THE GEOLOGY OF ICELAND IN THE CENOZOIC ERA

ABOUT ICELAND

Iceland sits astride the Mid-Atlantic Ridge. The MOR is part of the world-circling underwater mountain system where new crust is continuously created. The MOR is constantly enlargening the boundaries of Iceland. Iceland was formed by the spreading boundary of the North American and European plates and a hotspot or mantle plume. As these plates moved apart, continuous and excessive eruptions of lava constructed volcanoes and filled rift valleys. Continued movement rifted the lava fields and caused long, linear valleys bounded by parallel faults. These movements persist into the present, along with earthquakes, reactivation of old volcanoes and the creation of new ones.

Eleven percent of Iceland's surface is covered by glaciers, dominated by Ratnajokall, which is the largest glacial cap in Europe.

Average height above sea level is around 500km and the highest peak, Hvannadashnjukur, reaches 2,119m.

Formed from the sea by what were mostly volcanic forces, Iceland is the youngest country in the world.

Volcanic forces are still very active, with an eruption in progress somewhere in the country for one out of every five years in the past.

Due to the Mid-Atlantic Ridge and the continous outflow of lava it produces, Icelanders have been able to harness geothermal power from the spreading ridge and all of Iceland is now powered by it.

ABOUT THE CENOZOIC ERA

The Cenozoic Era extends from about 65 million years ago to the present.

65 ma: Maammals become abundant after the extinction of dinosaurs and large reptiles.

55 ma: Mammals become dominant and whales make their first appearance.

38 ma: Mammlas continue to populate the continents of the world and rhinoceroses and pigs make their first appearance.

26 ma: More modern mammals can be observed: horses, bears, dogs, modern whales, monkeys, modern birds, and apes.

7 ma: Mammals similar to modern form evolve.

1.8ma : Ice ages abound; Homospaiens evolve

0.01ma: Human history begins.

ICELAND IN THE CENOZOIC ERA

Like every other land mass on the Earth's surface, Iceland has not always been located in its present position. Following the formations and subsequent break-ups of Pangea, Iceland has migrated across the globe.

40,000,000 years ago much of Europe was submerged. Following a small land rise the contitnent emerged from the sea covered with lakes and bays. The Arctic Ocean was connected with the Mediterranenan Sea. The Atlantic and Pacific Oceans were separated. North America was connected to Asia by the Bering Strait Land Bridge and to Europe by way of Greenland and Iceland, which by this time has moved very close to where we can find it on a map today.

About 35,000,000 years ago is when placental mammals began to dominate. New species were being found in the land, water, and sky. Despite the amassing of land in high latitudes , the world climate remained relatively mild because of the enormous increase in the size of the tropic seas and because of the fact that the land was not elevated sufficiently enough to produce glaciers. Extensive lava flows began to occur in both Greenland and Iceland, which resulted in some coal being deposited between these layers.

Around 15,000,000 years ago unsettled conditions prevailed throughout the world. The straight of Gibralter closed, Spain was connected to Africa by an old land bridge, aand the Mediterranean Sea flowed into the Atlantic via a narrow channel which extended across France. The Iceland land bridge submerged at this time and the arctic waters began to comingle ith those of the Atlantic Ocean, thus rapidly cooling the Atlantic coast of North America and greatly affeting its ecosystems.

Starting less than 5,000,000 years ago the world became gripped by a cycle of numerous ice ages. During the Early Ice Age, North America and Eruope were highly elevated on an extensive scale, the ocean currents shifted, and the seasonal winds changed their direction. These conditions comingled to produce almost constant precipitation and snow began to fall on these elevated regions, thus cooling them down and attaining snow depths of almost 20,000 feet. The largest ice sheets of this period could all be found on eleveated highlands, rather than in the mountainous regions where we find them today. The nothernmost regions of the world have experienced six separate and distinct ice ages, although there are many numerous ice events associated with each of theses six ice ages. During this time, Greenland was covered by ice sheets and Iceland was completely buried beneath the ice flow.

During the Little Ice Age which occured between 1550 and 1920 in the Current Era, climate changes began to take place and there was glacier advancement in the Alps. In the years of 1300, 1600, and 1890 there was poor grass growth, animal and glacial advancement being obseved in Iceland. Sea Ice recods and accounts of fishermen attested to the various climate changes occuring in Icelans during this time.

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Iceland is a fascinating place geologically speaking due to many factors. It is a young country which has a multi-faceted identity. It consists of a vast array of geologic features and environments which continually inspires and facinates geologists. It is located on, and is thus part of, the Mid-Atlantic Ridge and therefore Iceland continues each year to increase in size, spreading at about the same rate at which human fingernails grow. Along with New Zealand it is one of the most conducive places in the world for harnessing and utilizing geothermal power, an ecologically sound way of generating electricity. Iceland is also one of the most geologically active places in the world and that is why it is continually being used as a labratory of geologists and geology students the world over.

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For those interested in finding out more concerning the information used in this site, here are some of the sites that I found to be useful:

http://www.pangaea.com/_iceland.html

http://geotech.civen.okstate.edu/magazine/geo-ceno.htm