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Don E. Wilhelms

Publications and source records attributed to Don E. Wilhelms.

7 recordsLinked to original sources
USGS2007

Geologic Map of Part of the Western Hellas Planitia, Mars

Introduction Rock units were deposited on Mars by meteorite impact, volcanism, wind, flowing water, standing water, and ice, acting separately or in concert. Hellas Planitia, the deepest tract on Mars, is a broad depression lying within the high-rimmed, approximately 2,300-km-wide Hellas impact basin. The basin and the planitia are centered about 250 km east of the southeast corner of the map area. Like other stratigraphy-based planetary mapping (Wilhelms, 1990), we suggest the most likely origins for age relations and morphologies visible in the map area.

Scientific Investigations Map↗
USGS1973

Stratigraphic studies: Part D: geologic map of the northern Crisium region

Apollo 17 metric photographs (fig. 29-26) provide the best available coverage for geologic interpretation of northern Mare Crisium and the northern Crisium basin. The area was covered previously by low-resolution telescopic and Lunar Orbiter IV photographs and by oblique, high-illumination, or low-resolution photographs from earlier Apollo missions. One region in particular, between Alhazen Crater and longitude 66° E, had previously been covered very poorly. The Apollo 17 photographs provide excellent monoscopic (fig. 29-26) as well as stereoscopic viewing because of the favorably low Sun illuminations (15° to 49°). These new photographic data allow the geology of the basin, the mare, and other nearby terrains to be reevaluated. This reexamination together with data from continuing Moon-wide photogeologic studies and analyses of returned rocks from Apollo landing sites, has produced a simple evolutionary picture of the region, expressed by fewer map units and explained by fewer basic processes than previously thought necessary (refs. 29-35 and 29-45 to 29-48).

Book chapter↗
USGS1972

Orbital-science investigation: Part J: preliminary geologic map of the region around the candidate Proclus Apollo landing site

The Proclus Crater region was mapped to test the value, for photogeologic mapping purposes, of Apollo 15 metric photographs and to estimate the scientific value of the area as a potential landing site. A metric photographic frame (fig. 25-67) serves as a base for a map of the region around the Proclus Crater (fig. 25-68), and adjacent frames were overlapped with the base frame to provide stereographic images. The excellent stereocoverage allows easy simultaneous observation of topography and albedo. The large forward overlap and the extensive areal photographic coverage provide the best photogeologic data available to date. Brief study has already refined earlier interpretations of the area (refs. 25-7 and 25-32). Although volcanic units have been shown to be extensive in this region, mass wasting apparently has been more important than volcanism in shaping terra landforms.

Book chapter↗
USGS1972

Photogeology: Part F: reinterpretations of the northern Nectaris Basin

Geologic units of the Nectaris Basin rim have been interpreted as partly impact and partly volcanic in origin (refs. 29-4, 29-21, 29-35, 29-38, and 29-39). An exclusively volcanic origin was proposed for the material in the vicinity of the Apollo 16 landing site, slightly northwest of the Nectaris Basin (ref. 29-36). In view of the dominance of breccia and the paucity of volcanic material in the returned Apollo 16 samples, it now seems appropriate to reevaluate this part of the Moon to test whether the geology of the units mapped to date can be reconciled with an impact origin. Therefore, photogeologic analysis was attempted on a strip of Apollo 16 metric photographs; the superior quality and stereographic properties of the photography permit this reevaluation (fig. 29-32). Geologic contacts, as redrawn, closely resemble those of the earlier maps cited, but some differences result because of improved photographic quality and a conscious attempt to test fully the impact hypothesis.

Book chapter↗