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 1st Expository Text Mesas: A Giant’s Table I’ve only seen them in books and on the internet but they are very popular as scenery of cowboy movies because this type of landform does not exist in Lebanon. Mesas have steep drops and flat tops. The most famous ones are in the south west of the United States. They are rare to find. Formation How are mesas formed? They are formed by weathering and erosion of horizontally layered rocks that have been uplifted by tectonic activity. Erosion means the transportation of sediments and weathering means the breakdown of rocks. Different types of rock to resist weathering and erosion at different rate. The weaker kind of rocks erodes faster, leaving the more resistant kind of rocks standing. This is called differential erosion. The hard rock’s erode slower than soft rock. Lava flows and sill often form the top or caprock of a mesa, and these are very hard rocks. The less resistant rock layers are mainly made up of softer rock that weathers and erodes more easily. Mesas are only formed by wind erosion acts like sand sandpaper it is the sand that gets carried away in the wind. Where are they found? Mesas are found in dry rocky deserts, because they need strong wind and sand. They need sand because the wind carries the sand and the sand erodes the rock. What are they used for: Mesas are used as a back drop in cowboy movies. They thought cowboys lived around them. They also use them for rock climbing. Climbers like to climb them because they are steep and when they reach the top there is a nice view. What lives on a mesa? One organism associated with mesa is a Road Runner. Road Runners live in deserts. There is a cartoon about a road that runs around in deserts and sets traps on mesas. I think mesas will get smaller and smaller and smaller by erosion until it is gone and new ones will get formed.
Article posted February 17, 2011 at 04:28 AM • comment • Reads 2631 • see all articles |
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