The processes which create the rich diversity of life found in Stellwagen Bank National Marine Sanctuary are varied and complex. Geologic processes over thousands of years have shaped the bank and surrounding basin which affect water currents and create habitat at the bottom of the ocean. Upwelling caused by the geology of the bank mixes nutrient rich water from deeper depths with warmer sun-lit water near the surface nourishing plankton at the base of the food web. Benthic and pelagic marine organisms feed on phytoplankton and zooplankton forming the backbone of myriad ecosystems. The following chapters: Geology, Physical Oceanography and Ecology, explain some of these processes in the context of Stellwagen national Marine Sanctuary.