Geology

In a way, you could be walking on water right now. Water is carried to the mantle by deep sea fault zones which penetrate the oceanic plate as it bends into the subduction zone. Subduction, where an oceanic tectonic plate is forced beneath another plate, causes large earthquakes such as the recent Tohoku earthquake, as well as many earthquakes that occur hundreds of kilometers below the Earth's surface. Over the age of the Earth, the Japan subduction zone alone could transport the equivalent of up to three and a half times the water of all the Earth's oceans to its mantle, according to a new…

Relic moss samples exposed by modern Arctic warming have been found to date as far back as 44,000 years ago, according to radiocarbon dating.  When the temperature rises on Baffin Island, in the Canadian high Arctic, ancient Polytrichum mosses, trapped beneath the ice for thousands of years, are exposed. The authors collected 365 samples of recently exposed biological material from 110 different locations, cutting a 1,000 kilometer long transect across Baffin Island. From their samples the authors obtained 145 viable measurements through radiocarbon dating. They found that most…

Seismic waves penetrating to a depth of almost 200 miles report the discovery of an anomaly that likely is the volcanic mantle plume of the Galapagos Islands - it's just not where geologists and computer modeling had assumed.  The Galapagos chain covers roughly 3,040 square miles of ocean and is centered about 575 miles west of Ecuador, which governs the islands. Galapagos volcanic activity has been difficult to understand because conventional wisdom and modeling say newer eruptions should be moving ahead of the plate, not unlike the long-migrating Yellowstone hotspot.  New…

Researchers have determined the isotope composition of the rare trace elements Hafnium and Neodymium in 2.7 billion year-old seawater using high purity chemical sediments from Temagami Banded Iron Formation (Canada) and concluded that large landmasses must have existed then. The Temagami Banded Iron Formation was formed 2.7 billion years ago during the Neoarchean period and can be used as an archive because the isotopic composition of many chemical elements such as Hafnium and Neodymium directly mirrors the composition of Neoarchean seawater. These two very rare elements allow many valuable…

The April 10th, 2013 landslide at a Utah copper mine probably was the biggest non-volcanic slide in North America's modern history, and included two rock avalanches that happened 90 minutes apart and surprisingly triggered 16 small earthquakes, according to findings published in GSA Today. The landslide moved at an average of almost 70 mph, reached estimated speeds of at least 100 mph and left a deposit so large it "would cover New York's Central Park with about 20 meters (66 feet) of debris," according to the researchers. While earthquakes regularly trigger landslides this is the first…

From the earliest days on record, earthquake lights - rare, luminous phenomena associated with some seismic events - have mystified people and intrigued geologists.  Earthquake lights appear before or during earthquakes, but rarely after, and include spheres of light floating through the air. Seconds before the 2009 L'Aquila, Italy earthquake struck, pedestrians saw 10-centimeter high flames of light flickering above the stone-paved Francesco Crispi Avenue in the town's historical city center. On Nov. 12, 1988, a bright purple-pink globe of light moved through the sky along the…

4 billion ago, during the Archean eon, Earth's mantle temperatures were significantly higher than they are today, according to recent numerical model calculations. A new paper from researchers at at Johannes Gutenberg University Mainz says the Archean crust that formed under these conditions was so dense that large portions of it were recycled back into the mantle. According to the calculations, this dense primary crust would have descended vertically in drip form. In contrast, the movements of today's tectonic plates involve largely lateral movements with oceanic lithosphere recycled in…

The Earth is about 4.6 billion years old but no rocks exist that are older than about 3.8 billion years. However, zircons that were eroded from the sedimentary rock section in the Jack Hills of western Australia, which more than 3 billion years old, were eroded from rocks as old as about 4.3 billion years. These Jack Hills zircons are the oldest recorded geological material on the planet. In 2007 and 2008, two research papers in Nature reported that a suite of zircons from the Jack Hills included diamonds, requiring a revision of early Earth history. The papers posited that the diamonds…

Most science fiction and news stories describe Mars terraforming as a long term but simple process. You warm up the planet first, with greenhouse gases, giant mirrors, impacting comets or some such. You land humans on the surface right away and they introduce lifeforms designed to live on Mars. Over a period of a thousand years or so, life spreads over the planet and transforms it, and Mars becomes a second Earth. However no-one has yet terraformed a planet. There are many theoretical reasons for supposing it wouldn't be as easy as that. What's more, this process if it goes wrong could lead…

The Promised Land means different things to different people. To geologists, the site of some of the largest volcanic eruptions in earth's history might fit the bill, and that means Utah is a pretty good place to be. 30 million years ago, more than 5,500 cubic kilometers of magma erupted during a one-week period near a place called Wah Wah Springs. By comparison, this eruption was about 5,000 times larger than the 1980 Mount St. Helens eruption. Fortunately they are no longer active. Dinosaurs were already extinct during this time period, but less well known is that 25-30 million years ago,…