This channel on Mars? Water made it. Open this thread to see how it works.
See these channels? The ones on the left were made by lava, while the ones on the right were made by water. The channels made by water look more like the channel on Mars than the lava does.
In our stream table experiments, the differences between water-formed channels and lava-formed channels were clearly demonstrated. In a channel formed by water, branches tend to stick out of the original channel. If you take a close look, that's what is happening here.
Since the two landforms look so similar, this should prove that they were created through the same or a similar geologic process.
Now, this couldn't have been lava because in the stream table with hot wax, it was shown that the "lava" flowed in one channel instead of branching out like the water-formed channel, and also the one on Mars.
In conclusion, this channel on Mars wasn't formed by lava, but by water! Convinced yet?