Lagoon

Atlantic Cross-Section Passive plate margins No active tectonic boundaries

Continental Shelf Slope: - leads into deeper water, steeper gradient - avg 370 ft/ mile - marks the true edge to a continent Rise: - slope merges into a more gradual incline - gradient of 20-40 ft/mile - rise may extend for a hundred miles or more into the deeper ocean - consists of sediment moved downslope from the shelf to the deep ocean - sediment delivered here by turbidity currents moving down the slope, which follow submarine canyons Shelf: - avg 50 miles wide and 425 ft deep - gradient of 1/10 of one degree (10 ft/mile) - shelves represent 7.5 % of the oceans area. - usually contain important mineral and petroleum deposits & fish. - evidence of sea level change - drilling & dredging has produced remains of animals abundant during the last ice age when sea levels were much lower. - usually consists of sediment washed off continent by rivers/streams

Active Margin Active tectonic boundary

Trenches Show us the location of subduction zones

MOR

Pillow Basalts

Black Smoker Diagram Entire ocean recycles every 6-8 million yrs!

Hydrothermal Sea Vents Bacteria oxidize H2S (ingest it) chemically. Independent of the sun. Chemical photosynthesis. Tube worms eat bacteria, clams, fish eat tube worms, etc. Unique ecological system on our planet -- doesn’t need the sun’s heat.

Europa Warm ocean

Volcanic Island

Island Pic

Volcanic Island Subsidence plus erosion; barrier reef continually builds and remains in the same place.

Barrier Reefs

Volcanic Island Island eventually erodes away leaving behind the reef, now called an Atoll.

Atolls

Wave

Wave Movement

Tsunami

Longshore Current

Longshore Pic

Beach Storm Response Summer: No storms. Steep beach. Winter: Storms interact with dunes, move sand offshore onto bars. Flat beach, wavecut dunes. Bars march back up to shore and dock onto beach over period of days or months, forming steep beach.

Barrier Islands

Barrier Island Pic

Tidal Channel

Baymouth Bar

Jetty

Groin Pic

Groin Pic

Groin Field

Prestorm

Poststorm

Seawall

Seawall Erosion

Seawall Erosion

Prereplenishment

Postreplenishment

1967 Development

1997 Development

Sea Level Rise

Sea Level Rise Pic

Western Headward Erosion

Wavecut Cliff

Sea Arch

Sea Stack

Wavecut Beach