MISSED THEMIS IMAGEs: Catching up here, with Olympus Mons lava flows....

At first glance, this image of lava flows around the large scarp of Olympus Mons shows little contrast in surface materials due to dust cover, but a closer look reveals textures characteristic of the variable surface roughness associated with different lava flows in this region. The lobate edges of the flows are distinctive, and permit the discrimination of many overlapping individual flows. On small scales, the surfaces of some flows look wrinkly and ropy, indicating a relatively fluid type of lava flow referred to as pahoehoe. Other surfaces appear more rough and broken, and might be referred to as a'a flows, which have higher viscosities and effusion rates compared to pahoehoe flows. The surface textures of lava flows can thus sometimes be used for comparative purposes to infer lava viscosity and effusion rates. There is also a bright streak in the wind shadow of the impact crater in the lower left of the image where dust that settles onto the surface is not easily scoured away.

...and Semeykin Crater:

This is an image within Semeykin Crater, which is located in the Martian northern hemisphere. This location is at the edge of the planetary dichotomy, a boundary between the heavily cratered and older southern highlands and the lightly cratered northern lowlands. This boundary is marked by remnants, or 'islands', of highland terrain standing out within the northern lowlands. It is uncertain how this dichotomy formed, but the interior of this crater has been resurfaced with the smoother, younger terrain. Much of the older remnants appear softened. This may be due to past or present subsurface ice that can deform the terrain. Dark sand is also visible in the right hand side of the image.