former summit that was at least 100 feet higher than the present summit. Three hypotheses have been proposed as reasons for the summit’s removal. Some geologists believe the pinnacle of Mount Rainier was removed by a violent explosive eruption, but fragments from this eruption have not been found. Others believe that avalanches and glacial erosion rapidly ate away the upper part of the mountain. Still others see the former summit collapsing into the central vent when the column of lava temporarily…show more content…
A major eruption melting the ice and snow could send debris flows, pyroclastic flows, and lahars towards Puget Sound and the Seattle/Tacoma metropolitan area. Volcanic hazard mapping has identified areas in the park that could be affected in the future by debris flows, lahars, pyroclastic flows and surges, lava flows, volcanic projectiles, tephra falls, and lateral blasts. Longmire Village and the Cougar Rock, Ohanapecosh, White River, Ipsut Creek, and Sunshine Point campgrounds are all vulnerable to these hazards. Monitoring of volcanic activity is on-going. There is a need for an emergency response plan to address these hazards. The reaction between groundwater and rising gas and steam from the underlying magmatic system creates zones of hydrothermally altered rock. Fumeroles at the summit of the volcano are one result of this reaction. Another result is the largest volcanic ice-cave system in the world at the summit of Mount Rainier. Earthquakes are also geologic hazards associated with Mount Rainier. Earthquakes precede a volcanic eruption although not every earthquake means an eruption is imminent. Other than Mt. St. Helens, Mount Rainier is the mos (Graham)t seismically active volcano in the Cascades. The destruction of cryptobiotic soils and general soil erosion by human impacts are important issues. A
Get Access