The Hawaiian Islands formed over a stationary hot spot. This means that hot molten magma from deep within the mantle erupted onto the surface of the ocean floor, forming an underwater volcano, or seamount. As the volcano continued to grow, it eventually emerged above sea level, forming an island arc. The first island to form over the hot spot was Kauai Island. The island sits at the northernmost section along the chain, is now an extinct volcano, and contains the oldest rocks of the Hawaiian Islands. Maui is also an extinct volcano. It has much younger rocks than Kauai but older than the Big Island. Hawai'i is the southernmost island, has active volcanoes, and contains the youngest rocks of all the islands. By understanding that the Hawaiian Islands formed over a stationary hot spot, the youngest rocks are found on the actively-erupting Hawai'i island, and that rocks become progressively older as you move northwest helps support what theory?

The Hawaiian Islands are all formed as a result of volcanic activity of a hot spot. The hot spot is stationary, but the islands are in the shape of a chain, not all in the same place. Also, the rocks on the islands that do not have active volcanoes are older, than the ones that do have volcanic activity. This suggests that the Pacific plate is moving. According the direction in which the islands are arranged, the Pacific plate seems to move toward northwest. As it moves, it moves over the hot spot. Since the hot spot is stationary, as the Pacific plate moves, eventually the volcanic activity will stop on the island that has moved further away from the hot spot. On the other hand, new volcanic island will emerge from the sea over the hot spot. The process goes on for millions of years, and it can result in hundreds of islands of volcanic origin.