Mars: Fretted and chaotic terrains

Abstract

Fretted terrain is but one of a variety of lowland terrains on the Martian surface that, like members of an isomorphous series, have some characteristics in common and are shaped by some of the same genetic processes. These terrains are artificially separated to facilitate handling (Table 1). At one extremity are the south polar pits described elsewhere [Sharp, 1973]; at the other are the huge equatorial troughs.Fretted terrain is characterized by smooth, flat, lowland areas separated from a cratered upland by abrupt escarpments of complex planimetric configuration and a maximum estimated height approaching 1-2 km (Figure 1). It is the product of some unusual erosive or

Chronology, Eruption Duration, and Atmospheric Contribution of the Martian Volcano Apollinaris Patera

“…This unit roughly corresponds to the Hcht (chaotic material unit) of Greeley and Guest (1987) and Scott and Dohm (in press), which are interpreted to be erosional remnants of a heavily modified preexisting terrain. Chaotic material, or terrain, is generally accepted to be the result of removal of large volumes of ground ice from within the interstices of the original frozen ground (Sharp 1973;Carr and Schaber 1977). The contact between the chaotic material (cht) and the western flanks (m) of Apollinaris Patera indicate that this process continued after the main edifice building eruptions as the lower western flank is chaotically disrupted (Figs.…”

“…Additionally, materials that we interpret to be associated with the formation of the fan (f) overlie the Unit m is the main edifice, unit cfl is the outer caldera, unit f is the fan material, and cf2 is the inner caldera all of which compose the volcanic products of Apollinaris Patera. Unit cht is a broad area of chaotic terrain that is generally believed to be the result of the removal of large amounts of ground waterlice (Sharp 1973, Carr and Schaber 1977, Greeley and Guest 1987. Note that the chaotic terrain (cht) includes disrupted material of Apollinaris Patera which is not mapped separately for the purposes of this work.…”

Radar evidence for ice in lobate debris aprons in the mid‐northern latitudes of Mars

“…Deuteronilus Mensae (Figure 1; 40 -51°N, 14 -35°E), part of the dichotomy boundary ''fretted terrain'' [Sharp, 1973] contains a high concentration of LDAs [Squyres, 1979;Squyres and Carr, 1986;Hauber et al, 2008] that occur at the bases of scarps of mesas, knobs, craters and valley walls [Chuang and Crown, 2009]. Relief of the adjacent scarps is generally 1 -2 km, and most of the LDAs themselves have 300-800 m of relief relative to the surrounding valley floors.…”

Earth Science Field Work: Role And Status

“…I have been fortunate to participate as a colleague in modern geochemical stable isotope research (Epstein & Sharp 1959) and in planetary science projects (Sharp 1973), largely because as a classical, old-time field geologist, I could bring something useful to the investigations.…”