Tag Archives: canyon

One of Titan's huge methane sea. In the upper left you can see a network of methane filled canyon-structures called the Vid Flumina. Credit: NASA

Cassini finds canyons flooded with liquid hydrocarbons on Titan

One of Titan's huge methane sea. In the upper left you can see a network of methane filled canyon-structures called the Vid Flumina. Credit: NASA

One of Titan’s huge methane sea. In the upper left you can see a network of methane filled canyon-structures called the Vid Flumina. Credit: NASA

NASA’s ever-resourceful Cassini probe found steep-sided canyons on Saturn’s moon Titan. These geological formations are filled with liquid hydrocarbons like methane — the first evidence of both liquid-filled channels and hundreds of meters deep canyons on Titan. Remarkably, these canyons must have formed very similarly to those on Earth, like the Grand Canyon in Arizona.

These channels form a network branching out of the large Ligeia Mare sea, located on the northern side of the moon. They’re less than half a mile wide, with some slopes steeper than 40 degrees. The canyons are quite deep though, measuring anywhere from 790 to 1,870 feet (240 to 570 meters) from top to bottom.

False-color near infrared view of Titan's northern hemisphere, showing its seas and lakes. Orange areas near some of them may be deposits of organic evaporite left behind by receding liquid hydrocarbon. Credit: Wikimedia Commons

False-color near infrared view of Titan’s northern hemisphere, showing its seas and lakes. Orange areas near some of them may be deposits of organic evaporite left behind by receding liquid hydrocarbon. Credit: Wikimedia Commons

To find these channels, geologists working at NASA had to combine altimetry and radio wave readings as direct observations are made impossible by the thick hazy atmosphere surrounding Titan. Pings of radio waves bounced back and forth between the surface of the moon and the Cassini probe to determine the height of features. Then, the way radio signals reflected off surfaces told researchers what they were made off.

Since the signal was very similar to that observed on Titan’s rich hydrocarbon seas, the researchers concluded that the matter which covers the channels must be made of the same stuff. Previously, some suggested these sort of channels could be filled with saturated sediment, but the dark material seems much likelier to be liquid at this stage.

[ALSO SEE] NASA wants to explore Titan’s methane oceans with a robot submarine

As to the formation of these geological features, the NASA geologists posit processes akin to those found on Earth: uplift of terrain, changes in sea level (methane sea instead of water) or both.

“It’s likely that a combination of these forces contributed to the formation of the deep canyons, but at present it’s not clear to what degree each was involved. What is clear is that any description of Titan’s geological evolution needs to be able to explain how the canyons got there,” said Valerio Poggiali of the University of Rome, a Cassini radar team associate and lead author of the study which was published in the Geophysical Research Letters journal.

On Earth, such examples of canyon-carving processes are abundant, such as the canyons found along the Colorado River in Arizona. Uplift power erosion is what drove the formation of the Grand Canyon, while for those formed by variations in water level we can give Lake Powell as an example.

“Earth is warm and rocky, with rivers of water, while Titan is cold and icy, with rivers of methane. And yet it’s remarkable that we find such similar features on both worlds,” said Alex Hayes, a Cassini radar team associate at Cornell University, Ithaca, New York, and a co-author of the study.

Though Cassini made its flyby around Titan in 2013, scientists are still making sense of the wealth of data it beamed back. They expect we’ll soon have a very comprehensive picture of Titan’s landscape, but also of the forces involved in its formation.

Pluto’s Charon reveals colorful and violent past

NASA’s New Horizons shuttle wasn’t only taking mind blowing photos of Pluto, it was also peeking at Pluto’s moons, especially Charon – the largest one. The latest set of images analyzed by NASA researchers revealed quite a busy past, filled with violence and geologic activity.

