Sachgebiete

Beschreibung:

66 S., Fotos/Karte, 28cm Gewebe

Bemerkung:

Zustand: Privateinband einer wissenschaftlichen Arbeit, Namenseintrag eines der Prüfer, mit Originalfotos, diese teils mit überlappenden transparenten Folien, Karte in Laste im hinteren Vorsatz. Sehr gut --- Inhalt: englischer Text, geologische Prüfungsarbeit. "In 1968, Charles Marsh Woodruff, Jr., did his thesis research on the Howell Structure to (1) determine the geographic and stratigraphic limits of the deformed rocks of the structure and to (2) re-assess its age. The presence of breccias or a dip greater than 20° was used to define the perimeter of the feature at six control points. Howell was found to be a slightly irregular ellipse that trended along a NE-SW axis, approximately 8200 feet (2500 m) in length by 6000 feet (1830 m) in width. The structure?s age was tightly constrained to the Upper-Devonian between the disturbed basal sand member and the undisturbed upper shale member of the Chattanooga Shale. One unique outcrop was discovered in the hills on the northeast boundary of the structure that was described as a mixture of deformed sand, chert, sulfides and carbonaceous material of Silurian and Devonian age. Quartz grains in thin sections made from this outcrop displayed lineation (some with two sets of cleavage), fragmentation, micro-brecciation, and flow features. One quartz grain had been granulated and reindurated, keeping its original shape. There were no petrography studies of other strata. (The thin sections did not survive the passage of 35 years of time and are lost for further study.) In addition, two possible shatter cones were reported. Woodruff oncluded that the Howell Structure is probably an impact crater, but conceded that the evidence is not conclusive. The thesis was not published." [Lunar and Planetary Science XXXV (2004)] KK-PS24-1