Igneous Rocks and Processes and Iceland

Note how Iceland is the only terrestrial part of the Mid-Atlantic Ridge

Set on the boundary between to divergent plates, the mid-Atlantic ridge, lies Iceland. It is one of the most volcanically active places in the world and so, many people must be wondering why this little igneous island is called Iceland. It gets its name from the Vikings who tried to lure people away from the slightly more temperate island of Iceland to the colder and more hostile environment of Greenland. This may be one of those stories that isn’t true, but if it’s not, it should be. Iceland’s name is not its only claim to linguistic fame. It is also the source of the word geyser. The word geyser only refers to one of the natural phenomena in Iceland, but everywhere else in the world the term is applied to the natural phenomena itself. Iceland is home to a geyser which at one point in time was believed to be the sole geyser in the world, being discovered in the late 13^th century since Columbus was still only just discovering the American continent and Lewis and Clark had yet to be born and only the buffalo knew about Yellowstone. It became a huge tourist location for Europeans that would flock to Iceland to see the ‘Geysir.’ It would shoot water into the 80 meters into the air every few hours, but recently it has been every few years. The main geyser sits over a hot spot created by the magma flowing up through a plume created by the diverging plates. Today, the geyser has possibly gone dormant, though a recent 6.5 Richter scale earthquake almost brought it back to life. It’s neighbor geyser, Strokkur, is becoming increasingly more active as the small hot spot travels South, but only shoots water a mere 25-30 meters into the sky.

This video shows a clip of the Strokkur geyser erupting.

Torfajökull - A Subglacial Volcano

A good display of a delta probably caused by a subglacial volcanic eruption and its resulting flood.

Iceland is also home to a large ice field that covers many volcanoes that are still active today, eruption on average every five to ten years. These eruption are primarily basaltic in nature and can create huge lava deserts as a result of the cooling lava flows. While typically the kind of volcano that is the most common on the island would be classified as a shield volcano, most of them are formed from fissures that are created by the spreading plates. As the island cracks open because it is being pulled apart, the magma may flow up and erupt onto the surface. Eventually, the build up around it from older eruptions from fissures create a volcano. It also moves away from the center of the mid-Atlantic ridge, but the magma and hot spots continue to keep the volcano active.  Eruptions that take place underneath the ice sheet can cause serious threats for the civilized areas in Iceland due to the landslides, mudslides, and floods that are the result of the major melting of the ice due to lava flow. The lava melts the ice in gross quantities and the water comes racing down towards towns and has in the past killed several Icelanders. These sorts of eruptions also cause major plumes of ash to rise up into the air that can solidify into glassy masses in the engines of airplanes and therefore stop air traffic in Europe due to prevailing winds. 

The eruption of Eyjafjallajokull Volcano

When volcanoes are not covered by ice fields and they erupt, the more felsic, but still primarily mafic lava travels great distances, sometimes over 100 kilometers away from the original eruption site. This causes a huge threat to the people of Iceland as their towns are constantly in jeopardy due to this long reaching flow. During one such eruption, ocean water was poured over the encroaching lava flow to stop it from destroying an entire town. This technique of stopping the lava by forcing it to cool with water was highly controversial since it was a huge economic undertaking due to to the resources need to pump the water onto the lava had to be imported at high cost.  There is no truly safe place to live in Iceland since volcanism and seismic activity is always a constant threat due to the island’s location on the rift. 

A home leftover from the  Vestmannaeyjar eruption in 1973.

Geothermal power plant in Iceland

Beautiful Black Falls

While volcanoes pose a threat to everyday existence in Iceland, they also give the people the greatest benefit. Since two new types of tourism, adventure and geotourism, are on the rise, Iceland has become a popular destination for thrill seekers and geologists, professional and amateur alike. These new touristic trends bring income to the island. Iceland is also known for its primary exports of ferrosilicon and aluminum. Silicon is abundant in felsic magmas. They also provide free geothermal heat due to the power plants that they use to heat water and then send it through the cities’ pipes. Geothermal energy is also very abundant and affordable. 

Sedimentary Rocks

This formation in Morocco was formed by uplifted sandstone and limestone. It shows the Atlas mountains, one of the five mountain ranges located in Morocco. The Atlas mountains are rich in minerals, but also in ores. 

Coal, salt, mercury, and phosphate can all be found here and are mined for the precious materials. 

The picture above shows the Anti-Atlas mountains. These are very similar to the Atlas mountains, but located much farther south east. They are also composed of mainly sandstone and are at a lower elevation than the Atlas mountains.

In this last picture, the Moyen Mountains can be seen. Overall, they are a smaller mountain range, but are steeper in some places rather than the Atlas mountains.

Metamorphic Rock

Metamorphic Rock is a type of rock resulting from large amounts of heat and pressure. This type of heat and pressure cannot be found on the surface of the Earth. The formation of metamorphic rock will only be found beneath the surface of the Earth.

Metamorphic characteristics are unique to those of the sedimentary and igneous rocks. Cleavage is unique to metamorphic rocks. Cleavage is a result of low amounts of temperature, that develops into a planar fabrick along which the rock will break. This is not a fracture but a type of structural discontuinuity in the rock.

Foliation is a unique characteristic to metamorphic rock aswell. Foliation is formed from differential stress and is expressed in many ways. Foliation can be the allignment of particles in a parallel orientation, or in light-dark banding, the flattening of mineral grains, or by the flattening of shapes from larger grained particles.

Light-Dark Banded Foliation



Flattening of Minerals and Rocks


Another characteristic unique to metamorphic rock is lineation, this is the allignment of minerals or allignment of deformed pebbles.

Metamorphic rocks come from the deformation and metamorphism of both sedimentary and igneous rocks.  Sedimentary rocks that undergo metamorphism such as shale will produce phyllite, schist, and gneiss. Sandstone will metamorphose into quartzite, and limestone will be changed into marble.

Igneous rocks that undergo metamorphism can form common metamorphic rocks like greenstone, greenschist, metarhyolite, deformed granite, gneiss and schist.

There are many different places around our world where metamorphic rock can be found. The Canadian Belt is the first. This large concentration of metamorphic rock flows from the Northern Atlantic to the Great Lakes and then finally up to the Artic Ocean. It is rich in Copper and Iron, two very useful resources to our society today.

This location of metamorphic rock makes for a very secluded lifestyle. Very cold seasonal temps will be dominate over most seasons.

Another Place to find metamorphic rock in the United States includes that of the eastern Side of the Appalacians.

It was in this area where there were abundances of copper and iron as well. 

The next area includes the large section of Mountains on the western side of the United States. These numerous mountain ranges have yealded very diverse metal minerals. Gold and Silver have been located in isolated areas, and then many different other metal minerals such as: copper,zinc, molybdenum, manganese, tungsten, chromite and uranium. Some of these minerals are found in decent amounts while others are not enough to allow for the United states to be self-sufficient in the metal mineral that they use.