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Marcus, A. H.

Publications and source records attributed to Marcus, A. H..

Statistical models of lunar rocks and regolith

The mathematical, statistical, and computational approaches used in the investigation of the interrelationship of lunar fragmental material, regolith, lunar rocks, and lunar craters are described. The first two phases of the work explored the sensitivity of the production model of fragmental material to mathematical assumptions, and then completed earlier studies on the survival of lunar surface rocks with respect to competing processes. The third phase combined earlier work into a detailed statistical analysis and probabilistic model of regolith formation by lithologically distinct layers, interpreted as modified crater ejecta blankets. The fourth phase of the work dealt with problems encountered in combining the results of the entire project into a comprehensive, multipurpose computer simulation model for the craters and regolith. Highlights of each phase of research are given.

Marcus, A. H.↗

Production of lunar fragmental material by meteoroid impact.

The rate of production of new fragmental lunar surface material is derived theoretically on the hypothesis that such material is excavated from a bedrock layer by meteoroid impacts. An overlaying regolith effectively shields the bedrock layer from small impacts, reducing the production rate of centimeter-sized and smaller blocks by a large factor. Logarithmic production rate curves for centimeter to motor-sized blocks are nonlinear for any regolith from centimeters to tens of meters in thickness, with small blocks relatively much less frequent for thicker (older) regoliths, suggesting the possibility of a statistical reverse bedding. Modest variations in the exponents of scaling laws for crater depth-diameter ratio and maximum block-diameter to crater diameter ratio are shown to have significant effects on the production rates. The production rate increases slowly with increasing size of the largest crater affecting the region.

Marcus, A. H.↗

On the definition of crater saturation diameter

A theoretical model is developed for determining the diameter D sub p such that the density of lunar craters exceeding D sub p constitutes a specified proportion p of the maximum number that could be observed on a crater-saturated surface. It is shown that this diameter is sensitive to the value of the exponent in the fresh crater size distribution, and is much more informative than usual log-log plot intercept definition of satureation diameter.

Marcus, A. H.↗

Martian craters - Number density.

Incremental frequency distribution of Martian craters larger than 20 km found to follow inverse square law with density equal to lunar continents, noting Martian surface age

Marcus, A. H.↗