Nilokeras Scopulus is a longescarpment (cliff) in the northern hemisphere of the planetMars. It is located along the southeastern boundary of theTempe Terra plateau and forms the northern valley wall (wallrock boundary) of the downstream portion of the immenseKasei Vallesoutflow channel system. The escarpment is 765 km long[citation needed][1] and ranges from 1 to a little over 2 km (3300–6600 ft) in height.[2]
For most of its length, Nilokeras Scopulus lies between lat. 31° and 32° N. It trends west-east, extending from approximately long. 297° to 309° E.[1] The escarpment curves northward at the eastern edge of Tempe Terra where the northern segment of Kasei Vallesdebouches intoChryse and southwesternAcidalia Planitiae.
Nilokeras, which is Greek for "horn of theNile," was the name given by astronomerE. M. Antoniadi in 1930 to a telescopicalbedo feature andcanal centered at lat. 30° N., long. 55° W. (SeeList of Martian canals.)Scopulus is adescriptor term used in planetary geology for an irregular escarpment or cliff. TheInternational Astronomical Union (IAU) formally adopted the name Nilokeras Scopulus in 1976.[1]Scopulus is the Latin term for "crag" or cliff.
Ingeomorphology, an escarpment (usually shortened to scarp) is any steep, abrupt slope or cliff along the margin of aplateau,terrace, or othertopographic bench. A scarp may be formed bytectonic,erosional, ordepositional processes.[3] The term carries no implication of geologic origin.
Nilokeras Scopulus likely formed from a combination of faulting and erosion from flood waters that formed Kasei Valles. Recent geologic mapping of the Kasei Valles region[4][5] indicates that the west-to-east flow of the Kasei Valles floods followed the existingstructural trend ofrift valleys in southern Tempe Terra. Thus, the proto-Nilokeras Scopulus was probably an east-west oriented fault scarp or fracture zone (or zone of weakness[6]) that was eroded and further downcut by at least one (and possibly two) episodes of early catastrophic flooding from the northernTharsis region. (Seeoutflow channels.) These floods occurred inHesperian time between about 3.6 and 3.4 billion years ago (Gya).
After initial flooding, the northern Kasei valley was covered by extensive late Hesperian-aged basaltic lava flows fromTharsis. Two final episode of flooding from theEchus Chasma region to the south occurred in Kasei Valles duringAmazonian times (<1.8 Gya). The later floods carved the channels south of Nilokeras Scopulus and may not have strongly influenced development of the scarp.
During the course of its history, Nilokeras Scopulus has been subjected to glacial/periglacial processes and modified bygroundwater sapping, slumping, collapse, and othermass wasting processes. Rocks making up the scarp face are Noachian or Early Hesperian in age (>3.6 Gya). They probably consist of ancientimpact breccias and volcanic materials. Layered bedrock is visible at the top of the escarpment in some medium and high resolution spacecraft images, but the scarp face is largely covered bytalus aprons and dust.
