Warmup 11/17/15 How do you think something like this could even be formed by tectonic or natural processes? Come up with a theory. (It doesn’t matter if it’s good. Mr. C. just wants you to think!) Objective Tonight’s Homework To see how erosion and deposition can further shape earth’s mountains p 161: review 2, 4, 8

Erosion and Deposition We’ve talked about how mountains can be created, but what about ways of shaping mountains? If we take a large plain and erode it, we can end up with nothing more than a few isolated areas with flat tops and steep cliffs. These are mesas and buttes.

Erosion and Deposition Further erosion can lead to pinnacles – sharp, tall points of rock. Pinnacles are often formed by wind and sand carving a rock away over time.

Erosion and Deposition When a volcano forms, a large area inside it fills with magma. We call this area a magma chamber. When a volcano goes dormant, all the magma in this chamber cools and turns into hard rock. Over time or in a flood, most of the volcano can erode away, leaving only this hardened lump of magma. We call this a monadnock.

Erosion and Deposition But wind and water can do more than destroy. They can also build up mountains! Below is a picture from Great Sand Dunes National Monument here in Colorado. Huge sand dunes have been created by wind carrying sand and depositing it in one area.

Erosion and Deposition Glaciers can also form some amazing features. Below is a picture from Glacier National Park in Montana. During the ice age, glaciers would grow and move between mountain peaks. When they did this, they carved and widened the space between the peaks, creating these very unique “U” shaped valleys.

Erosion and Deposition Most glaciers also push a ton of rocks and dirt in front of them as they move. When a glacier stops and recedes, it leaves behind all this rubble. We call this structure a terminal moraine. These can be found in pretty much every valley that has had a glacier.

Erosion and Deposition Lastly, volcanoes are also created by deposition – the depositing of material to build something up. In this case, lava flows and hardens, slowly building the mountain up until it towers over the landscape.

Work time You have the rest of class to start working on your homework and catching up with anything you may need to work on for this class.

Exit Question What is a monadnock? The rocky outside of an old volcano A hardened bubble of lava from inside a volcano The remains of a volcano that has been split by an earthquake A gigantic plain made of hardened lava Some sort of fish monster None of the above