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Lecture 7

Lecture 7


Department
Environmental Science
Course Code
EESA06H3
Professor
Nick Eyles
Lecture
7

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EESA06: LECTURE #7
Steep sided, pyroclastic volcano which arent in Iceland because there are basalt
volcanoes in Iceland therefore these volcanoes are in Ecuador
Went to Ecuador to the Galapagos Islands which are right on the equator and
islands in the middle of the ocean; they are a classic example of Hot Spots
The islands themselves are just the tip of an iceberg of a plateau that submerges to
the east
Nazca plates moving to the east and moving volcanoes away to the east and they
become eroded and create hot spot trails of old dead volcanoes that have flat tops
and are below sea level
Volcanoes that have become flat topped and are dead are called Guyouts
About 40 hot spots, most of them are on oceanic plates
Hot spots usually associated with hot spot islands in the middle of oceans
Wanted to know why do we get islands in the middle of oceans and found that the
age of the islands: the age of the rocks on the hot spot island are much younger
compared to the rocks on the oceanic floor, and the youngest island is right above the
hot spot and as you go down the trail you get extinct volcanoes and then eventually
they go below sea level
Systematic aging of the rocks as you move away from the hot spots and move down
the train
Orientation of the hot spot trail tells us the direction of plate movement
Hot spots played a key role in plate tectonic theory
All islands on Galapagos islands have shield volcanoes relatively not dangerous
Hot spots is composed of smaller spots
Bathymetric map is a map that shows water depth
Very fluid basalt coming out of shield volcano, bumps in the middle part which is
magma hitting water and are called phreato magmatic eruptions; water will go down
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and hit the magma and you get a violent release of steam and you get local
pyroclastic eruptions; very young landscape because there is no vegetation
Ropey lava= pahoehoe lava
An eroded remnant of a volcano is what happens to a volcanoe when it moves away
from a hot spot
Pyroclastic ash which are layers of ash thrown up into the air and falls onto the land
A cinder cone volcano which is ash being blown out and accumulating around the
cone and foreground which is layers of coarse ash being deposited near the volcano
and is called Scoria which are larger pieces of volcanic ash
Trace fossil was on the island which is the track of an organism (made by turtles)
Giant prickly cactus have that specific shape of being raised because predation (to
eat something) because they are being eaten my giant tortoises therefore the
cactuses have grown these long pointy stems and have become a lot taller
Blue footed booby have special beaks because they dive from a great height for fish
therefore its nostrils are right below its eyes so they could be a much more efficient
diver
Galapagos famous because of Charles Darwin who published in 1859 The Origin of
Species
He recognized volcanic activity and saw landscaped being changed which made him
realized that the Earth was evolving which was a background on his ideas for
biological evolution
The beaks of the finches were different because they lived on different diets; he made
collections of the bird but didnt note where hes got them from and 20 years later he
found out where he got it from and realized that what hed seen earlier is
adaptation, speciation, etc.
Some of the populations of the tortoises are gone on some islands because they were
used in the 19th century for sources of meat for ships and because their habitats were
destroyed because of urban development and livestock stripped their vegetation; also
there were rats and feral (wild) cats
Rocks and minerals are clues to ancient environments
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