Geology is the study of the Earth. This scientific study includes how the Earth was formed, how the Earth has changed since it was formed, that materials that make up the earth, and understanding the processes that act on it. Marine Geology focuses these studies in areas affected by our oceans. These are the deep ocean floor, the shallower slopes and shelves that surround the continents, and especially the coasts which include beaches, estuaries, rivers, and large lakes.
We study rocks to learn about the materials that make up our Earth. The distribution and properties of these rocks give clues as to how they got there and the processes involved. Why study these things? The materials that we take out of the earth (oil, gas, metals, and other minerals) are vital to our way of life. Understanding where and how much of these resources we have is important in planning our future. Earthquakes, volcanoes, landslides, and hurricanes affect many of us at any moment. Understanding these processes will help to prepare for these events.
Learn more about Marine Geology at http://walrus.wr.usgs.gov/pubinfo/margeol.html