The surface and geologic history of Uranus’ icy satellite Ariel is surprisingly complex compared to other icy satellites of similar size. Volcanism, faulting, and impact craters seen in this view of the southern hemisphere have essentially reshaped Ariel's surface since its formation. The most prominent topographic features are wide steep-walled canyons or chasmata 3–5 kilometers deep (center and upper left). The youngest of these, Sylph Chasma, crosses the center of view and has a raised rim that stands above the surrounding topography. Tilted crustal blocks are visible at upper left and upper right. Several patches of smooth plains (at bottom) up to 200 kilometers across occur on Ariel. These plains appear to be lava flows and may be composed of ammonia-water mixtures. The floors of the canyons also appear to be partially filled with viscous lava plains of similar composition. Tidal heating may have been responsible for the tectonic and volcanic activity observed on Ariel, which measures only 1160 kilometers across.
2 images 26843.38, 26845.33.)