New findings using data from NASA’s Mars Reconnaissance Orbiter show that gullies on modern Mars are likely not being formed by flowing liquid water. This new evidence will allow researchers to further narrow theories about how Martian gullies form, and reveal more details about Mars’ recent geologic processes.
Scientists use the term “gully” for features on Mars that share three characteristics in their shape: an alcove at the top, a channel, and an apron of deposited material at the bottom. Gullies are distinct from another type of feature on Martian slopes, streaks called “recurring slope lineae,” or RSL, which are distinguished by seasonal darkening and fading, rather than characteristics of how the ground is shaped.
Water in the form of hydrated salt has been identified at RSL sites.
The new study focuses on gullies and their formation process by adding composition information to previously acquired imaging.
Researchers from the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, examined high-resolution compositional data from more than 100 gully sites throughout Mars. These data, collected by the orbiter’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), were then correlated with images from the same spacecraft’s High Resolution Imaging Science Experiment (HiRISE) camera and Context Camera (CTX).
The findings showed no mineralogical evidence for abundant liquid water or its by-products, thus pointing to mechanisms other than the flow of water – such as the freeze and thaw of carbon dioxide frost – as being the major drivers of recent gully evolution.
The findings were published in Geophysical Research Letters.
Gullies are a widespread and common feature on the Martian surface, mostly occurring between 30 and 50 degrees latitude in both the northern and southern hemispheres, generally on slopes that face toward the poles. On Earth, similar gullies are formed by flowing liquid water; however, under current conditions, liquid water is transient on the surface of Mars, and may occur only as small amounts of brine even at RSL streaks. The lack of sufficient water to carve gullies has resulted in a variety of theories for the gullies’ creation, including different mechanisms involving evaporation of water and carbon dioxide frost.
“The HiRISE team and others had shown there was seasonal activity in gullies – primarily in the southern hemisphere – over the past couple of years, and carbon dioxide frost is the main mechanism they suspected of causing it. However, other researchers favored liquid water as the main mechanism,” said Jorge Núñez of APL, the lead author of the paper.
“What HiRISE and other imagers were not able to determine on their own was the composition of the material in gullies, because they are optical cameras. To bring another important piece in to help solve the puzzle, we used CRISM, an imaging spectrometer, to look at what kinds of minerals were present in the gullies and see if they could shed light on the main mechanism responsible.”
Núñez and his colleagues took advantage of a new CRISM data product called Map-projected Targeted Reduced Data Records. It allowed them to more easily perform their analyses and then correlate the findings with HiRISE imagery.
“On Earth and on Mars, we know that the presence of phyllosilicates – clays – or other hydrated minerals indicates formation in liquid water,” Núñez said. “In our study, we found no evidence for clays or other hydrated minerals in most of the gullies we studied, and when we did see them, they were erosional debris from ancient rocks, exposed and transported downslope, rather than altered in more recent flowing water. These gullies are carving into the terrain and exposing clays that likely formed billions of years ago when liquid water was more stable on the Martian surface.”
Other researchers have created computer models that show how sublimation of seasonal carbon dioxide frost can create gullies similar to those observed on Mars, and how their shape can mimic the types of gullies that liquid water would create. The new study adds support to those models.
APL built and operates CRISM, one of six instruments with which the Mars Reconnaissance Orbiter project has been examining Mars since 2006. NASA’s Jet Propulsion Laboratory, a division of the Caltech in Pasadena, California manages the project for the NASA Science Mission Directorate in Washington. Lockheed Martin Space Systems of Denver built the orbiter and supports its operations.
IMAGE….The highly incised Martian gullies seen in the top image resemble gullies on Earth that are carved by liquid water. However, when the gullies are observed with the addition of mineralogical information (bottom), no evidence for alteration by water appears.
The pictured area spans about 2 miles (3 kilometers) on the eastern rim of Hale Crater. The High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter took the visible-light image. Color-coded compositional information added in the lower version comes from the same orbiter’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Color coding in light blue corresponds to surface composition of unaltered mafic material, of volcanic origin. Mafic material from the crater rim is carved and transported downslope along the gully channels. No hydrated minerals are observed within the gullies, in the data from CRISM, indicating limited interaction or no interaction of the mafic material with liquid water. These findings and related observations at about 100 other gully sites on Mars suggest that a mechanism not requiring liquid water may be responsible for carving these gullies on Mars. (Gullies on Mars are a different type of feature than seasonal dark streaks called recurring slope lineae or RSL; water in the form of hydrated salt has been identified at RSL sites.)
The HiRISE image is a portion of HiRISE observation PSP_002932_1445. The lower image is from the same HiRISE observation, with a CRISM mineral map overlaid.
