Taxonomy term

plate tectonics

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

Did crustal chemistry buoy Western Plains?

The mighty mountains of the American West may captivate artists and adventurers with their rugged allure, but it’s the humble High Plains that intrigue certain geologists. For decades, scientists have puzzled over the origins of this vast plateau, which stretches for more than 500 kilometers east of the Rockies.
 
12 Jul 2015

Down to Earth With: Geophysicist Peter Molnar

As a graduate student in geophysics at Columbia University in the late 1960s, Peter Molnar — who had studied physics as an undergraduate — decided to sit in on a geology course for a term. When the professor began discussing cratons one day, Molnar raised his hand and asked what a craton was. Molnar still remembers the strange look he received, as if the professor were wondering, “Who let this guy in?”
 
20 Jun 2015

Getting to the bottom of a tectonic plate

Earth’s rigid, brittle lithosphere is broken into seven major plates, as well as many minor plates, which ride along atop a ductile layer of the upper mantle called the asthenosphere. For all we know about Earth’s cracked outer shell, however, a clear picture of the lithosphere-asthenosphere boundary at the bottom of the plates has proved elusive. Now, new research using explosives to image the oceanic plate dipping beneath New Zealand’s North Island is helping to blast away some of the uncertainty about this boundary by giving scientists a sharper look at a piece of the planet’s tectonic underbelly.

08 Jun 2015

Did a geographic shift trigger the Cambrian Explosion?

Roughly 530 million years ago, Earth’s living cast of characters ballooned as a surge of evolutionary development led to the sudden appearance of almost all modern animal groups. Fossils from this period document the change in species, but the geologic, atmospheric and/or biotic factors that may have caused the radiation remain mysterious. Now, a new study suggests that massive changes in the positions of the continents may have played a significant role in sparking the Cambrian Explosion.

27 Mar 2015

Thank subduction for Earth's nitrogen-rich air

Plate tectonics underlies many of Earth’s distinctive features, from its ever-shifting continents to its colliding mountain ranges and continuously forming crust at mid-ocean ridges. According to a new study, the process might also explain another of our planet’s peculiarities: its nitrogen-rich atmosphere.

 
08 Mar 2015

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