Charon in Enhanced Color NASA’s New Horizons captured this high-resolution enhanced color view of Charon just before closest approach on July 14, 2015. The image combines blue, red and infrared images taken by the spacecraft’s Ralph/Multispectral Visual Imaging Camera (MVIC); the colors are processed to best highlight the variation of surface properties across Charon. Charon’s color palette is not as diverse as Pluto’s; most striking is the reddish north (top) polar region, informally named Mordor Macula. Charon is 754 miles (1,214 kilometers) across; this image resolves details as small as 1.8 miles (2.9 kilometers).
Credits: NASA/JHUAPL/SwRI

Charon is the largest and best studied moon of Pluto. It is a very large moon in comparison to its parent body, Pluto, and some astronomers have argued that Charon itself should be considered a dwarf planet like Pluto, and not a moon. nlike Pluto’s surface, which is composed of nitrogen and methane ices, Charon’s surface appears to be dominated by the less volatile water ice. The south polar area is dominated by a very large dark area informally dubbed “Mordor” by the New Horizons team. Aside from Mordor, however, New Horizons imaged very few other impact craters on Charon and found a youthful surface, adding support to the above theory that Charon is geologically active and thus probably differentiated (meaning it has a crust, a mantle and a core).

“We thought the probability of seeing such interesting features on this satellite of a world at the far edge of our solar system was low,” said Ross Beyer, an affiliate of the New Horizons Geology, Geophysics and Imaging (GGI) team from the SETI Institute and NASA Ames Research Center in Mountain View, California, “but I couldn’t be more delighted with what we see.”

For starters, the features are incredibly visible – you can see craters, ridges, and even fractures on its surface, but the most spectacular feature is definitely a huge canyon. The canyon stretches more than 1,000 miles (1,600 kilometers) across the entire face of Charon and likely around onto Charon’s far side, four times larger than the Grand Canyon, indicating a huge geologic upheaval in Charon’s past.

“It looks like the entire crust of Charon has been split open,” said John Spencer, deputy lead for GGI at the Southwest Research Institute in Boulder, Colorado. “With respect to its size relative to Charon, this feature is much like the vast Valles Marineris canyon system on Mars.”

High-resolution images of Charon were taken by the Long Range Reconnaissance Imager on NASA’s New Horizons spacecraft, shortly before closest approach on July 14, 2015, and overlaid with enhanced color from the Ralph/Multispectral Visual Imaging Camera (MVIC). Charon’s cratered uplands at the top are broken by series of canyons, and replaced on the bottom by the rolling plains of the informally named Vulcan Planum. The scene covers Charon’s width of 754 miles (1,214 kilometers) and resolves details as small as 0.5 miles (0.8 kilometers).
Credits: NASA/JHUAPL/SwRI

They also found that the moon’s southern part has way fewer craters than the northern part. The smoothness of the plains, as well as their grooves and faint ridges, are clear signs of wide-scale resurfacing. This could be the effect of a kind of cold volcanic activity, called cryovolcanism.

“The team is discussing the possibility that an internal water ocean could have frozen long ago, and the resulting volume change could have led to Charon cracking open, allowing water-based lavas to reach the surface at that time,” said Paul Schenk, a New Horizons team member from the Lunar and Planetary Institute in Houston.

Right now, the existence (and extent) of geological features on Charon has taken both astronomers and geologists by surprise, but they couldn’t be more thrilled. The good news is that even more pictures of Charon are currently being sent by New Horizons, and some of them will come in even better resolution. We’ll keep you posted as that happens.

This composite of enhanced color images of Pluto (lower right) and Charon (upper left), was taken by NASA’s New Horizons spacecraft as it passed through the Pluto system on July 14, 2015. This image highlights the striking differences between Pluto and Charon. The color and brightness of both Pluto and Charon have been processed identically to allow direct comparison of their surface properties, and to highlight the similarity between Charon’s polar red terrain and Pluto’s equatorial red terrain. Pluto and Charon are shown with approximately correct relative sizes, but their true separation is not to scale. The image combines blue, red and infrared images taken by the spacecraft’s Ralph/Multispectral Visual Imaging Camera (MVIC).
Credits: NASA/JHUAPL/SwRI

“I predict Charon’s story will become even more amazing!” said mission Project Scientist Hal Weaver, of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

Photographs of (A) Woody's Cove (person, for scale, circled), (B) the approximately 50-meter high headwall of Stubby Canyon, (C) the downstream-most waterfall at Pointed Canyon, (D) fluted and polished notch at the rim of Stubby Canyon, (E) upstream-most waterfall at Pointed Canyon, and (F) upstream-most abandoned channel.

