Iceland is one of the most recently formed places on earth. That is because it is so volcanically active. Steaming lava fields are common. So are inactive lava fields, glaciers, hot pools, and geysers. This makes Iceland unforgettable. Much of that elemental handiwork is the result of the awesome power of volcanoes and tectonic plates.
What really astounded me is how Iceland makes visible for all to see, how tectonic plates operate. The earth’s surface comprises a number of massive plates. There are thought to be 7 major plates and many more minor plates. Those tectonic plates are not static. Instead those tectonic plates float on the mass of superheated magma beneath them. These plates, for example, have caused the earth’s crust in many places to form huge mountain ranges. The earth is not inert. It is a living moving thing.
Nick Eyles and Andrew Miall have described these plates very poetically:
We now know that planet Earth is a giant engine fuelled by the heat generated by the radioactive decay of uranium, thorium, and potassium in its interior. In effect, Earth is a giant nuclear reactor. We live on its thin wet and brittle crust that is broken into rigid plates like panels on a soccer ball. These plates move over the Earth’s surface atop giant convection currents stirring deep within the mantle. Carrying continents as passengers, these migrating plates crate a dynamic, always changing jigsaw puzzle as one plate interacts with its neighbours. The term plate tectonics refers to the creation of new plates and inexorable destruction of old ones. .
Scientists are still trying to unravel the history of how the continents have moved, but what we have learned so far is mind-boggling. Newfoundland and Northern Africa used to be locked together.
Tectonic plates move, but they don’t move fast. They move at about the speed of 2 cm (0.75 inches) per year which is about the speed that your fingernails grow.
The history of how the science of plate tectonics developed is deeply fascinating. As Eyles and Miall explained,
“The concentration of radioactive elements in the mantle (such as uranium, thorium, and potassium) is very small but the mantle’s volume is so large that even after 4.5 billion years, more than 10 trillion Watts of power continues to be produced radioactive decay every second! Cooling of the Earth’s surface and heating of the interior forces motion in the mantle—a process known as mantle convection—where enormous slabs of cool dense rock sink deep into he planet below subduction zones. In addition to its own radioactive heating, the mantle is warmed by trillions of Watts of heat released from its underlying core. The core’s own heat produces 200-kilometre thick hot layer at the base of the mantle …. Gigantic columns of hot buoyant material known as plumes, rise from this layer and slowly creep upwards towards the surface. Diamonds ejected to the Earth’s surface through kimberlite pipes originate in this layer.
Convection of the Earth’s deep interior drives the relentless motion of tectonic plate of the Earth’s crust. Despite its long history, the Earth has an enormous reserve of heat yet to be realized: consequently, the process of mantle convection, and thus plate tectonics will continue for billions of years to come”.
Most geological activity around the world is concentrated along boundaries between plates as, for example, the famous Pacific Rim. This is caused by the dynamic interaction of one plate with an adjacent plate or plates.
Volcanoes and earthquakes are symptoms of these moving plates colliding with each other at the place where tectonic plates meet such as the Pacific Rim. The boundaries of the plates can be convergentor divergent. Where the plates move together they are called convergent plates. Where the plates move apart they are referred to as divergent plates. Where plates are divergent they tear apart and then magma rises to the surface of the earth at that place. As a result this magma forms a new crust of the Earth. Where the edge of one plate the edge of one plate is forced underneath another plate mountains can rise up.
Iceland straddles a divergent boundarycalled the Mid-Atlantic Ridge where the Eurasian and North American tectonic plates are being pulled apart. We saw that clearly in Pingvellir where a UNESCO world heritage site has been declared as a result of that and its unique contribution to world culture (the world’s first parliament). It was astounding to see. According to our guide AO this and Africa are the only two places on the planet where this can actually be seen as clearly as this.
Pingvellir is the place where the two halves of Iceland and a good part of the part world, are breaking apart. The Eurasian and North American tectonic plates tear apart right here.
The Mid-Atlantic Ridge actually runs right across the island from the southwest to the northeast. I believe that some day, as a result Iceland will be split apart. This ridge is marked by a belt of volcanic craters, hot springs, steam springs, solfatars (areas of high temperature activity) and earthquakes. Frankly it always felt as if a volcano would erupt at any moment or an earthquake would make its presence felt. This belt is about 40 km (25 miles) wide in the north and up to 60 km. (40 miles) across the south. About 25% of Iceland is covered by this belt. It is everywhere.
The lava plain of Pingvellir is covered in wild flowers in the summer and we were very pleased to enjoy and photograph those flowers. We actually walked right through the place where the world seems to be splitting apart! As Insight Guide to Icelandputs it,
This is also a spot where the two halves of Iceland—the Eurasian and North American tectonic plates—are tearing apart. Aerial photographs show that the great crack of Almannagjá (everyman’s chasm) on whose flanks the Alpingi was held, is just one fissure in a huge series running north east like an ancient wound through the plains. Occasional earthquakes have reshaped the site: a quake in 1789 caused the plain to drop about 1 metre (3ft.).
As part of this process they created a commonwealth Alpingi in 930. This was the first Parliament in the world and the Icelanders are justifiably proud of it
Nick Eyles and Andrew Miall, Canada Rocks, (2007) p. 23
Nick Eyles and Andrew Miall, Canada Rocks, (2007) p. 27