Click for full image.
Cool image time! In this week’s exploration of Martian geology that is reminiscent of Earth-based lava geology, today’s image is of a collapse pit in Ceraunius Fossae, the vast region of north-south fissures found to the south of the volcano Alba Mons. The photo to the right, cropped to post here, zooms in on that pit.
The picture was part of the most recent image release from the high resolution camera on Mars Reconnaissance Orbiter (MRO). What makes it especially interesting is the sharpness of its rim, in comparison to the collapse channel to the east. This suggests the pit is younger and fresher than the channel, and happened more recently. This also implies that the voids below the ground in which the surface is sinking are either still there, or due to on-going processes might be still be forming (like caves are on Earth).
For example, if there is underground ice, temperature changes or even thermal heat from the nearby giant volcanoes could melt that underground ice periodically, allowing it to flow and erode the surrounding material, forming voids. That this pit is located at 30 degrees north latitude, just inside the northern hemisphere band where glaciers are found, adds weight to this possibility.
The image below, reduced and rotated so that north is to the left, shows the entire sequence of collapse channels, with the more distinct pit from above in the bottom center of the picture.
To the right is the same overview map that I posted yesterday, amended to show yesterday’s image with a black box and today’s image by the white box.
The void that might be causing this collapse is however not likely to be a lava tube (though this possibility cannot yet be entirely dismissed). The numerous giant fissures in Ceraunius Fossae are mostly not the result of a collapses because of underlying lava tubes, but instead are what geologists call grabens, formed when tectonic forces pull apart the surface, created gaps that material can slide or collapse into.
These fissures highlight the unusual nature of Alba Mons itself. Despite being the largest Martian volcano in terms of area, far greater than Olympus Mons (as shown in the overview map), it is not very tall. While the fissures suggest they were formed by the volcano itself as it pushed upward, it is also possible that a geological interaction with the other nearby volcanoes, Olympus Mons and the chain of three to its west, contributed. In addition, buried glaciers have been documented scattered about within Ceraunius Fossae, and there is evidence in the area of erosion due to some sort of flows, either water, ice, or lava.
Not surprisingly, at this time no one has yet disentangled these facts. We simply don’t know enough. Our knowledge, while vastly improved by the data from our Mars orbiters, is still too superficial. We need to land there and dig down into the surface.
Who wants to go?
I must unfortunately ask you for your financial support because I do not depend on ads and rely entirely on the generosity of readers to keep Behind the Black running. You can either make a one time donation for whatever amount you wish, or you sign up for a monthly subscription ranging from $2 to $15 through Paypal or $3 to $50 through Patreon.
Your support will allow me to continue covering science and culture as I have for the past twenty years, independent and free from any outside influence.
Your support is even more essential to me because I not only keep this site free from advertisements, I do not use the corrupt social media companies like Google, Twitter, and Facebook to promote my work. I depend wholly on the direct support of my readers.
You can provide that support to Behind The Black with a contribution via Patreon or PayPal. To use Patreon, go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation. For PayPal click one of the following buttons:
If Patreon or Paypal don't work for you, you can support Behind The Black directly by sending your donation by check, payable to Robert Zimmerman, to
Behind The Black
c/o Robert Zimmerman
Cortaro, AZ 85652
Or you can donate by using Zelle through your bank. You will need to give my name and email address (found at the bottom of the "About" page). The best part of this electronic option is that no fees will be deducted! What you donate will be what I receive.