Farouk El-Baz

Document Type

Article

Publication Date

1980

Abstract

Sketches made by G. K. Gilbert and based on telescopic observations of the Moon look amazingly similar to photographs obtained 75 yr later by spacecraft. He was very successful In 'orrelating lunar surface features with counterparts on Earth. His obscrvations and experiments led him to the conclusion that most lunar craters are the product of impact. After establishing this, he studied the Coon (Meteor) Crater of Arizona. He did not have as much success applying what he had lcarned from the Moon to the terrestrial case. He conducted a topographic study of the crater to check whether there was an added volume due to the incoming jojectile. An overestimation of the size of the metcorite and ict of the possibility of its fusion, evaporation. and ejection forced him to rule out an impact origin for this crater. In his observations on lunar featurcs. Gilbert had expressed the basic elements of a lunar stratigraphic system. His discussion of crater rays, and particularly of the "sculpture"" that surrounds the mbriuim basin, greatly influenced the thinking of lunar geologists our day. Coupled vith his ecognition of the importance or rrater density and overlap relationships. he can be casily onsıdered ie father of lunar stratigraphy Today there is a crater the Moon bearing the name of Gilbert in commemoration of his many contributions to geology At the end of the nineteenth century, uniformitarianism had gained many supporters, Thus, the Earth was vicwed as a product of slow and continuous change that could be easily explained in terms of the same processes that are observable today. The Moon "Onsidered along sımilar lines of thought. with the conse- quence that most of its surface features were interpreted to be the esult ofendogenetic processes. Gradual and prolonged volcanism ras credited with the formation of the lunar surface fcatures, craters- which constitute the most predominant of lunar landforms.

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