Geology Archives

October 8, 2023October 8, 2023 by Matt Williams

Is This a Collapsed Lava Tube on the Moon?

The spectacular sinuous landform shown above is thought to be a collapsed lava tube located near Gruithuisen K crater. Credit: NASA/GSFC/ASU

The Moon was once a geologically active place characterized by volcanoes, lava flows, and a magnetic field generated by action in its interior. The Moon’s airless environment has perfectly preserved evidence of this past and can be seen today as dark deposits, volcanic domes, and cones. But the most recognizable features are known as “sinuous rilles,” which are believed to be ancient lava tubes that have since collapsed. The Lunar Reconnaissance Orbiter Camera (LROC) recently captured images of a rille that extended 48 km long (30 mi) across the northern hemisphere.

September 9, 2023September 9, 2023 by Matt Williams

Every Night and Every Morning, the Moon Rumbles With Tiny Quakes

Artist's impression of astronauts on the lunar surface, as part of the Artemis Program. How will they store power on the Moon? 3D printed batteries could help. Credit: NASA

The Moon was geologically active between 3.7 and 2.5 billion years ago, experiencing quakes, volcanic eruptions, and outgassing. Thanks to the Moon being an airless body, evidence of this past has been carefully preserved in the form of extinct volcanoes, lava tubes, and other features. While the Moon has been geologically inert for billions of years, it still experiences small seismic events due to tidal flexing (because of Earth’s gravitational pull) and temperature variations. These latter events happen regularly and are known as “moonquakes.”

Thanks to the Apollo missions, scientists have measured this activity using seismometers placed on the surface. In a recent NASA-funded study, a team of researchers from the California Institute of Technology (Caltech) reexamined the seismic data with a machine-learning model. This revealed that moonquakes occur with precise regularity, coinciding with the Sun rising to its peak position in the sky and then slowly setting. In this respect, moonquakes are like a “Lunar Alarm Clock,” which could be useful for future missions and lunar settlers!

June 15, 2023June 15, 2023 by Evan Gough

Did Life Need Plate Tectonics to Emerge?

New research indicates that mobile plate tectonics—thought to be necessary for the creation of a habitable planet—was not occurring on Earth 3.9 billion years ago. Image Credit: University of Rochester illustration / Michael Osadciw

It’s widely accepted that Earth’s plate tectonics are a key factor in life’s emergence. Plate tectonics allows heat to move from the mantle to the crust and plays a critical role in cycling nutrients. They’re also a key part of the carbon cycle that moderates Earth’s temperature.

But new research suggests that there was no plate tectonic activity when life appeared sometime around 3.9 billion years ago. Does this have implications for our search for habitable worlds?

May 16, 2023May 17, 2023 by Matt Williams

The Moon has a Solid Core Like the Earth

A new study suggests that the moon's magnetic field from a dynamo in its liquid metallic core (inner red sphere) lasted 1 billion years longer than thought. (Image credit: Hernán Cañellas (provided by Benjamin Weiss))

Some fifty years ago, the Apollo Program sent the first astronauts to the Moon. In addition to the many science experiments they conducted on the surface, the Apollo astronauts brought back samples of lunar rock for analysis. The Soviet Luna program sent several robotic missions to the Moon around the same time that conducted sample-return missions. The examination of these rocks revealed a great deal about the composition of the Moon and led to new theories about the formation and evolution of the Earth-Moon system.

For example, analysis of the rocks revealed that the Earth and the Moon are similarly composed of silicate minerals and metals. This led to theories that the Moon’s interior is similarly divided into a silicate mantle and crust and a metallic core. However, many aspects of this theory, like the structure of the core (solid or molten?), have been debated for decades. According to new findings by a team of French scientists, it is now a scientific certainty that the Moon’s innermost region consists of a solid inner core surrounded by a molten outer core (just like Earth’s).

April 12, 2023April 12, 2023 by Carolyn Collins Petersen

Not Snowball Earth, More of a Slushball Earth

DNDXCB View of Earth 650 million years ago during the Marinoan glaciation. the idea of Slushball Earth may change how we view that past ice age. Credit: University of St. Andrews. — Artist's impression of Earth 650 million years ago during the Marinoan glaciation. Credit: University of St. Andrews.

Our planet hasn’t always been the warm, inviting place we know today. At least five times in its history, Earth froze over, locked in the grip of an ice age. Scientists sometimes refer to these periods as “Snowball Earth.” The popular idea is that everything was covered with ice, making life difficult, if not impossible. But, there’s new evidence that during at least one of these icy periods, parts of Earth’s surface could have been more like a giant mushy ball of slush.

April 11, 2023April 7, 2023 by Paul M. Sutter

The First Radiation Map of the Skies Over Africa

Inside this geometric structure is a demolished uranium mill and its radioactive tailings. Buried in 1992 by the Department of Energy, this mill near Grants, N.M. is one of about 20 uranium mill tailings sites in the U.S. that were remediated as part of the Uranium Mill Tailings Remedial Action project (UMTRA). Credit: U.S. Department of Energy

Astronomers have developed a way to cheaply and easily measure the radiation exposure experienced by airline crews over Africa.

