Stonehenge ‘altar’ carried on glacier

A massive slab at the center of Stonehenge somehow travelled 700 kilometres from its origin in northeast Scotland to its current home in the south of England. A model of Neolithic ice flows suggests a glacier might have carried the six-tonne monolith as far as Doggerland — an area that is now beneath the North Sea. Then, roughly 3,000 years before it came to Stonehenge, people may have saved the rock from rising sea levels. “What is exciting about these findings is that they could imply that the people of Doggerland attached cultural significance to the Altar Stone long before it was incorporated into Stonehenge,” says glaciologist and study co-author Remy Veness.

Ancient rocks point to an early start for the Great Unconformity

Fresh evidence from rocks in China is contributing to debate about what caused the ‘Great Unconformity’ — a one-billion-year gap in the geological record that exists all over the world. Theories abound: it might have been caused by abrasive worldwide glaciers during a period of ‘Snowball Earth’, or by erosion after the break-up of the supercontinent Rodinia. Tantalisingly, the period precedes a sudden proliferation of life on Earth, known as the Cambrian explosion. But new evidence suggests that most of the erosion that caused the gap happened long before all of that.

Oceans have never existed on Venus

Earth’s neighbour Venus has never had liquid water on its surface. One theory of the rocky planet’s history posited that after being covered by magma, the planet maintained a temperate climate for billions of years, which allowed oceans of water to form. Researchers used the chemical composition of volcanic gases in Venus’s atmosphere to infer the water content of its interior — a barometer of whether it ever had such oceans. They found only a 6% water content in the gases, suggesting a very dry planet that has never had liquid water on its surface.

First rocks returned from Moon’s far side reveal ancient volcanic activity

Two groups of researchers have taken the first-ever look at samples brought back from the Moon’s far side — and revealed a history of volcanic activity that spans billions of years. Nearly two kilograms of lunar soil was retrieved by the China National Space Administration mission Chang’e-6 and then dropped down to Earth in a re-entry capsule. Scientists found grains of dust in the sample that originated from lava that erupted to the surface as long as 4.2 billion years ago.

India’s pioneering mission bolsters idea that Moon’s surface was molten

The first-ever analysis of soil near the Moon’s south pole has found further evidence that the lunar surface melted shortly after it formed. The data come from India’s pioneering Chandrayaan-3 mission, which deployed a rover on the Moon last August that found the soil mainly comprised the mineral ferroan anorthosite. Previous landers have found similar results at other locations, suggesting the composition of the surface is uniform. This supports the theory that the Moon originated from material scattered into space when a large impactor struck the newly formed Earth.

Geology’s biggest mystery: when did plate tectonics start to reshape Earth?

Discovery of atmosphere on an Earth-like exoplanet

Investigations using the James Webb Space Telescope have confirmed that the exoplanet 55 Cancri e has a carbon-based atmosphere — the first time an atmosphere has been detected surrounding a rocky planet similar to Earth outside the Solar System. The planet orbits very close to its Sun-like star and can’t support life as we know it, in part because it is probably covered by a magma ocean.

The Solar System has a new ocean

Mimas, a small moon of Saturn, turns out to have an ocean beneath its icy surface — despite looking too geologically inert to have water sloshing inside. The fact that unexceptional Mimas has an ocean means that “you could have liquid water almost anywhere”, says astronomer Valéry Lainey. And that means a greater chance of extraterrestrial life somewhere: interactions between a buried ocean and a moon’s rocky core could generate enough chemical energy to sustain living organisms.

Strange blobs in Earth’s mantle are relics of a massive collision

Two mysterious blobs of rock in Earth’s mantle could be remnants of the planetary smash-up that formed the Moon. The formations sit in the layer between the crust and the core, are thousands of kilometres long and are slightly denser than their surroundings. Computer simulations suggest that they are from the protoplanet Theia, which smashed into Earth 4.5 billion years ago. Some of Theia’s remnants were flung into orbit, where they coalesced into the Moon.

Did dust from the Chicxulub asteroid impact kill the dinosaurs?

Dust might have been responsible for the deadly dinosaur-killing global winter that came after an asteroid slammed into Earth 66 million years ago. Climate simulations suggest that the impact kicked up enough fine particles to block out the Sun and prevent plants from photosynthesising for up to two years. The dust might have stayed in the atmosphere for some 15 years, which resulted in global temperatures dropping by as much as 15 ℃.

