Close window

This is a classification scheme for part of the Monterey Bay National Marine Sanctuary. While definitions may vary depending on the resource reference, the terms used in this figure are generally accepted. The intertidal zone is delineated by tidal fluctuations of sea level along the shoreline (i.e. the meeting of land and sea that is neither completely submerged nor exposed). The neritic zone includes the sea over the continental shelf, while the oceanic zone (or pelagic zone) overlies the continental slope and abyssal plains. Because sunlight attenuates as it penetrates water, the photic zone (sometimes called the euphotic zone) consists of the upper 100 m of water where photosynthesis is still possible. The aphotic zone lies below the photic zone; in some textbooks, a disphotic zone from 100 to 1000 m deep separates the euphotic and aphotic zones. The continental shelf is an underwater continuation of the continental land mass. The width of the shelf on the west coast of the US is much narrower than on the east coast. In general, the shelf is smooth, gently slopes seaward, and is not deeper than 120 m. At the continental slope, the bottom drops more steeply. This region may be riddled with submarine canyons that contain "rivers" of sediment that transport sediments, creating large fans at the base of the slope. Most of the deep ocean basin consists of flat areas called abyssal plains.

Close window