Search USGS⌕ Search

Geology topics

R. E. Eggleton

Publications and source records attributed to R. E. Eggleton.

9 recordsLinked to original sources
USGS1973

Geologic map of the Rumker Quadrangle of the Moon

The Rumker quadrangle, in the northwest quadrant of the Moon, is adjacent to the western rim of the multi-ring Imbrium basin and to Sinus Iridum , a large (220 km diameter) mare-filled crater. Both of these great depressions were probably formed by impa c t, as indicated here and elsewhere on the Moon by the characteri stic form, distribution, and texture of surrounding materials and structures. The Imbrium b asin and Iridum crater were filled by mare mat erials during the Imbrain and Eratosthenian Periods. In this quadrangle, the widespread ejecta blanke t of the Imbrium basin, as well as the basin’s concentric ridges and mountain rings, has largely been buried by terra materials of mixed origin and by ejecta from Iridum and numerous smaller impact craters. These materials , together with some terra units of probable volcanic origin, make up the highland terrain. Mare materials of Oceanus Procellarum cover part of t his westward-sloping highland shelf that separate it from the Rumker Hills, an isolated plateau surrounded by the mare. No visible discontinuity distinguishes mare material of Oceanus Procella rum from those in the Imbrium basin, both of which contain several units having similar albedo and color. Parts of the mare are very dark and smooth and appear relatively young, and parts of the terra contain many diverse landforms of Imbrian and younger age that appear to be volcanic . This region may therefore have been more active internally during late stages of lunar history than many others on the near side.

IMAP↗
USGS1973

Apollo lunar sounder experiment

The scientific objectives of the Apollo lunar sounder experiment (ALSE) are (1) mapping of subsurface electrical conductivity structure to infer geological structure, (2) surface profiling to determine lunar topographic variations, (3) surface imaging, and (4) measuring galactic electromagnetic radiation in the lunar environment. The ALSE was a three-frequency, wide-band, coherent radar system operated from lunar orbit during the Apollo 17 mission.

Book chapter↗
USGS1972

Preliminary geologic investigation of the Apollo 16 landing site

The Apollo 16 landing site in the lunar central highlands encompassed terra plains and adjacent mountainous areas of hilly and furrowed terra. These morphologic units, representing important terrane types in the lunar highlands, had been interpreted as volcanic on most premission geologic maps. However, it became apparent during the mission that there are indeed few or no volcanic rocks or landforms at the site but rather that the area is underlain by a wide variety of impact-generated breccias.

Book chapter↗
USGS1972

Photogeology: Part B: Cayley Formation interpreted as basin ejecta

The discovery that samples returned from the Cayley Formation at the Apollo 16 landing site consist mainly of nonvolcanic breccias (secs. 6 and 7 of this report) suggests that the hypothesis in which light plains-forming materials may be ejecta from multi-ring basins should be reevaluated (refs 29-15 to 29-17). Improved information on the morphology and distribution of the Cayley Formation, provided by Apollo 16 orbital photography, leads to a concept in which the Cayley Formation was deposited as fluidized debris that traveled beyond the presently recognizable extent of the Imbrium Basin ejecta. An elaboration of this genetic model is in preparation; the description, a summary of the model, and its implications are presented in this subsection.

Book chapter↗
USGS1970

Lunar radar mapping: Correlation between radar reflectivity and stratigraphy in north-western mare imbrium

DELAY-DOPPLER radar maps of the Moon obtained with the 430 MHz (70 cm wavelength) radar of the Arecibo Ionospheric Observatory in Puerto Rico (Thompson, unpublished) are at present being studied to correlate geological information with the radar reflexion characteristics of the lunar surface. Preliminary evaluation of the radar data for the Sinus Iridum quadrangle (32°–48° N; 14°–38° W) has revealed that the lowest values of radar reflectivity are closely correlated with the mare materials of lowest albedo mapped by Schaber 1 as of most recent volcanic origin. These radar data were obtained with a surface resolution of 50 to 100 km 2 on January 24 and April 17, 1967. A detailed account of the delay-doppler radar mapping technique can be found in unpublished reports by Thompson.

Nature↗
USGS1961

Paper A: Terrestrial features of impact origin

Craters made by meteorites striking the earth are discussed, with attention given to geological evidence for discriminating them from craters formed by other structural processes. The major known meteorite craters are briefly described, as well as other features that are considered probable or possible meteorite craters on the basis of less conclusive evidence. Separate tabulations are given of (1) topographic features either known to be meteorite craters, or considered as possible meteorite craters through lack of conclusive evidence to the contrary, and (2) topographic features once considered to be possible meteorite impact craters, but which are now believed to be of other origin.

Conference Paper↗