Q1. Describe in detail how the rocky Mountains were formed. What is the origin and character of the Green River formation? How did the Rocky Mountain orogeny affect the Sierran Arc? Are the Rockies still growing?
The Rocky Mountains were formed in the course of intense activity of plate tectonics when the North American plate moved in a westerly direction and the Pacific plate moved northwards. During the movement of the Pacific plate, the North American plate forced some of its crust down to the earth’s core. Intense forces that squeezed the existing landmass resulted in the first orogeny (Columbia Mountains) that accompanied the collision. The second orogeny that resulted in the formation of the Rockies occurred when the shock wave that was moving east cracked big rocks and slid them over their neighbors.
The green river formation constitutes many basins that came into existence due to the Rocky Mountains being uplifted during the lower tertiary. It is characterized by its heterogeneous composite of lakes with differences in ecology, timeframe, geological characteristics, and flora and fauna. In addition, it is famous for its fish fossils. The Rocky Mountain orogeny formed the Sierran arc by spewing lava and ash from volcanoes during plate collisions.
Q2. What is the Basin and Range province? Where is it? Explain the processes involved in its formation. Is it still active?
The basin and range province is found in the state of Nevada and refers to a big region of faulted mountains and flat valleys that alternate from North to South. It was made because of the earth’s crust thinning, stretching, and finally breaking into several mountain blocks that rotated in part of their initial horizontal positions. Currently, it is not active even though some areas still show signs of activity such as the release of carbon dioxide.
Q3. There are at least 3 reasons for Cenozoic volcanism in the American West. Describe the causes for each and give examples of the volcanic regions that developed from these processes.
Cenozoic Volcanism in the American West is caused by changes in tectonic setting, normal faulting, and eruption of immediate composition through the orogenic or slightly stable crust. Volcanic regions that developed include the Zuni Bandera field and a cluster of fields in Northwestern Catron County.
Q4. How were the Hawaiian Islands formed? Why are they not in a straight line? What is the oldest/youngest island? Are they all above the water? Why or why not?
The Hawaiian Islands were formed when a hot spot occurred in the middle of the Pacific Plate. In fact, while the plate was moving over a hot spot, the hot spot itself remained fixed leading to the formation of the Hawaiian Islands. The Islands are not arranged in a linear manner because, during their formation, the Pacific plate moved over a stationary hotspot on which they are formed. The islands in the northwest are older and smaller because they were exposed to erosion. Lastly, the biggest and youngest islands are Hawaii Islands.
Q5. Why does the passive margin of the Gulf of Mexico possess such thick sediments? What is the origin of the salt domes? Why do they develop and why are they of economic importance?
The passive margin of the Gulf of Mexico possesses thick sediments that provide good conditions for organic matter to accumulate and mature. Salt domes are formed due to gravitational forces, tectonic forces, or a combination of both occurring simultaneously or one after another. They develop because either they are buried at a depth greater than 2000ft or the salt is under pressure. They are economically important because their impermeability leads to the formation of excellent traps for hydrocarbons.
Q6. Trace the change of climate throughout the Cenozoic. What caused the changes and how did life forms evolve in response to changing conditions- what adaptations were advantageous?
Climate changes in the Cenozoic were caused by changes in land-sea distribution, orography, ocean heat transport, and carbon dioxide. Life forms evolved by growing adaptive features suitable to survive in the environment such as small size in animals and teeth.
Q7. What are possible triggers for the Pleistocene Glaciations? What are the most likely reasons? Explain the Milankovitch Cycles.
The possible triggers of the Pleistocene Glaciations include a combination of oceanic circulation, continental positions, fluctuations in solar energy, and the earth’s orbital cycles. Milankovinch cycles refer to variations in the solar radiation reaching the earth due to the repeated changes in the motion of the earth.
Q8. How have glacial-interglacial oscillations affected coastal and fluvial (river) landscapes” How has this influenced biogeography? What types of landforms are characteristic of glacial terrane? What is an isostatic rebound? How are the Great Lakes and Finger Lakes related to glaciation? What happened to Lake Missoula?
The four major glacial episodes are namely the Kansan, the Nebraskan, the Illinoian, and the Wisconsin glacial stage. They each occurred during the last years of the Pleistocene, which is approximately 110,000 to 12000 years ago.
Glacial-interglacial oscillations affect coastal and fluvial landscapes by producing dramatic landscapes through erosion and sometimes deposition by glaciers. The resultant effect is the existence of nearly rugged mountain landscapes. The types of landforms that are characteristic of the glacial terrane include the drumlin, cirques, kames, and kettles. Isostatic rebound is a situation in which land elevations rise gradually and then eventually spring back after several years of continental glaciers’ crushing.
The Great lakes and the Finger Lakes were both formed because of glacial activity. The great lakes were formed when glaciers moved and eroded the landscape resulting in the formation of deep basins and valleys. On the other hand, the Finger Lakes are formed when glacial sediment dams rivers and streams. Glacial Lake Missoula existed in Montana about 12000 years ago. There was a weakening of the rising water that was found behind the glacial dam leading to the water bursting and creating a catastrophic flood that affected Washington, Idaho heading towards the Pacific Ocean. For many centuries, the lake filled and emptied in repeated cycles until it no longer existed.10
Q10. What is a hominid? When did hominids first appear? Describe at least 5 species of hominids. When did modern humans first appear?
Hominids refer to great apes or primates. The first one appeared 20 million years ago. Species of Hominids include Sahelanthropus, which possibly is the first of the hominid species with small canine teeth and small brain size. It walked on two legs instead of four and the shape of its face was sloppy similar to that of a chimpanzee. Australopithecus afarensis is another hominid that existed. There was no evidence of tools they used probably., They had a diet much like modern chimps and lived in an environment where fruits would have been abundant. Homo habilis had a brain size 50% larger than the contemporary species. The brain also had structures that imply language areas; first to make stone tools. Homo erectus was the first hominids to have populations leave Africa and occupy Europe.
In addition, Homo erectus was the first hominid to use fire, and stone tools but made better ones and over time showed technological evolution. Homo sapiens, on the other hand, had the following characteristics: an average brain size, a chin that was discernibly prominent, a sharp forehead, and a much more graceful skeleton. During this time, their tools had also evolved to become more sophisticated and included among others, bones, and antlers. They also implemented tools in the making of items such as clothing, engravings, and sculptures. Homo sapiens also had the ability to capture animals by the use of nets, hooks on fishing, and harpoons. Their artwork had undergone a considerable change to include beads, carvings made from ivory that depicted both animals and human beings, musical instruments, and figurines that were modeled from clay. Modern humans first appeared nearly 200000 years ago as Homo sapiens.