Click for full image.
Today’s cool image is also today’s picture of the day from the science team of the high resolution camera on Mars Reconnaissance Orbiter (MRO. That picture, rotated, cropped, and reduced to post here, can be seen to the right. As the caption authors Sharon Wilson and Sarah Sutton write:
The smooth volcanic surfaces in the Gordii Fossae region are sometimes interrupted by long, narrow troughs, or fissures. These fissures form when underground faults, possibly involving magma movement, reach the near-surface, allowing material to collapse into pits or an elongated trough. This fissure appears to have erupted material that flowed onto the surface.
If you use your imagination, this trough resembles a gecko with its long tail and web-shaped feet!
This impression is even more evident in the wider image taken by MRO’s context camera below.
Click for full image.
To my eye, the gecko is about to swallow a very big bug. It also appears to me to be followed by second, third, and maybe a third gecko, less visible because they are partly hidden by mist.
I know, I know, I am letting my imagination run away with me. What the wider image actually illustrates quite clearly are the underground fissures in this region, all aligned in a northwest to a southeast direction.
The overview map below helps even more to explain why these fissures exist. When Mount Olympus was growing, it imposed two major changes on this landscape. First the upward pressure of the volcano’s magma caused radiating cracks to occur in the surrounding terrain. Second, the volcano flooded that surrounding terrain with lava, producing the smooth lava flood plains. Because those lava flood plains are relatively young, they have few craters.
The result is a very smooth surface periodically interspersed with long narrow sinks. That one of those sinks now can be imagined by Earthlings as resembling a gecko is mere happenstance.
The overview map also underlines the difference between lava flows on Earth and on Mars. The distance from the caldera’s eastern rim and this fissure is about 140 miles. While much of the lava here probably came from much closer vents, the ability of Martian lava to flow faster and farther means that the volcano was able to inundate a much larger area than is possible on Earth.
When human geologists finally get to Olympus Mons I suspect they are going to end up mapping out a volcanic history that is truly monumental, far exceeding anything they can presently imagine.
Please consider donating to Behind the Black, by giving either a one-time contribution or a regular subscription, as outlined in the tip jar below. 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 keep this site free from advertisements and do not participate in corrupt social media companies like Google, Twitter, and Facebook. 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