Boxwork in the dry Martian tropics
Click for original image.
Cool image time! The picture to the right, cropped and enhanced to post here, was taken on July 17, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as boxwork, a pattern of intersecting straight ridges criss-crossing each other in a generally random manner.
The ridges themselves are very small, only a few feet high. To make them more visible I have purposely cropped this section without reducing its resolution. I have also increased the contrast.
What caused them? According to this paper [pdf] about similar boxwork found on Mount Sharp in Gale Crater, the boxwork “formed when cements filled existing pore spaces and fractures in fractured rock, and these cements were left as topographic ridges after erosion.”
In other words, the surface hardened, then fractured. Later more resistent material, likely lava, filled the cracks. When erosion later stripped the top surface away, the lava was more resistent and so became the ridges we now see.
On the overview map to the right, the white dot about 275 miles east of Curiosity in Gale Crater marks the location. The rectangle in the inset shows the area covered by the picture above. This boxwork covers the floor of a mile-wide bowl, set between a larger 40-mile-wide region of plateaus, knobby plains, and larger ridges. This larger patch of rocky terrain is in turn surrounded by the Medusa Fossae Formation, the largest volcanic ash deposit on Mars. In Medusa the bedrock is generally covered deeply by that ash. Here however we are looking mostly at bedrock.
Though lava is the likely material that filled the cracks and formed these ridges, the fracturing is often theorized to have involved water. Initially the ground was impregnated with water or ice, and as that sublimated away the ground dried and formed the kind of polygonal cracks seen in dried mud on Earth.
Though this boxwork (as well as the boxwork on Mount Sharp) is in the middle of the dry tropics of Mars, its existence suggests the possibility of past water processes that are worth investigation. Thus, sometime in the next few years the Curiosity rover team hopes to reach the boxwork high on Mount Sharp to get a closer look.
Readers!
Please consider supporting my work here at Behind the Black. Your support allows me the freedom and ability to analyze objectively the ongoing renaissance in space, as well as the cultural changes -- for good or ill -- that are happening across America. Fourteen years ago I wrote that SLS and Orion were a bad ideas, a waste of money, would be years behind schedule, and better replaced by commercial private enterprise. Only now does it appear that Washington might finally recognize this reality.
In 2020 when the world panicked over COVID I wrote that the panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
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Click for original image.
Cool image time! The picture to the right, cropped and enhanced to post here, was taken on July 17, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the scientists label as boxwork, a pattern of intersecting straight ridges criss-crossing each other in a generally random manner.
The ridges themselves are very small, only a few feet high. To make them more visible I have purposely cropped this section without reducing its resolution. I have also increased the contrast.
What caused them? According to this paper [pdf] about similar boxwork found on Mount Sharp in Gale Crater, the boxwork “formed when cements filled existing pore spaces and fractures in fractured rock, and these cements were left as topographic ridges after erosion.”
In other words, the surface hardened, then fractured. Later more resistent material, likely lava, filled the cracks. When erosion later stripped the top surface away, the lava was more resistent and so became the ridges we now see.
On the overview map to the right, the white dot about 275 miles east of Curiosity in Gale Crater marks the location. The rectangle in the inset shows the area covered by the picture above. This boxwork covers the floor of a mile-wide bowl, set between a larger 40-mile-wide region of plateaus, knobby plains, and larger ridges. This larger patch of rocky terrain is in turn surrounded by the Medusa Fossae Formation, the largest volcanic ash deposit on Mars. In Medusa the bedrock is generally covered deeply by that ash. Here however we are looking mostly at bedrock.
Though lava is the likely material that filled the cracks and formed these ridges, the fracturing is often theorized to have involved water. Initially the ground was impregnated with water or ice, and as that sublimated away the ground dried and formed the kind of polygonal cracks seen in dried mud on Earth.
Though this boxwork (as well as the boxwork on Mount Sharp) is in the middle of the dry tropics of Mars, its existence suggests the possibility of past water processes that are worth investigation. Thus, sometime in the next few years the Curiosity rover team hopes to reach the boxwork high on Mount Sharp to get a closer look.
Readers!
Please consider supporting my work here at Behind the Black. Your support allows me the freedom and ability to analyze objectively the ongoing renaissance in space, as well as the cultural changes -- for good or ill -- that are happening across America. Fourteen years ago I wrote that SLS and Orion were a bad ideas, a waste of money, would be years behind schedule, and better replaced by commercial private enterprise. Only now does it appear that Washington might finally recognize this reality.
In 2020 when the world panicked over COVID I wrote that the panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.
3. A Paypal Donation or subscription:
4. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652
You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above.
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