marine biology revision

oceanography

Draw 7 major features of the sea floor and their characteristics.

A bathymetric feature is the shape of underwater terrain.

7 major bathymetric features are:

Continental margin - the region of transition from the land to the deep sea-floor between continental and oceanic crust. It consists of three different features: the continental rise, slope, and shelf.

Seamounts - are underwater mountains that rise from the ocean floor without reaching the water surface (sea level) and are typically cone shaped.

Volcanic Islands - is a large volcano that has erupted on the seafloor and has emerged above sea level and have rugged or mountainous interiors with a wide range of summit elevations.

Deep-sea trenches - any long, narrow, steep-sided depressions in the deepest prats of the ocean. They are formed by subduction, where two tectonic plates converge and pushes one plate beneath the other.

Mid-ocean ridges - a continuous range of underwater volcanoes that wraps around the globe. They usually occur along divergent plate boundaries, where new ocean floor is created as Earth's tectonic plates spread apart.

Atolls - a ring-shaped coral reef, island, or series of islets.

Ocean-basin floor including abyssal plains and hills - abyssal plains are not solely flat, but are punctuated by hills and seamounts.

Describe how mid ocean ridges form in relation to plate tectonics

Mid-ocean ridges occur along divergent plate boundaries, where new ocean floor is created as the Earth's tectonic plates spread apart (diverge) due to forces generated by rising magma.

Explain convection currents in the asthenosphere cause divergent plate boundaries

Convection currents generated within the asthenosphere push magma upward through volcanic vents and spreading centres to create new crust.

Why are trenches often found near subduction zones?

At many convergent plate boundaries, dense lithosphere melts or slides beneath less-dense lithosphere in a process called subduction, creating a trench.