Canyons both on Earth and Mars may have been made by megafloods

  • A huge megaflood may have carved the U-shaped canyons we can now see in Idaho some 46,000 years ago.
  • The similarities suggest that the same phenomenon occurred on Mars as well were similar geological formations were found.
Photographs of (A) Woody's Cove (person, for scale, circled), (B) the approximately 50-meter high headwall of Stubby Canyon, (C) the downstream-most waterfall at Pointed Canyon, (D) fluted and polished notch at the rim of Stubby Canyon, (E) upstream-most waterfall at Pointed Canyon, and (F) upstream-most abandoned channel.

Photographs of (A) Woody’s Cove (person, for scale, circled), (B) the approximately 50-meter high headwall of Stubby Canyon, (C) the downstream-most waterfall at Pointed Canyon, (D) fluted and polished notch at the rim of Stubby Canyon, (E) upstream-most waterfall at Pointed Canyon, and (F) upstream-most abandoned channel.

After studying several U-shaped canyons in south-central Idaho, US, geologists at Caltech propose that these characteristic formations were made by megafloods some millions of years ago. Interestingly enough, these features are very akin to some canyons observed on Mars via satellite, suggesting that these too may have been formed by huge floods.

Canyons sparked by a dramatic event

The amphitheater-headed canyons of Malad Gorge State Park, Idaho  are sculpted in a flat plain made from basalt – a volcanic rock. Two canyons in particular, Woody’s Cove and Stubby Canyon, are characterized by tall vertical headwalls, roughly 150 feet high, that curve around to form an amphitheater. These geological structures were formed as lava hardened in several layers. As the lava cooled and contracted, vertical cracks emerged across the entire layer of lava-turned-basalt. As each additional sheet of lava covered the same land, it too cooled and cracked vertically, leaving a wall that, when exposed, looks like stacks of tall blocks, slightly offset from one another with each additional layer. This type of structure is called columnar basalt.

Two canyons in Malad Gorge, Woody's Cove and Stubby Canyon, are characterised by tall vertical headwalls, roughly 150 feet high that curve around to form an amphitheatre.

Two canyons in Malad Gorge, Woody’s Cove and Stubby Canyon, are characterised by tall vertical headwalls, roughly 150 feet high that curve around to form an amphitheatre.

The columnar basalt formation theory is well understood – no debate here. What’s controversial is how canyons like Woody’s Cove and Stubby Canyon got their curved shape. One widely accepted theory says that “groundwater sapping,” a process in which springs at the bottom of the canyon gradually carve tunnels at the base of the rock  collapsing the basalt columns, explains the formations.

The theory didn’t convince the Caltech researchers, though. Their objection is based on two grounds: there is no evidence of undercutting in these particular canyon formations and, second, undercutting should leave large boulders in place at the foot of the canyon.

“These blocks are too big to move by spring flow, and there’s not enough time for the groundwater to have dissolved them away,” Caltech professor of geology Michael P. Lamb explains, “which means that large floods are needed to move them out. To make a canyon, you have to erode the canyon headwall, and you also have to evacuate the material that collapses in.”

Back through time

After studying rock samples at the location, the Caltech geologists reason that the only viable explanation is that these canyons were sculpted following waterfall erosion during a large flood event. There’s no flowing water in the vicinity of Woody’s Cove and Stubby Canyon today, however during a different time there could have.  A flood of this magnitude could also carry boulders downstream, leaving behind the amphitheater canyons we see today without massive boulder piles at their bottoms and with no existing watercourses.

Additionally, the researchers found scour marks on surface rocks on the plateau above the canyons, clear evidence that these rocks were subjected to water discharge containing sediment.