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Located on the Colorado Plateau in northern Arizona, the Vermilion Cliffs National Monument in Arizona includes the Paria Canyon-Vermilion Cliffs Wilderness. This remote and unspoiled, 280,000-acre Monument - a part of the BLM’s National Conservation Lands - is a geologic treasure, containing a variety of diverse landscapes from the Paria Plateau, Vermilion Cliffs, Coyote Buttes, and Paria Canyon.
Visitors enjoy scenic views of towering cliffs and deep canyons. Paria Canyon offers an outstanding three to five day wilderness backpacking experience. The colorful swirls of cross-bedded sandstone in Coyote Buttes are an international hiking destination.
A permit is required for hiking in Coyote Buttes North (the Wave), Coyote Buttes South, and for overnight trips within Paria Canyon. Visit the BLM Arizona’s website to learn more about this beautiful area and plan your visit.
Nice view and a geologically interesting environment - these rocks, on the south shore of Crete, are very close to one of the active faults on the island that is pushing the whole block upward. The fault zone is just beyond those hills.
I’ve been a fan of Macklemore ever since he released his mixtape The Unplanned Mixtapeback in 2009. He’s one of the realest rappers of all time, and after listening to Fallin you’ll understand why. Macklemore lived a rough life riddled with depression and drug addiction, and he’s obviously not afraid to beautifully illustrate his pain and alcohol drenched past through his music. Fallin goes exceptionally hard. It’s my second favorite song off The Unplanned Mixtape, my favorite song being Church (ft. Geologic), which I rated a 9.7.
If you’re ever confused by exactly what the term “real hip-hop” means, this song is a perfect template for its definition, or for at least what I perceive it as. Real hip-hop is hip-hop that depicts truth and the complicated reality of our chaotic world through the emotional perceptions of the artist.
Ending the weekend with a #NatureSelfie of BLMer Bob Wick (middle photo) along with a few Wick photos of the Vermilion Cliffs National Monument in Arizona.
This remote and unspoiled 280,000-acre Monument - a part of the BLM’s National Conservation Lands - contains a diversity of geologic landscapes from the Paria Plateau, Vermilion Cliffs, Coyote Buttes, and Paria Canyon.
Share your own #NatureSelfie this week for #EarthDay!
A skylight is not just a view to the world above you, but a window to the world beneath. In this photo, taken last month on the Puʻu ʻŌʻō crater at Kīlauea in Hawaii, a volcanic skylight reveals a river of molten rock, drifting just below the charred surface. It’s a powerful reminder of the forces at work below us. Photo by U.S. Geological Survey.
Chris Hillary turned his back on advertising after a decade of creative frustration and late nights eating Vietnamese food at his desk. In 2014 he slipped away to South America to pursue a hunch that taking photos would make him happier. The hunch was good.
It was one of the most magical natural wonders I’ve ever seen. It’s a twisted oil painting. A geological acid trip. A prehistoric Magic Eye. You could lose your mind staring into its abstract patterns. I could’ve floated through its tunnels for days and still found fascinating formations.
Thanks to @cynrk for the note about Arizona’s birthday!
While younger than Oregon (statehood in 1912), equally amazing in very different ways. Our post highlights some of the most interesting things about BLM Arizona public lands - petroglyphs, unique wildlife, cool cactus and other plants, out-of-this world geologic formations and so much more. A lot to love about Arizona on Valentine’s Day.
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#Genus - Dactylioceras gracile sp.
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Location - Limestone from Isle of #Skye, Upper Lias, UK #scotland
GEO: That’s one of the things about Seattle that’s cool. It’s big enough to be a city but small enough to be a town. There’s a global identity, but there’s also very local identity. We grew up, we spent time here, like I know a little bit about the history of Eritrea, and the Philippines, and Vietnam, and Cambodia, because I have friends that all came from these different places. So, New York and L.A., obviously they’re cosmopolitan cities, obviously there’s people from all over the world there, but in my experience the kind of mixing among those communities that happens here doesn’t happen in those other places.
Happy Birthday, Colorado! On this day in 1876, Colorado became a state; we celebrate with a amazing photos from Handies Peak Wilderness Study Area - one of our favorites.
The scenic quality of the Handies Peak Wilderness Study Area in Colorado is outstanding due to the interaction of mountainous landforms; multi-colored rock strata; diverse vegetation; and vast, open vistas. Handies Peak itself rises 14,048 feet over the area and is the highest point of land managed by the Bureau of Land Management outside of Alaska. This WSA also hosts 12 other peaks that rise over 13,000 feet, three major canyons, numerous small drainages, glacial cirques and three alpine lakes. The landscape a variety of volcanic, glacial and Precambrian formations. A rock glacier formation is also located at the head of American Basin.
This is an area perfect for hiking, backpacking, camping, mountain climbing and photography. Guaranteed to inspire!
Photos by Bob Wick, Wilderness Specialist for BLM’s National Conservation Lands