- In one paragraph, explain the process that takes place (what is happening) and the possible landforms that can result at divergent continental-continental plate boundaries.
As we know the earth’s crust is made up of several huge slabs called plates. At divergent boundaries new “crust” is created as two or more plates pull away from each other. When a diverging boundary occurs on land a “rift valley”, or separation will arise, and over time that mass of land will break apart into distinct landmasses and the surrounding water will fill the space between them. One of the best examples is that of Iceland. Iceland is splitting along the Mid-Atlantic Ridge which is a divergent boundary between the North American and Eurasian Plates. To be more specific, the North American plate is moving westward while the Eurasian plate is moving eastward.
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As a result of this divergence new crust is created on both sides of the boundary. The creation of new crust adds mass to Iceland, it also creates a rift along the boundary. It is predicted that Iceland will break apart into two separate landmasses and the Atlantic waters will fill the widening and deepening space between the landmasses (platetectonics.com).
- In one paragraph, explain the process that takes place (what is happening) and the possible landforms that can result at convergent continental-continental plate boundaries.
Convergent continental-continental plate boundaries result when two continental plates collide with each other. As a result of the convergent plate boundaries, landforms such as a huge mountain range can result if neither continental plate wants to be subducted, and they are pushed up. A very good example of this kind of plate movement is the convergence and collision of India into Asia that occurred over 50 million years ago. This resulted in the Eurasian Plate lifted up and overrides the Indian Plate. After the collision, the slow and continuous convergence of the two plates over millions of years has pushed up the great Himalayas and the Tibetan Plateau to their current heights (platetectonics.com). Geologists find that the Himalayas are growing at a rate of about 2.4 in/6.1cm per year (Extreme Science).
- In one paragraph, explain the process that takes place (what is happening) and the possible landforms that can result at divergent oceanic-oceanic plate boundaries.
At divergent oceanic-oceanic plate boundaries, plates move apart as magma rises to the surface from the asthenosphere. The main features of this are the formation of mid-ocean ridges, rift valleys, volcanoes, and few earthquakes. The magma solidifies to form rock, which attaches to the moving plates. The margins of divergent plate boundaries are marked by mid-oceanic ridges in the oceanic crust. An example of divergent oceanic-oceanic plate boundary occurred, during the process of separation of South America from Africa. Another example is the Mid-Atlantic Ridge and rift valley of East Africa (Maybin).
- Explain the process of mass wasting including what it is, what prompts it, and how the angle of repose is a factor.
Mass wasting is also called landslides. It is defined as the down-slope movement of sediment and/or rock due to gravity. In the term mass wasting the “mass” part of the name implies that a somewhat coherent grouping of sediment/rock begins moving downward due to the gravitational effect. This in combination with some triggering mechanism such as an earthquake or rapid erosion of the base of a slope causes mass wasting.
The “wasting” generally means that a cliff or mountain slope is diminishing in size, or wasting away. Mass wasting can either occur all of a sudden with tremendous destructive force or very slowly with the only minute change of Earth’s surface over a period of several years. Therefore, mass wasting can result in alterations in the landforms. For instance, over a period of time, it can reduce a tall mountain to a mound of low rolling hills, or sometimes it may widen a narrow canyon into a broad stream valley (Introduction to Mass Wasting).
When explaining mass wasting technically, the angle of repose plays a major role. As mentioned above, for a landslide to occur, it has to be acted upon by the force of gravity as well as friction. It is said that the forces of gravity and friction are in balance at the angle of repose which is the maximum slope angle that unconsolidated or loosely bound materials can maintain. Therefore, at angles steeper than the angle of repose, friction is not adequate to counter the gravitational effect and result in mass wasting. On the other hand, at angles less than the angle of repose gravity cannot overcome friction and mass wasting does not occur and sediments keep accumulating (myweb.cwpost.liu.edu).
- Explain how the coastline represents the intersection of the 4 spheres of geography. Be specific!
Coastline areas are areas where land and water together with air and the elements of the biosphere join to create a unique environment with a distinct structure, diversity, and flow of energy. They include coral reefs, mangroves, salt marshes, islands, and estuaries and are home to many different types of plants and animals. The lithosphere is the solid, rocky crust present in the bottom part of the oceans. The lithosphere covers the entire surface of the earth from the top of the mountain to the bottom of the oceans. The hydrosphere is composed of all of the water and is the most important part that makes up the coastline and includes the oceans, rivers, lakes, and even the moisture in the air.
The biosphere is composed of all living organisms the plants, animals, the microorganisms, and is an important part of the coastline. The atmosphere comprises vital gases such as oxygen, nitrogen, carbon dioxide, and other gases in the body of air that surrounds the planet and also forms the immediate layer just above the water bodies. All these four spheres i.e. the lithosphere, the hydrosphere, biosphere, and atmosphere are together seen in the coastline and therefore coastlines are called the intersection of all four spheres of geography.
Extreme Science World Famous Extremes, . Web.
Introduction to Mass Wasting, a CSU Long Beach, Department of Geological Sciences web site, . Web.
Maybin A.H. Earthquakes, South Carolina Department of Natural Resources Geological Survey, . Web.
myweb.cwpost.liu.edu Mass Wasting and the Angle of Repose, . Web.
platetectonics.com The Story of Plate Tectonics, . Web.