Geology and the Glacial History of the SW British Columbia Region - Research Paper Example

Geology, Geomorphology, Tectonic Setting, and the Glacial History of the SW British Columbia Region Introduction The physical backdrop of British Columbia is comprised of a large selection of landforms and rock materials. This ranges from the high summits in the Rocky Mountains, to sedimentary Lower Fraser Valley, and molten rock tablelands in the central interior region (Stelling, 2007, p. 13). This article aims to describe and to somewhat explain the distribution of bedrock types, landforms, and surface rock materials that make up the unconsolidated sediments that have been dumped in geologically recent times. Currently, the SW British Columbia landforms and the distribution of surface rock materials are a result of three factors that include rock type, the regions tectonic history, and finally climate. The response of the regions bedrock to weathering and erosion influences the type of associated region landforms and surficial rock materials (Arnaud et al., 2011, p. 14). On the other hand, tectonic history of the SW British Colombia region is the structure of earth movements that have caused the uncultured arrangement and comparative elevation of key topographic features (Siebert et al., 2010, p. 17). Climate regulates weathering, erosion, and deposition of rock landforms, which are geomorphic processes as well as the degrees at which they operate. The history of climatic change is also an attribute in the changing landscape. To analyze the subsequent complex physical landscape of the region, this paper has been subdivided to cover the physical attributes of the region effectively. Geology of SW British Colombia The physical landforms that are created upon a specific type of bedrock are linked to its structural topographies for instance, bedding planes, folds, faults, joints and their mineralogical configuration. Rock structure defines both key landforms and specifics of the landscape. For instance, the vertical sheer-sided parts of Fraser Valley that are at the intersection of the Boston Bar and Lillooet faults, or the bulk of rock fragments on a talus slope is linked to the arrangement of joints and sheet planes on the cliff overhead (Stelling, 2007, p. 43). A geological chart of the SW province illustrates the numerous diverse rock types arranged in a complex pattern for example, the map specifics show intrusive igneous rocks, which are characteristically coarse crystalline in nature. Regardless of the differences in mineralogical composition, these plutonic rock types tend to be related with a specific kind of terrain. These different rock types are structured in a complex range from simple stocks to the huge multifaceted batholith of the Coast Mountains (Miller, 1995, p. 47). These means that the rocks in the SW region are comparatively resilient to weathering as they are comprised mainly of tough minerals made of quartz, hornblende, and feldspar structured as a unified fabric of interconnecting crystals. Consequently, inclines on these rock landforms are usually steep making the topography rugged. Glacially fashioned cliffs survive with little alteration, particularly in enormous or thinly jointed rocks. Joints and faults establish outlines of weakness and are shadowed by cliffs, gorges, and depressions. Tectonic History A brief description of tectonic history is essential in understanding the SW province since the key topographic structures of the region are tectonically managed and numerous mountainous ranges owe their current high altitude to recent fault uplift and not resistance to erosion. Tectonics are established as the major architectural forces in the SW province of British Colombia Southwestern British Columbia known is also recognized as one of the most seismically lively regions in Canada. About 350 earthquakes occur in the region each year that runs from the north end of Vancouver Island to Seattle, Washington U.S. The reason for all this is comes because SW British Columbia is situated above the margin between the oceanic Juan de Fuca Plate and the continental North American Plate. This tectonic margin is also identified as the Cascadia Subduction Zone, which is about 1000 km from the Northern Vancouver Island to the Northern part of California. Research has shown that the Juan de Fuca Plate submerges beneath the North American Plate at about four centimetres per year. Figure 1: Image of the Cascadia Subduction Zone The mountain structures of the SW province have been developed due to several episodes of tectonic activities since late Precambrian time. These sequential episodes have tended to underline the already reputable regions structural character. For instance, two of the great crystalline belts namely the Cassiar-Omineca-Columbia Mountains and the Coast-Cascade Peaks have been the consequence of recurrent uplift, distortion, and igneous intrusion caused by tectonic movements in the area (Price et al., 2007, p. 18). As earlier explained the tectonic activities have been present for a long period of time some of the current physical