18. Hawaii

Entering statehood in 1959, Hawaii remains the newest addition to the United States. The state comprises of 8 main islands; Hawaii, Maui, Kahoolawe, Lanai, Molokai, Oahu, Kauai, and Niihau. These are just a few of the hundreds of islands that make up the Hawaiian Island Chain.

All of the Hawaiian islands were created by plume volcanoes. A plume volcano is created as the core of the earth burns a hole in a tectonic plate, releasing hot magma. As the Pacific tectonic plate continues to move, the islands grow in a giant arc, which reveals the movement of the plate. Hawaii (or the "Big Island") is the newest and largest of the chain. Mauna Kea stands 13,784 feet above sea level (and 18,000 feet below sea level). If you count its hight from the sea floor, Mauna Kea has a total hight of 32,000 feet (3,000 feet higher than Mount Everest (1).

On a clear day in downtown Portland, it is evident the relationship this city shares with the Aloha state. Mt. Hood stands only 62 miles from Portland's city center. Mt. Hood is a giant stratovolcano that reaches 11,249 feet above sea level (2). Out of the dozens of large volcanoes in Oregon, Mt. Hood is considered the most likely to erupt in the near future. Unlike the Hawaiian Islands, the volcanoes of the Cascades are formed by subduction of the Juan de Fuca plate under the North American plate. As the oceanic plate is subducted, it melts away and reaches the surface, forming volcanoes.

Here is a short video that helps visualize this process. http://www.youtube.com/watch?v=NbDqJy28hBw

1. Stephen S. Birdsall. Regional Landscapes of the United States and Canada
2. http://en.wikipedia.org/wiki/Mount_Hood