ISSN:
1573-0794
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Geologie und Paläontologie
,
Physik
Notizen:
Abstract Nine Orbiter 3 high-resolution photographs were examined at three sites for distributions of boulders around craters ⩾ 110 m in diameter; three kinds of distributions were noted. Some had boulders inside and far outside (designatedα), others had boulders only inside or on their ramparts (β), and some had no detectable boulders (γ). Additionally, shapes or morphologies of craters were classified according to their resemblance to one of three Jaffe models (1965); a third classification involved the depth of particulate overlay (Jaffe, 1965). Crater morphologies were classified (A) if they were relatively shallow with sharp, raised rims, (B) if they were rimless and shallow, and (C) if they were relatively deep and had low, broad rims. The data suggested that there were strong relationships between crater types and boulder distributions in which, generally, A-type was related to theα-distribution, B-type toγ-distribution, and C-type toβ-distribution. Plots of numbers of craters of each crater type and each kind of boulder distribution versus steps of overlay for each site and for the totality of craters considered indicated that neither boulder distribution nor crater type represented orderly progression of age or erosional evolution. The apparent overlays for the A's and C's and for theα's andβ's were similar, implying similar ages or stages of erosion. It is suggested that they represent two kinds of primary craters and that the Aα's are of impact origin while the Cβ's are of volcanic origin. The Bγ's probably represent later stages of erosion of the C's and possibly of some A's.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00561907
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