Geysir: The Namesake of All Geysers

Geysers are rather amazing things: literal jets of hot, pressurised water that shoot from the ground, often dozens of metres into the air. To form these erupting hot springs, water has to travel through fissures to a depth of two kilometres below the surface and be warmed past the boiling point by a constant supply of…

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The Zanclean Flood: Refilling the Mediterranean

While the Mediterranean Sea is one of the cradles of ancient human civilisation, the water body is rather young geologically, approximately 5.33 million years old.  Researchers have found that this figure marks the date of the Zanclean flood, an epic breach of the Strait of Gibraltar that turned the desiccated Mediterranean basin into a sprawling…

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The Vajont Dam Disaster

Five decades ago, one of the deadliest dam breaches in history taught engineers a tragic lesson about constructing hydroelectric dams in geologically-unstable regions. At 261.6 m (862 ft) in height, the thin concrete arch Vajont Dam, on the Vajont River in the Italian region of Friuli-Venezia Giulia a few dozen metres above its border with…

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Eskers: Rivers of Rock

An esker in northern Manitoba.  Source: P. Camill, http://www.flickr.com/photos/pcamill/3475078644/.  Licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 2.0 Generic (CC BY-NC-ND 2.0) licence. The long, skinny, snake-like ridge you see in the above image is called an esker, its name derived from the Irish term for the formation, eiscir, referring to a long ridge.  If it looks…

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The Geography of the Geologic Time Scale

To follow along with the article, open the above image in a separate window or tab (936 x 1137).   Measuring time geologically is a complicated but very necessary task for properly determining the age of rock layers, fossils,   Many people are familiar with periods of geologic time such as Jurassic, Devonian, and Cambrian (or…

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Lōʻihi: The Next Hawaiian Island

975 m (3 199 ft) beneath the surface of the North Pacific Ocean, the next in the long chain of Hawaiian Islands is slowly brewing, awaiting the day in the future – anywhere between 10 000 and 100 000 years from now – when it bursts through the surface.  This is Loihi (Hawaiian Lōʻihi), currently a seamount…

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The Kola Superdeep Borehole and the Deepest Manmade Holes

The Mohorovičić discontinuity, or simply the Moho, is the transitional boundary between the crust of the Earth and the underlying mantle located 5-10 km (3-6 mi) beneath the ocean floor and 20-90 km (10-60 mi) beneath the surface of continents.  The Moho marks a transition from the basaltic rocks of the crust above it to…

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Curling Stones: A Precious Resource

Copyright: J. Durnan, http://www.geograph.org.uk/photo/988485.  Licensed for reuse under the Creative Commons Attribution-Share Alike 2.0 Generic licence. Ailsa Craig is the little white dot at the south end of the Firth of Clyde. Ailsa Craig.  A formidable, solitary, dome-shaped rock island lying in Scotland’s Firth of Clyde 16 km (10 mi) off the Ayrshire coast.  Uninhabited…

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Salar de Uyuni: The Flattest Place on Earth

Imagine an area 130 km (80 mi) long and 100 km (60 mi) wide – larger than 30 separate countries – that is blanched completely white and so flat that the variance in height from any single point to another is less than metre.  Such an area exists – the world’s largest salt flat, the…

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