For some time now, there has been broad agreement among astronomers that the distance from the earth to the moon is not a physical "constant," that it has been gradually increasing. The generally accepted rate of increase, however, has been so slow that during most of recorded geologic time, the moon could not have affected earth processes any more significantly than it does today.

Recent work by Munk of Scripps and MacDonald of NASA reopens the debate on the history of the earth-moon system. They have shown that earlier conclusions by Jeffreys and others may be in error. Extrapolation backward into geologic time, if a drastically increased rate of change in the distance to the moon is assumed, suggests a moon close enough to earth to produce major effects on geologic processes, perhaps of catastrophic proportions.

Investigations by Ewing in the South Atlantic, using seismic reflection techniques, have indicated a widespread surface below the present sea floor. Tentative interpretations of this surface by Heezen and others suggest it may represent a major event in the history of ocean sedimentation, perhaps a world-wide fall of volcanic ash or even cosmic dust.

The correlation of possible ancient earth-moon positions with known events in the geologic time table, as well as with such "uniformitarianistic" phenomena as tidal action, is thought-provoking. Recent research appears to be significant enough to warrant a closer coupling between historical geology and the "new" astronomy.

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