Two new minerals discovered in meteorite

Researchers have identified two, possibly even three, new minerals in a huge iron-based meteorite that landed in Somalia. The minerals have been named elaliite, after the meteorite’s location near the town of El Ali, and elkinstantonite after Lindy Elkins-Tanton, lead investigator of a NASA mission to a metal-rich asteroid. The 2-metre-wide meteorite has been well known to generations of people who live in the area, where it was named Nightfall.

Evidence of dinosaur-killing asteroid impact found on the moon

Researchers studying tiny glass beads in lunar soil samples brought back by China’s Chang’e-5 mission have reconstructed a timeline of asteroid strikes on the Moon — and found that they mirrored impacts on Earth. The finding suggests that asteroid strikes on our planet, including the one that killed the dinosaurs some 66 million years ago, were accompanied by a series of smaller collisions both here and on the Moon. This should make the history of Earth’s bombardment in some ways easier to study: the glass beads, formed by the heat and pressure generated during an asteroid strike, are common on the Moon but harder to find on Earth.

China’s Mars rover finds hints of catastrophic floods

China’s Zhurong rover has peered under the surface of Mars — down to 100 metres — and has found evidence of two huge floods that shaped the landscape. Since May last year, Zhurong has been exploring Utopia Planitia, in Mars’s northern hemisphere. Images from the rover’s ground-penetrating radar found layered patterns under the surface, which the authors suggest are made of sedimentary rocks carried in by two major floods around 3 billion and 1.6 billion years ago. But other scientists say that, although radar is good at detecting layers of subsurface material, it’s less proficient at identifying what layers are made of.

NASA’s Mars rover makes ‘fantastic’ find in search for past life

Since July, NASA’s Perseverance rover has drilled and collected four slim cores of sedimentary rock, formed in what was once a river delta on Mars. They are the first of this type of rock to be gathered on another world — and scientists are excited because at least two of the cores probably contain organic compounds, which, on Earth, are often associated with living things. If all goes well, the samples will be the first ever returned from Mars. They will be picked up by another spacecraft and brought back to Earth no earlier than 2033.

Milky Way spirals boost Earth crust formation

Earth’s crust builds up faster when the Solar System surfs through one of four spiral arms of the Milky Way. Researchers measured the decay of uranium in the ancient continental crust in Greenland and Australia to study how it formed between 2.8 and 3.8 billion years ago. They found that, every 200 million years or so — in tune with Earth passing through the Milky Way — the rate of crustal production increased. One explanation could be that denser areas of the galaxy dislodge more comets from the Oort cloud, which rain down on Earth, melting the crust and causing more magma to bubble up and congeal.

Diamond delivers long-sought mineral from the deep Earth

Small black specks in a diamond mined decades ago in Botswana have turned out to be a vital ingredient of the deep Earth. This is the first time the mineral has been identified in nature, after decades of searching.

Earth’s first continents emerged from the ocean 700m years earlier than thought

Earth’s first continents emerged from the ocean between 3.3 billion and 3.2 billion years ago, before the existence of plate tectonics. An analysis of rock sediments from India places the rise of the first stable continents some 700 million years earlier than previously thought. The rocks might have been formed by lava piling up from continuous volcanic activity on Earth’s crust, and floating above the water like an iceberg.

First peek inside Mars reveals a crust with cake-like layers

NASA’s InSight mission has finally peered inside Mars, marking the first time scientists have directly probed the inside of a planet other than Earth. Seismologists are using marsquakes to map the red planet’s interior, measuring differences in how seismic waves move through its structure to determine the make-up of the planet’s geological layers. The new data show that Mars’s crust is made up of either two or three layers. In the coming months, scientists will report on measurements taken even deeper, ultimately revealing information about the planet’s core and mantle.

Geologists uncover history of lost continent buried beneath Europe

Geologists have reconstructed, time slice by time slice, a nearly quarter-of-a-billion-year-long history of a vanished landmass that now lies submerged, not beneath an ocean somewhere, but largely below southern Europe. The only visible remnants of the continent—known as Greater Adria—are limestones and other rocks found in the mountain ranges of southern Europe. Scientists believe these rocks started out as marine sediments and were later scraped off the landmass’s surface and lifted up through the collision of tectonic plates. Yet the size, shape, and history of the original landmass—much of which lay beneath shallow tropical seas for millions of years—have been tough to reconstruct.

New map of Alaska’s ancient coast supports theory that America’s first people arrived by boat

New research supports an early sea arrival, by way of the Pacific coast. By dating rocks and animal bones, scientists conclude that the coast of southeastern Alaska was largely ice-free and full of plant and animal life some 17,000 years ago—a welcoming environment for people venturing south into a new world.