326 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1952 



NOTE ON THE CARBON-14 TESTS 



On April 15, 1953, after the manuscript of the foregoing article 

 was completed, a report was received from Dr. W. F. Libby, Institute 

 of Nuclear Studies, University of Chicago, concerning an examination 

 by the carbon-14 method of grasshoppers collected in 1952 by Dr. 

 Irving Friedman in the deeper layers of the "old" glacier. Dr. Libby's 

 conclusions are that the age may be most appropriately given as 

 45 ±300 years and that the limits of error would be 45 ±600 years. 

 This indicates that these grasshoppers are quite modern, and it seems 

 definite that they are younger than 600 years. Unfortunately, the 

 samples examined have been rather small, and the standard errors 

 involved by this method are sufficient to make an age estimate of such 

 relatively recent material quite broad. The results appear to rule 

 out the possibility that the grasshopper deposits are extremely ancient, 

 and they add weight to the view that the Beartooth glaciers are of 

 relatively recent origin. — A. B. G. 



