The contiguous United States are framed by three major bodies of water: the Atlantic Ocean on the east coast, the Pacific Ocean on the west and the Gulf of Mexico to the south. The Pacific also holds the Hawaiian Island chain. The Gulf stretches from Texas to Florida and also touches Alabama, Louisiana and Mississippi.
This Should Help a Little:
A largely semi-arid belt of barren, sandy and rock-strewn land, the Sahel marks the physical and cultural transition between the continent's more fertile tropical regions to the south and its desert in the north. ... The Sahel also suffers from ethno-religious tensions, political instability, poverty and natural disasters.
A weather maps an example of a Model :)
In divergent boundaries, plates move away from one another, often causing volcanic activity. The cooled magma is able to form islands such as the ones on the Aleutian archipelago.
*I don't think any of these are actual types of mountains. <em>Arc contient </em>and <em>Andean</em> aren't even real things.
As for your second question:
There are two main types of rocks in the Earth's crust.
Granite is less dense and rises higher, usually above land in continental crust.
Basalt is denser and so it will sink lower and form oceanic crust.
However, there is a layer of sediment on top of that crust. (sand, gravel, etc.)
