023-Hawaiian Island Geology.ppt
Transcript of 023-Hawaiian Island Geology.ppt
Over 100 volcanoes in a volcanic island arc system
Big Island
Meiji(3000 m deep)
Hawaiian IslandsHawaiian Islands
Hawaii
Oahu
Kauai
Lanai Maui
Molokai
Niihau
Bathymetric Profile of Hawaiian Emperor Chain
Hawaii
(youngest)MauiOahuKauai(oldest)Pacific Plate
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.
Age of Hawaiian Islands
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 PLACEOther 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.
Older islands erode and subside
Aging islands and coral:• Drilling and removing core sample• C14 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
Fringing Reef
Reef Flat
Reef Front
Shoreline
Barrier Reef Profile
reefslope
reeffront
outerreef flatlagoonpatch
reef
islandinnerreef flat
Australia- Great Barrier Reef
Kaneohe Bay
Barrier Reef
Fringing Reef Patch 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
Atoll
Belize- Blue Hole
Kure Atoll (28° 25' N - 178° 20' W)Midway Atoll
Pearl & Hermes Atoll