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Cool image time! The photo to the right, cropped, reduced, and enhanced to post here, was taken on July 24, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The scientists label this “platy-ridged lava” but to my eye this more resembles lava ice bergs trapped within a now frozen lava stream flowing I think from the northeast to the southwest.
My guess that the flow follows that direction is based on two bits of data. First, the shape of the lava ice flows suggests vaguely a flow to the southwest. The wiggling black ridges inside the streams suggest that these flows occurred in two parts, a stronger wide flow that narrowed as the lava on the edges hardened. When the edges solidified the interior flow scraped against it, forming the wiggling ridges.
Second, the location of this image, as shown on the overview map below, strongly suggests the lava streams flowed to the southwest.
The white cross marks the position of these lava icebergs, southwest of the main vent for the Athabasca Valles lava flood plain, Mars’ youngest large volcanic eruption that covered in mere weeks an area comparable to Great Britain. The Athabasca eruption flowed first to the southwest, than split into two flows, one to the west and the second to southeast.
Though Athabasca is believed to be the most recent major volcanic eruption on Mars, it still happened a long time ago, 600 million years. This fact is confirmed by the white splotched craters on top of the lava. Scientists have in fact estimated the age by counting the number of craters, since they have a rough idea of the impact rate for Mars over the last few billion years or so, based on crater counts on the Moon.
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