March 5, 2023March 5, 2023 by Matt Williams

The Earth has an Even More Inner Core, and it's a Ball of Solid Metal

The Earth's layers, showing the Inner and Outer Core, the Mantle, and Crust. Credit: discovermagazine.com

For generations, scientists have probed the structure and composition of the planet using seismic wave studies. This consists of measuring shock waves caused by Earthquakes as they penetrate and pass through the Earth’s core region. By noting differences in speed (a process known as anisotropy), scientists can determine which regions are denser than others. These studies have led to the predominant geological model that incorporates four distinct layers: a crust and a mantle (composed largely of silicate minerals) and an outer core and inner core composed of nickel-iron.

According to seismologists from The Australian National University (ANU), data obtained in a recent study has shed new light on the deepest parts of Earth’s inner core. In a paper that appeared in Nature Communications, the team reports finding evidence for another distinct layer (a solid metal ball) in the center of Earth’s inner core – an “innermost inner core.” These findings could shed new light on the evolution of our planet and lead to revised geological models of Earth that include five distinct layers instead of the traditional four.

February 23, 2023February 23, 2023 by Matt Williams

How are Mars Rocks Getting “Shocked” by Meteorite Impacts?

Jezero Crater on Mars is the landing site for NASA's Mars 2020 rover. Image Credit: NASA/JPL-Caltech/ASU

On Mars, NASA’s Perseverance rover is busy collecting rock samples that will be retrieved and brought back to Earth by the Mars Sample Return (MSR) mission. This will be the first sample-return mission from Mars, allowing scientists to analyze Martian rocks directly using instruments and equipment too large and cumbersome to send to Mars. To this end, scientists want to ensure that Perseverance collects samples that satisfy two major science goals – searching for signs of life (“biosignatures”) and geologic dating.

To ensure they select the right samples, scientists must understand how rock samples formed and how they might have been altered over time. According to a new NASA study, Martian rocks may have been “shocked” by meteorite impacts during its early history (the Late Heavy Bombardment period). The role these shocks played in shaping Martian rocks could provide fresh insights into the planet’s geological history, which could prove invaluable in the search for evidence of past life on Mars.

December 8, 2022December 8, 2022 by Matt Williams

There's a Giant Magma Plume on Mars, Bulging the Surface out Across a Vast Region

Lava flows in Mars' Elysium Planitia region have left a rather good likeness of a woolly mammoth or elephant. The region is known for some of the planet's youngest lavas - this one may formed in the past 100 million years.

Billions of years ago, Mars was a much different place than it is today. Its atmosphere was thicker and warmer, liquid water flowed on its surface, and the planet was geologically active. Due to its lower gravity, this activity led to the largest volcanoes in the Solar System (Olympus Mons and the Thetis Mons region) and the longest, deepest canyon in the world (Valles Marineris). Unfortunately, Mars’ interior began to cool rapidly, its inner core solidified, and geological activity largely stopped. For some time, geologists have believed that Mars was essentially “dead” in the geological sense.

However, recent studies have provided seismic and geophysical evidence that Mars may still be “slightly alive.” In a recent study, scientists from the University of Arizona (ASU) challenged conventional views of Martian geodynamic evolution by discovering evidence of an active mantle plume pushing its way through the crust, causing earthquakes and volcanic eruptions. Combined with some serious marsquakes recorded by NASA’s InSight lander, these finding suggests that there is still some powerful volcanic action beneath the surface of Mars.

October 19, 2022October 19, 2022 by Matt Williams

The Asteroid That Killed the Dinosaurs Also Flooded the World's Coastlines With a Catastrophic Tsunami

Earth and possibly its Moon were hit by impactors that killed off the dinosaurs — Artistic rendition of the Chicxulub impactor striking ancient Earth, with Pterosaur observing. Could pieces of the same impact swarm have hit the Moon, too? Credit: NASA

For decades, scientists have theorized that a massive impact caused the Cretaceous-Paleogene extinction event. This event occurred about 66 million years ago and caused the mass extinction of about 75% of all plant and animal species on Earth (including the non-avian dinosaurs). With the discovery of the massive Chicxulub crater in the Yucatan Peninsula (southern Mexico) in the 1970s, scientists concluded that they’d found the impact responsible. Based on all the available data, the Chicxulub Impact event is believed to have been as powerful as 100,000 billion metric tons (110,231 U.S tons) of TNT.

This blast was more powerful than all the nuclear devices in the world combined and sent an estimated 25 trillion metric tons (~27.5 US tons) of hot dust, ash, and steam into the atmosphere, creating a global winter. But according to new research led by the University of Michigan, an international team of geologists has determined that the impact also created a global tsunami. According to their findings, this tsunami was 30,000 times more powerful than the 2004 Indian Ocean tsunami, one of the largest and most devastating tsunamis on record.