At the base of the Olympus... (EDM - Saturated Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)

The bottom right part of the cutout has a much flatter and smoother surface. These are younger lava flows that have buried the lower part of the volcano. When lava flows form vast smooth sheets, they are called "flood" lavas.

In the bottom of the cutout, the flood lavas have odd, wiggly looking plateaus. These are parts of the lava crust that were lifted up when more liquid lava was injected into the middle of the slowly solidifying lava flow.
This process is called "inflation" and is seen on many lava flows on Earth. These younger lava flows are cut by two different sets of faults. One makes the branching valley in the flood lavas and the other creates the sinuous ridge and valley along the edge of the Olympus Mons lava flows.
Lower resolution images that cover a broader area suggest that the sinuous fault is an old buried structure that has been more recently reactivated.