Information Circular 70
	Summary of isotopic age determinations in Pennsylvania by Lapham, D. M., and Root, S. I. 1971
Suggested Citation:	Lapham, D. M., and Root, S. I., 1971, Summary of isotopic age determinations in Pennsylvania: Pennsylvania Geological Survey, 4th ser., Information Circular 70, 29 p. [Available online.]
Description:	Summary report of radiometric age determinations (excluding carbon-14 ages) of Pennsylvania rocks and minerals made through 1969. This includes data published by individual researchers and 12 previously unpublished isotopic dates determined for the Pennsylvania Geological Survey. Isotopic ages are summarized in the report by physiographic region. Major text topics also include techniques of radiometric analysis, geological limitations of radiometric dating, and a general discussion that draws conclusions about the age of notable tectonic events.
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