1. Canyon de Chelley National Monument is located in Arizona and Utah. It has sandstone canyon walls that were cut open mainly by water erosion. The canyon walls measure one thousand feet in some places. Three layers of limestone and sandstone called Entrada/Wingate/Kayenta make the walls beautiful due to blending shades of red and white. The area is about 83,800 acres. The canyons, gorges and ravines were made by years of water erosion. On the east side of the park sit the Chsuka Mountains. The headwaters that form in the mountains rush down to form the canyons. The most amazing geological structure in the park is the Spider Rock which consists of two tall rock towers approximately 750 feet and 800 feet in height. The Defiance Plateau though was formed by earth crust uplift. It is made of layers of hard sandstone alternating with layers of softer layers. Wind erosion erodes the soft layers creating the interesting shapes of the ledges, cliffs and towers. The Anasazi lived on the canyon walls between layers of sandstone where caves and ledges provided space. The rocks forming the floor of the canyon are the oldest. They were formed about 2 billion years ago. The younger rocks at the top are about 250 million years old.
2. Desertification happens to perfectly good land when it is not carefully used. Many places that are deserts now, were good places for agriculture years ago. The problem starts with bad management of water and the soils plus overpopulation puts extra stress on an area. Crops may be irrigated until the water on reserve runs out and not enough rain falls to fill up the reservoirs that hold the extra water supply. Tropical forests can turn into deserts if people cut down the trees. The trees hold in the moisture and the tree roots hold the soil. When the trees are removed the water evaporates or runs into streams or rivers away from the area. That means that there is no water and erosion speeds up the desertification process by carrying away good soils from the tropical rainforest floor. People are suffering very badly in the southern Sahara Sahel region where desertification has been happening very rapidly. Africa has been hit really hard in other areas too including Mali, Burkina Faso and Senegal. People die and have to migrate to other areas. The Amazon rain forest is probably the most famous area where desertification is happening. That’s because trees are cut down to make room for cattle ranching.
3. The Department of Geosciences Environmental Studies Laboratory has an interactive map visualization tool on the Internet. It is a digital elevation model designed to visualize the impacts of what will happen to coastal areas due to sea level changes from global warming. The impact of a 1 meter rise in the sea level is colored reddish-brown. The impact of a 6 meter rise is in yellow. The map below shows the impact on the coast of South Carolina so the results can be compared. The southern border of South Carolina with Georgia will be degraded by erosion along the edges of the estuary. The estuary will be made larger with only a 1 meter rise of the sea level. Interstate 95 and Interstate 16 take people to Savannah now but with a 1 meter rise in sea level the parts of the highways will be underwater. A six meter rise in sea level will cover Hilton’s Head entirely and the whole eastern coast of South Carolina will be eroded and underwater up to about 25 miles inland. That means Interstate highways 95 and 16 will end further inland at the new coastline of the Atlantic Ocean. Infrastructure, homes and harbors will be destroyed and take different shapes if the sea level rises 1 meter. If it rises 6 meters a new coastline will result with the ocean covering the low lying coastal area.
(1) This photo was taken about 100 years ago of a sea arch named Jump-Off Joe. It was located Nye Beach close to Newport, Oregon. (2) The shape is called a sea stack which is a pillar of rock found at the edge of coastlines all over the world. At one time it was even larger but over time waves of the ocean slowly shrinks the sea stack as you can. (3) In this series of photos you can see the strength of water to cause erosion. First the softer parts of the structure are washed away and the sea stack changes shape. (4) Near the ground a small arch forms that grows bigger and bigger. The sea wears down the top of the structure. (5) Finally the broken arch erodes into smaller pieces. The parts of the sea stack on the beach are washed away.
Works Cited
DGESL: climate GEM. Mapping areas potentially impacted by sea level rise. 2012 March 21. Web. 2012 July 20. http://climategem.geo.arizona.edu/slr/us48prvi/index.html
Exploring Earth ES1606 Examine an example of wave erosion. (n.d.) Web. 2012 July 20. http://www.classzone.com/books/earth_science/terc/content/visualizations/es1606/es1606page01.cfm
