Volcanic Islands and Coral Atolls: Hawaiian Islands, Hotspot Theory, and Coral Formation, Slides of Biology

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Over 100 volcanoes in a volcanic island arc system

Big Island

Meiji (3000 m deep)

Bathymetric Profile of Hawaiian Emperor Chain

J. Tuzo Wilson (1963), a Canadian geophysicist ,came up the " hotspot " theory. (^) volcanoes of the Hawaiian chain should get progressively older and become more eroded the farther they travel beyond the hotspot.

Much of the Hawaiian island arc is underwater and extends toward Midway

Moves in a northwesterly direction

WE’VE GOT HOT SPOTS ALL OVER THE PLACE

OTHER ExAmPLES Of HOT SPOTS inCLudE:

CAPE VERdE (Off THE COAST Of SEnEGAL), GALAPAGOS iSLAndS (Off THE COAST Of EquATOR), SOCiETy iSLAndS (fREnCH POLynESiA), TRiSTAn dA CunHA (SOuTHERn ATLAnTiC), yELLOWSTOnE, ETHiOPiA PLATEAu, LORd HOW (nEAR SydnEy), iCELAnd, And mAny mORE.

Aging islands and coral:

• Drilling and removing core sample
• C 14 dating

Barrier Reef- separated from land by a lagoon

Fringing Reef- boarders coastline closely

Island subsides

Atoll- coral ring with central lagoon

lagoon is a shallow area with a sandy floor, patch reefs, and patches of seagrass

Darwin’s Theory of Coral Atoll Formation: Subsidence Theory

Fringing Reef- Tahiti

Barrier Reef Profile

Australia- Great Barrier Reef

Reef Flat of a Barrier ReefReef Flat of a barrier reef

Reef Flat

Coral Island

(Cay or Motu)

Reef Front

Lagoon

Open Ocean

Cross Section

of an Atoll