Taxonomy term

plate tectonics

Small-scale factors influence mantle flow under the seafloor

In December 2011, scientists and technicians aboard the research vessel Marcus G. Langseth dropped several ocean-bottom seismometers into the deep Pacific more than 1,900 kilometers southeast of Hawaii to measure seismic activity and electrical conductivity to a depth of about 300 kilometers below the seafloor. Now, these measurements are providing new insights into how the mantle flows and deforms below the rigid tectonic plates that make up Earth’s surface.

22 Nov 2016

Why tectonic plates lurch forward when they break

When continents rift, they often do so slowly at first, but then they can suddenly speed up. Why they suddenly go faster instead of rifting at a steady pace has long eluded explanation. But in a new study, researchers suggest that the lithosphere perpetually thins as it rifts, and that after passing a threshold, it snaps like a rope under too much tension, causing plate motions to accelerate.

16 Nov 2016

Geomedia: Books: "Alfred Wegener": The definitive biography of a geoscience star

Today, Alfred Wegener’s name appears in almost every geology textbook. He is celebrated as the father of the continental drift hypothesis, the forerunner of plate tectonics. This recognition is rather recent — since about the early 1970s, when plate tectonics became a unifying theory to explain the origins of continents, oceans, mountains, volcanism and many other geologic processes. During his life, Wegener’s hypothesis was rejected by many geologists, more so in North America than in Europe. The dramatic change of his status from heretic to hero thus makes Wegener’s story even more fascinating, not only to earth scientists but to general readers as well.

22 Sep 2016

Peeling North American Plate causing East Coast earthquakes

On Aug. 23, 2011, a magnitude-5.8 earthquake struck near Mineral, Va., shaking the Piedmont region and damaging several historic buildings in Washington, D.C. The quake caught many people by surprise because the eastern U.S. lies in the interior of the North American Plate, more than 1,500 kilometers from the nearest plate boundary. In a new study, researchers peering beneath the southeastern portion of the North American Plate may have found an explanation for why parts of the region experience more quakes than expected.

31 Aug 2016

Mantle convection makes Earth's crust bob

From the earthquake-prone Himalayas and Andes to the volcanically active “Ring of Fire” around the Pacific, the boundaries of Earth’s tectonic plates are often sites of considerable geologic activity. In contrast, the interiors of tectonic plates have been thought to be relatively rigid and quiet.

18 Aug 2016

Lack of fungi did not lead to copious Carboniferous coal

The Carboniferous Period is famous for supplying Earth with an abundance of coal deposits. According to one hypothesis, the formation of all this coal is explained by a proposed 60-million-year gap, or lag, between the spread of the forests globally about 360 million years ago and the rise of wood-eating microbes and fungi that could break down tough plant matter. But a new study refutes this idea, instead attributing the Carboniferous’ copious coal to the consolidation of the supercontinent Pangea.

25 May 2016

Reading the ridges: Are climate and the seafloor connected?

New research suggests that midocean ridge volcanoes respond to variations in sea level, potentially leaving topographic records of past glaciations in the form of abyssal hills. But could those volcanoes also influence the climate cycles that drive sea-level changes?

25 Apr 2016

Down to Earth With: Tectonicist Eldridge Moores

When Eldridge Moores was 10 years old, his family lived in Crown King, Ariz., a tiny, remote mining settlement high in the rugged Yavapai Mountains northwest of Phoenix. Money was tight and his family rarely traveled, so Moores vividly remembers a holiday road trip to visit his father’s relatives near San Francisco. The Bay Area left a deep impression on Moores, and, at the end of the journey, upon reaching the first of four switchbacks on the narrow dirt track that led up to Crown King, Moores vehemently pronounced that he would do everything he could to get out of there.

15 Apr 2016

An absentee note for ancient blueschist: Lack of metamorphic rock does not date onset of plate tectonics

Plate tectonics is a defining characteristic of our 4.5-billion-year-old home planet, responsible for earthquakes, mountain building, and much of the evolution of the planet’s oceans and atmosphere. But when this formative process began is a mystery. Some researchers have pointed to the lack of blueschist — a type of metamorphic rock that only forms in tectonically driven subduction zones — in rocks older than 800 million years as a clue to when subduction began. But a new study rules this option out, offering a novel explanation for the rock’s absence in ancient rocks.

05 Apr 2016

The question of mantle plumes

The mantle plume hypothesis is the most widely held explanation for volcanism far from plate boundaries, like Hawaii and Yellowstone. But some researchers question whether mantle plumes even exist.

20 Dec 2015