Earth ScienceCoach Williams

Room 310B

Marine Environment

Chapter 16

Objectives:◦ Explain how shoreline features are formed and

modified by marine processes.◦ Describe the major erosional and depositional

shoreline features.

Section 16.1 Shoreline Features

Headlands: land that sticks out into ocean Wave refraction: shallow water causes

waves to bend Beaches: eroded headland materials Erosion causes:

◦ Cliffs, sea-stacks/arches, platforms, sea caves

Erosional Landforms

Erosional Landforms

Sloping band of sand, pebbles, gravel, mud at the edge of the sea

Erosion & sediments◦ Rocky coast = pebbles◦ Volcanic rock (Hawaii) = black sand◦ Corals/seashells = white sand

Beaches

Beaches

Where freshwater river/stream enters ocean Freshwater & saltwater mix

Estuaries

Longshore bar: sand bar Longshore current: current parallel to shore Moves sediments Rip currents: current out to sea through gap

in sand bar

Longshore Currents

Rip Current

Erosion/sediments causes change Spits: narrow sand that sticks out in water Barrier Island: long ridges of sand apart

from the mainland Lagoon: body of water behind barrier

islands Tombolo: strip of sand that connects

mainland and island

Depositional Features

Spit

Barrier Island

Lagoon

Tombolo

Artificial structures◦ Seawalls, groins, jetties, break-waters

Protect properties, beaches, etc… Causes loss of sediments on beaches

Protective Structures

Protective Structures

Global warming: rise◦ Melts ice◦ Water expands

Plate tectonics◦ Uplifts/sinking◦ Emergent coasts: uplift of coasts

Changes in Sea Level

Objectives:◦ Explain the reason for the existence of

continents and ocean basins.◦ Compare the major geologic features of

continental margins and ocean basins.◦ Describe the different types of marine sediments

and their origin.

Section 16.2 The Seafloor

Sonar/satellite imaging Topography

Seafloor

Continental margin: submerged part of continent ◦ Cont. Shelf◦ Cont. Slope◦ Cont. Rise

Oceanic/Continental Crust

Continental Margin

Shallowest part of continental margin Average depth: 130m Was covered by water after ice age Fishing Oil, natural gas

Continental Shelves

Sloping region beyond shelf True edge of continent Turbidity currents: currents along bottom of

sea.◦ Fast moving; lots of sediment◦ Cut canyons along slope

Cont. rise: slope of deposits at base of slope

Continental Slopes

Deeper parts of ocean floor 60% of Earth’s surface Abyssal plains: smooth parts of basin Deep-Sea trenches: long depressions on

basin Mid-Ocean ridges: chains of underwater

mountains on ocean basin (volcanoes) Hydrothermal vents: hole in the seafloor

where heated fluids erupt (magma)

Ocean Basins

Abyssal Plain

Deep-Sea Trenches

Mid-Ocean Ridge

Hydrothermal Vents

Most of mountains on seafloor: extinct volcanoes

Seamounts: submerged volcanoes higher than 1km

Guyots: submerged volcanoes with flat tops

Seafloor Volcanoes

Most are from land Mud/sand by rivers Dust/volcanic ash by wind Ocean currents Ooze: sediments from once-living organisms Manganese nodules: sediment from

valuable metals (looks like potatoes)

Marine Sediments