Taken together, the evidence from Malad Gorge, Lamb says, suggests that “amphitheater shapes might be diagnostic of very large-scale floods, which would imply much larger water discharges and much shorter flow durations than predicted by the previous groundwater theory.” Lamb points out that although groundwater sapping “is often assumed to explain the origin of amphitheater-headed canyons, there is no place on Earth where it has been demonstrated to work in columnar basalt.”

U-shaped canyons, such as those in Idaho's Malad Gorge State Park, are relatively rare on Earth but common on the Martian surface.

U-shaped canyons, such as those in Idaho’s Malad Gorge State Park, are relatively rare on Earth but common on the Martian surface.

When did this supposed flood event occurred, though? The key came following surface rock dating, which was made using a very fascinating technique. As cosmic rays hit the earth’s surface, these interacts with rocks producing alternate versions of noble gas elements, or isotopes, called cosmogenic nuclides. By measuring the accumulation of nuclides in a certain mineral, while taking into account the cosmic ray flux, the scientists were able to determine the time that rocks has been sitting at Earth’s surface.

Moving to another planet

Apparently, rock samples from the heads of Woody’s Cove and Stubby Canyon had been exposed for the same length of time, approximately 46,000 years  suggesting this is when the flood occurred. The implications of the U-shaped canyons may stretch far beyond our planet, however.

“A very popular interpretation for the amphitheater-headed canyons on Mars is that groundwater seeps out of cracks at the base of the canyon headwalls and that no water ever went over the top,” Lamb says.

Judging from the evidence in Idaho, however, it seems more likely that on Mars, as on Earth, amphitheater-headed canyons were created by enormous flood events, suggesting that Mars was once a very watery planet.  The researchers are now developing models simulating canyon formation by megafloods.

‘We intend to test the model against our data at Malad Gorge and to apply it to specific examples on Mars,’ Professor Lamb said.

‘Using Earth as our guide, the early history of Mars surface environments, including the amounts and duration of flowing surface water, is waiting to be discovered through careful analysis of the landforms and sedimentary deposits on the red planet.’

 

Mega canyon discovered under Greenland ice sheet

Geophysical data from Greenland have revealed the existence of a canyon comparable in size with the Grand Canyon beneath the ice sheet.

The canyon has the characteristics of a winding river channel and is over 750 km long and it is often as deep as 800 m. This immense feature is thought to predate humanity – it came to be several million years before the Antarctic ice sheet was developed.

“One might assume that the landscape of the Earth has been fully explored and mapped,” said Jonathan Bamber, professor of physical geography at the University of Bristol in the United Kingdom, and lead author of the study. “Our research shows there’s still a lot left to discover.”

Scientists used thousands of kilometers of airborne radar data collected by NASA and researchers from the United Kingdom and Germany over several decades, and managed to puzzle together the main characteristics of the Greenland canyon. They found that the geologic feature starts from almost the center of the island and ends beneath the Petermann Glacier fjord in northern Greenland.

At certain wavelengths, radar waves can travel through the ice, but bounce off the solid rock underneath. This enables us to map the depth of the canyon – the longer it takes for the wave to return, the deeper the canyon is.

“Two things helped lead to this discovery,” said Michael Studinger, IceBridge project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “It was the enormous amount of data collected by IceBridge and the work of combining it with other datasets into a Greenland-wide compilation of all existing data that makes this feature appear in front of our eyes.”

Geologists believe the canyon plays an important role in transporting sub-glacial meltwater from the interior of Greenland to the edge of the ice sheet into the ocean. Existing evidence (this canyon included) suggests that before the ice sheet existed, some 4 million years ago, the canyon hosted an extensive river system which flowed from the interior to the coast.

“It is quite remarkable that a channel the size of the Grand Canyon is discovered in the 21st century below the Greenland ice sheet,” said Studinger. “It shows how little we still know about the bedrock below large continental ice sheets.”

For more information about IceBridge, the operation which led to this discovery, check out their website. The IceBridge campaign will return to Greenland in March 2014 to gather more data and develop a more conclusive picture of the subglacial features in Greenland.

Via NASA.