Taxonomy term

early earth

Meteorite impacts may have kick-started ancient subduction

Earth in the Hadean Eon, between 4.56 billion and 4 billion years ago, was much too hot to support active plate tectonics as we know it today, where cold, established plates slowly march around Earth. Yet some evidence, including from tiny zircon crystals dating to the Hadean, has suggested that a form of plate tectonics was active by about 4.1 billion years ago — about a billion years before many researchers think modern plate tectonics started. The mechanisms that could have initiated and sustained early tectonics are unclear, but according to a new study, constant bombardment of early Earth by meteorites could have triggered temporary bursts of early tectonism.

22 Feb 2018

Small warm ponds: Ideal incubators for first life?

The first embers of life are thought to have emerged on Earth between 4.5 billion and 3.7 billion years ago, but how and where the initial sparks arose remains a mystery. Two leading theories suggest that the first self-replicating molecules — a necessity for life — may have gotten a start either in deep-ocean hydrothermal vents or in small warm ponds on land. In a new study, researchers suggest that the wet-dry cycles occurring in small, seasonal ponds would have made a better natural incubator.

17 Jan 2018

Young Costa Rican lavas might reflect pockets of primordial mantle

During the Archean, between 4 billion and 2.5 billion years ago, Earth’s super-heated young mantle produced a unique type of lava known as komatiite. In a new study published in Nature Geoscience, researchers looking at 90-million-year-old komatiites in Costa Rica — by far the youngest komatiites ever found — suggest the modern mantle may still harbor pockets of intense heat reminiscent of early Earth.

18 Aug 2017

When and how did plate tectonics begin on Earth?

Earth’s surface is a shifting puzzle of plates that collide and diverge, generating earthquakes, fueling volcanoes, opening ocean basins and raising mountain ranges. But when and how did this process — unique in our solar system as far as we know — begin? 
22 May 2017

Life on land 300 million years earlier than thought

Life emerged on land about 300 million years earlier than previously thought, according to a new study in Geology by scientists who discovered minerals in 3.22-billion-year-old rocks that they suggest could only have formed with the help of biological processes.

13 Mar 2017

Liverworts, not moss, dominated Earth's early terrestrial ecosystems

Moss, the springy green plant that blankets forest floors, has been heralded as the generator of large amounts of oxygen to Earth’s atmosphere during the Paleozoic. In a new study, however, researchers suggest that it could have been the overlooked relative of moss — liverworts — that dominated early terrestrial ecosystems and thus had more to do with reducing high carbon dioxide levels in the atmosphere at the time and cooling climate globally.

 
08 Feb 2017

Comment: Did life start on a snowball?

Somewhere toward the end of the Hadean, life emerged on Earth. Conventional wisdom suggests the Hadean was a hothouse, but what if instead it were a global icehouse? Could life still have emerged?

06 Oct 2016

Zircons hold clues to early Earth

Not much is known about the first 500 million years of Earth’s history, between 4.5 billion and 4 billion years ago. We know the interior of the planet was hotter than it is today, and that Earth’s surface experienced intense meteorite bombardment, which left the surface pocked with magma-filled craters. But with no rock record available from this period — the oldest rocks are 4.04 billion years old — scientists must look to the composition of tiny grains of the mineral zircon to provide clues about Earth during the Hadean Eon. But where did the zircons come from?

09 Sep 2016

Searching for the ancestors of meandering rivers

It might be difficult to imagine Earth devoid of vegetation, but for billions of years the sun shone, winds blew and rivers flowed on a planet without any plants.

21 Jun 2016

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