CRITERIA REQUISITE TO A GLACIAL AGE 85 



be relegated to the category of doubt, unless the special features 

 of the cases themselves give them convincing force. These 

 classes are: (i) the valley trains of gravel, sand, and silt, 

 except where immediately connected with moraines or possessed 

 of special features that demonstrate their strict contemporaneity 

 with an ice invasion ; and (2) all secondary or disturbed deposits, 

 and all recomposition deposits. 



All deposits connected genetically with river channels, with 

 eroded bottoms or bluffs formed in valley trains of gravel, are 

 to be entirely excluded from serious consideratioji. They not only do 

 not help on the cause of glacial man in America — if one may 

 speak as an advocate — but they hinder it by throwing doubt 

 over the whole evidence with which they are associated. 



The important question of man's antiquity in America will, in 

 my judgment, be helped on to solution most effectually by freely 

 relegating to the shelves all doubtful evidence and by turning 

 search toward the sources whence reliable evidence is most likely 

 to be forthcoming, and by giving to that search the highest pos- 

 sible credentials of scientific trustworthiness. A few really 

 good cases standing by themselves in their own good company 

 would be decisive ; a thousand weak ones can only leave the 

 question in doubt, 



T. C. Chamberlin. 



