Volcanoes

As the Pacific Plate slides under the North American Plate, it begins to melt from the heat generated in the earth's interior.  This molten rock (magma) rises through the North American Plate until it reaches the surface and erupts in volcanoes.  It is this process that has created the Aleutian Volcanoes.  Over millions of years, the lava from these volcanoes made the land of the Aleutian Islands and the Alaska Peninsula.  

The map below really illustrates this.  Notice how the Aleutian Islands and the Aleutian volcanoes occur 100 to 200 miles past where the Pacific Plate starts to go under the North American Plate at the Aleutian Trench.  This is where the diving Pacific Plate rock melts and then rises up to make volcanoes and the land of the Alaska Peninsula and the Aleutian Islands.

Next Page