Chapter 16

The Marine Environment

The Shore

• The shore is the area of land between the low tide and area affected by storm waves.

Erosional Shoreline Features

• Headlands are eroded by wave action to produce wave cut platforms

Longshore Currents

• Longshore currents move large amounts of sediments along the shore.

Depositional Shoreline Features

• Seashores are in a constant state of change. Sediments are moved and deposited by longshore currents

Human Impacts

• Humans modify the shoreline to try to control beach erosion

Use of groins to control erosion

Changes in Sea Level

• Climate change caused by global warming is causing sea levels to rise:– Thermal expansion: global temperature increases,

causing seawater to heat up and expand, leads to rising sea level

– Melting glaciers adds to ocean volume

• Tectonic forces (uplift and sinking) can affect sea level in local areas

Seafloor Features

• Continental margin: where continent meets ocean

Continental Margin

• Continental shelf: average depth 130 meters; width can vary from a few to hundreds of kilometers

• Continental slope: the true edge of the continent; deep submarine canyons

• Continental rise: the base of the continental slope

Deep-Ocean Basins

Deep-Ocean Basins

• Abyssal plains: flat parts of the ocean floor• Deep-sea trenches: deepest parts of the

ocean, created by ocean plates sliding under other plates

• Mid-ocean ridges: undersea mountain ranges, created by two plates being pushed apart

• Other features: seamounts, guyots, hydrothermal vents

Marine Sediments

• Terrigenous (deep-sea mud): originates on land

• Biogenous (oozes): forms from living organisms

• Hydrogenous: elements that precipitate directly from seawater. Ex: manganese nodules