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Processes of lunar crater degradation - Changes in style with geologic timeRelative age schemes of crater degradation are calibrated to radiometric dates obtained from lunar samples, changes in morphologic features are analyzed, and the style and rate of lunar surface degradation processes are modeled in relation to lunar geologic time. A comparison of radiometric age scales and the relative degradation of morphologic features for craters larger than about 5 km in diameter shows that crater degradation can be divided into two periods: Period I, prior to about 3.9 billion years ago and characterized by a high meteoritic influx rate and the formation of large multiringed basins, and Period II, from about 3.9 billion years ago to the present and characterized by a much lower influx rate and a lack of large multiringed basins. Diagnostic features for determining the relative ages of craters are described, and crater modification processes are considered, including primary impacts, lateral sedimentation, proximity weathering, landslides, and tectonism. It is suggested that the fundamental degradation of early Martian craters may be associated with erosional and depositional processes related to the intense bombardment characteristics of Period I.
Document ID
19750050844
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Head, J. W.
(Brown University Providence, R.I., United States)
Date Acquired
August 8, 2013
Publication Date
March 1, 1975
Publication Information
Publication: The Moon
Volume: 12
Subject Category
Lunar And Planetary Exploration
Accession Number
75A34916
Funding Number(s)
CONTRACT_GRANT: NGR-40-002-116
Distribution Limits
Public
Copyright
Other

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