landscape was developed for the Cenozoic period. Folding and thrusting of geosynclinals deposits to form the Rocky Mountains arose approximately 60 to 35 million years in the past (Hancock, 1989, p. 78). The Coast and Omineca belts also went through re-elevation during this time. On the other hand, during mid-Eocene era, several fissure and shield volcano eruptions shaped the first of the dual sets of lava layers that cover most of the Inland Plateau. After the volcanic eruptions of the mid-Eocene era wide-ranging tectonic uplift followed, subsequently causing different rates of erosion of the surface and its superposed lava layers. It was up warped along the old Coast and Omineca axes and along the Insular Mountains. The erosion surface constitutes the oldest landform that is preserved today (O'Connor et al., 2009, p. 43). Glacial processes modified the large portions of the Interior Plateau only slightly. However, dissection by rivers has been severe around the plateau margins, whilst in bordering mountains, isolated remnants of flat or gently sloping terrain and accordant summit levels are all that remain. Parts of the up- land surface survive on interfluves in the Insular Mountains of central Vancouver Island. Geomorphology of SW British Colombia Geomorphic processes currently and during the Holocene period have been organized in part by the influence of Fraser Glaciation and partly by Holocene era climatic conditions (Panizza et al., 1996, p. 42). Closely following de-glaciation, there was an age of extreme thawing processes when creeks and rivers redistributed most glacial drift, and mass erosion processes altered drift deposits on slopes. Aggradation along streams, alluvial fan deposition, and lacustrine sedimentation occurred at this time. This activity gradually diminished as the supply of easily erodible drift became exhausted. In many valleys, postglacial aggradation was succeeded by a phase of down cutting by streams and rivers. Terraces were cut into moraine, fluvial, and lacustrine sediments. With one or two exceptions, the effects of Holocene climatic change are hard to discern in the British Columbia landscape. Increased warmth and dryness during the Hypsithermal period in south-central British Columbia appears to have induced aeolian processes by causing reduction in vegetative cover (French et al., 1997, p. 54). Sand dunes in Okanagan Valley and other aeolian deposits have been attributed to this origin. In alpine areas, per-glacial and glacial activity seems to have increased during the neo-glacial events described earlier. The Glacial History of SW British Colombia The activities on the Cascadia Subduction Zone fault lines have been documented for ages and are responsible for major glacial movement and landscape change over the centuries (Ehlers et al., 2011, p. 32). In conclusion, the physical topography of British Columbia is made up of a large selection of landscape and rock materials. This ranges from the high peaks in the Rocky Mountains, to sedimentary Lower Fraser Valley and molten rock tablelands in the central interior region. These variations in landscape are because of various physical and climatic changes in the area. In order to understand this land one has to study the geology of south West British Colombia taking to consideration the regions tectonic history, geomorphology, and Glacial History. These aspect give a clear view of these regions topography and hence a comprehensive understanding of the region. Reference list Arnaud, Emmanuelle, Galen P. Halverson, and Graham Shields-Zhou. 2011. The geological record of neoproterozoic glaciations. London: Geological Society. Ehlers, Jürgen, Philip L. Gibbard, and Philip D. Hughes. 2011. Quaternary glaciations - extent and chronology a closer look. Amsterdam: Elsevier French, Hugh M., and Olav Slaymaker. 1997. Canada's cold environments. Montreal [u.a.]: McGill-Queen's Univ. Press. Hancock, P. L. 1989. Current Topics in Structural Geology. Burlington: Elsevier Science. Miller, David M. 1995. Jurassic magmatism and tectonics of the North American cordillera. Boulder, Colo: Geological Soc. of America O'Connor, Jim E., Rebecca J. Dorsey, and Ian Madin. 2009. Volcanoes to vineyards: geologic field trips through the dynamic landscape of the Pacific Northwest. Boulder, Colo: Geological Society of America. Panizza, Mario. 1996. Environmental geomorphology. Amsterdam: Elsevier. Price, Raymond A., James W. Sears, Tekla A. Harms, and C. A. Evenchick. 2007. Whence the mountains?: inquiries into the evolution of orogenic systems : a volume in honor of Raymond A. Price. Boulder, Colo: Geological Society of America. Siebert, Lee, Tom Simkin, and Paul Kimberly. 2010. Volcanoes of the World Third Edition. Berkeley: University of California Press Stelling, Peter. 2007. Fire, faults, and floods: geological field trips in Washington State and southwest British Columbia. Bellingham, Wash: Geological Society of America. Stelling, Peter. 2007. Fire, faults, and floods: geological field trips in Washington State and southwest British Columbia. 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