Flashcards in Hot Spot Theory Deck (23):
Who came up with the hot spot theory?
J. Tuzo Wilson in 1963.
A Canadian geophysicist .
Name the observation Wilson noted?
In certain locations around the world volcanism has been active for very long periods of time.
Because volcanism was occurring all around the world for a very long time what did Wilson conclude?
There must be relatively small, long-lasting and exceptionally hot regions called hot spots.
These existed below the plates and provided localised sources of high heat energy to sustain volcanism.
Name a place which has several volcanoes?
What did Wilson hypothesise about the Hawaiian Island?
That the distinctive linear shape of the Hawaiian Island- Emperor Seamounts chain resulted from the Pacific Plate moving over a deep, stationery hotspot in the mantle, located beneath the present-day position of Hawaii.
What did the heat from the hotspot produce?
A persistent source of magma by partly melting the overriding Pacific Plate. The lighter magma (compared to surrounding solid rock) rises through mantle and crust to erupt onto seafloor forming an active seamount.
Over time, what does the countless eruptions cause?
A seamount to grow and emerge above sea level to form an island volcano.
What did Wilson suggest about the continuing plate movement
The movement eventually carries the island beyond the hotspot, cutting it off from the magma source and volcanism ceases.
What happens when one island volcano becomes extinct?
Another one develops over the hotspot.
The cycle is then repeated.
Volcano growth and death over millions of years has left a long trail of volcanic islands/seamounts across te pacific floor.
According to Wilson's hotspot theory what is happening to the volcanoes in Hawaii?
The chain should progressively get older and become more eroded the farther they travel beyond the hotspot.
How old is the oldest rock in Hawaii?
5.5 million years old is rock Kauai the north western most inhabited Hawaiian island.
In Hawaii how old are the oldest exposed rocks?
Less than 0.7 million years old.
In Hawaii where is the youngest rock located?
To the southeast it was initially suspected by the ancient Hawaiians long before any scientific studies.
What did the ancient Hawaiians notice during their voyages?
They noticed the differences in erosion, soil formation and vegetation making rocks north west the oldest. This idea was handed down to generations in the legends of Pele.
Who was Pele?
The fiery Goddess of Volcanoes.
How many hotspots have been active?
Over a 100 hotspots beneath the Earth's crust during the past 10 million years.
Where do hotspots occur?
Under plate interiors - African Plate.
Diverging plate boundaries.
Mid-oceanic ridge - Iceland, Galapagos Islands.
Name a hotspot underneath the North American Plate?
Yellowstone National Park in north west Wyoming, located under the continental crust.
How was Yellowstone produced?
The calderas were produced by 3 gigantic eruptions during the past 2 million years (most recent one was 600,000 years ago)
How far do ash deposits go away from Yellowstone during an eruption?
As far as Iowa, Missouri, Texas and northern mexico.
The thermal energy of Yellowstone can fuel what?
More than 10,000 hot pools and springs, geysers and bubbling mudpots.
Because a large body of magma capped by hydro thermal system exists beneath the caldera.
Hydro thermal system.
Zone of pressurised steam and hot water.