Transcript Earth Science

Coach Williams
Room 310B

Marine Environment

Objectives:
◦ Explain how shoreline features are formed and
modified by marine processes.
◦ Describe the major erosional and depositional
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


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


Where freshwater river/stream enters ocean
Freshwater & saltwater mix




Longshore bar: sand bar
Longshore current: current parallel to shore
Moves sediments
Rip currents: current out to sea through gap
in sand bar





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

Artificial structures
◦ Seawalls, groins, jetties, break-waters


Protect properties, beaches, etc…
Causes loss of sediments on beaches

Global warming: rise
◦ Melts ice
◦ Water expands

Plate tectonics
◦ Uplifts/sinking
◦ Emergent coasts: uplift of coasts

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.


Sonar/satellite imaging
Topography

Continental margin: submerged part of
continent
◦ Cont. Shelf
◦ Cont. Slope
◦ Cont. Rise





Shallowest part of continental margin
Average depth: 130m
Was covered by water after ice age
Fishing
Oil, natural gas



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






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)



Most of mountains on seafloor: extinct
volcanoes
Seamounts: submerged volcanoes higher
than 1km
Guyots: submerged volcanoes with flat tops






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)