During the early times, the ocean waters were filled with microscopic plankton, tiny plants and animals, which provided food for prehistoric fish and other creatures. As plankton sank to the sea floor, they were covered with sediment (sand and soil) and began to decay. Compressed under the weight of the water and sediments above, the decaying plankton was transformed into natural gas, filling the many cracks and fractures that naturally occurred in the shale rock.This is the Marcellus Shale. The Shale formation spans along six states including: Pennsylvania, New York, West Virginia, and Maryland in the United States. Russia, Iran & Qatar has large natural gas reserves too. It is important because of the natural gas reserve which could be extracted to supply the US for the next ten to twenty years.