The Kachina Chasmata are the longest

canyon A canyon (from ; archaic British English spelling: ''cañon''), or gorge, is a deep cleft between escarpments or cliffs resulting from weathering and the erosion, erosive activity of a river over geologic time scales. Rivers have a natural tenden ...

or system of canyons on the surface of the Uranian moon Ariel. The name comes from a spirit in Hopi mythology. The 622 km long and 50 km wide chasmata arise from a system of normal faults running from the north-west to south-east. The faults bound down-dropped

crustal blocks Fault blocks are very large blocks of rock, sometimes hundreds of kilometres in extent, created by tectonic and localized stresses in Earth's crust. Large areas of bedrock are broken up into blocks by faults. Blocks are characterized by relat ...

forming structures called

graben In geology, a graben () is a depressed block of the crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic contex ...

. The canyons cut the cratered terrain, which means that they were formed at a relatively late stage of the moon's evolution, when the interior of Ariel expanded and its ice crust cracked as a result. The floor of the canyons is not visible on the images obtained by the '' Voyager 2'' spacecraft in January 1986; thus, whether it is covered by smooth plains like the floors of other Arielian graben is currently unknown. During the ''Voyager 2'' flyby in 1986 the northern hemisphere of Ariel was not illuminated by the Sun because the spacecraft arrived during a southern solstice on Uranus. Nevertheless, because it was still illuminated by light reflected from Uranus, scientists using advanced processing methods were able to detect some details in the dark hemisphere. These analyses revealed a continuation of the Kachina Chasmata into the dark hemisphere, possibly as far as to the opposite limb. As the total length of the feature appears to be 1800–2200 km, it may be comparable to Ithaca Chasma on Tethys.

References

Citations Sources * * * * * * Ariel (moon) Surface features of Uranian moons {{crater-stub