[null and void]

A trick of light and shadow. the image was illuminated from the bottom, a very unnatural way to view things. Rotate it 180° and the illusory ridge turns into a valley.

[going hot]

Must be years of marination in etoh, but I cannot get the monitor in any degree of rotation that reverses the bulge.

Regardless, how did the water get there, and where is it?

Assuming it was water.

[going hot]

Also, most river beds start with a trickle, then join others to form larger and larger channels.

Thus there is feathering at the smaller branches upstream on dry beds.

These beds, and their tribs have rounded ends, more like a flow going in the opposite direction, then cooling off, similar to ice or lava flows on this planet.

At least with the depiction above.