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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