Karleskint Small Turner Chapter 3 Geology of the Ocean

Key Concepts The world ocean has four main basins: the Atlantic, Pacific, Indian, and Arctic. Life first evolved in the ocean. The earth’s crust is composed of moving plates, and the seafloor is always changing

Key Concepts The ocean floor has topographical features similar to those found on continents. The seafloor is composed of sediments derived from living as well as nonliving sources. Latitude and longitude determinations are particularly necessary for precisely locating positions in the open sea, where there are no features at the surface.

World Ocean Ocean and the origin of life –Stanley Miller’s apparatus –No oxygen (no photosynthesis!) in atmosphere ~ 4bya

World Ocean First cells were most likely anaerobic bacteria

World Ocean The ocean today: all “oceans” are connected!

World Ocean The ocean today –4 major ocean basins: Pacific (largest), Atlantic, Indian, Arctic –Sea: smaller than ocean, essentially landlocked –Gulf: large area of sea or ocean, partially enclosed by land –Strait or Channel: narrow body of water connecting 2 large areas of ocean –Bay, bight, fjord, inlet: open to 1 side only –Sound: open to 1 or both sides

Continental Drift Continents are always in (slow) motion New seafloor is produced at ocean ridges Old seafloor is removed at ocean trenches

Continental Drift Rift (Deep Sea Vent) Communities –specialized environments found at divergence zones of the ocean floor –primary producers are chemosynthetic bacteria Rift valley

Ocean Bottom Bathygraphic features –Geological features similar to land: mountain ranges; canyons, valleys; great expanses

Ocean Bottom Continental margins –continental shelf, continental slope, and shelf break

Ocean Bottom Ocean basin –abyssal plains and hills –seamounts –ridges and rises –trenches and island arcs

Ocean Bottom Life on the ocean floor –continental shelves are highly productive –life on the abyssal plains is not abundant, no sunlight, no photosynthesis

Composition of the Seafloor Sediment—loose particles of inorganic and organic material S&T!

Composition of the Seafloor Sediments –formed from seawater through a variety of chemical processes –formed from remains of living organisms: corals, shells of mollusks or planktonic organisms –produced from continental rocks by the actions of wind, water, freezing, thawing –from outer space

Biogenic sediments

Finding Your Way around the Sea Charts U.S. Gov’t

Finding Your Way around the Sea Reference lines: latitude & longitude

Finding Your Way around the Sea Navigating the ocean –Sextant to determine latitude with reference to Polaris –Chronometer to determine longitude by measuring time relative to Earth’s rotation NOAA Bjoertvedt

Finding Your Way around the Sea Navigating the ocean by Global Positioning System (GPS) NASA utilizes a system of satellites to determine position GPS measures the time needed to receive a signal from at least 3 satellites, and calculates position