104 PROCEEDINGS OF THE ACADEMY OF [1894. 



disintegrating streamlets which made it at the same time nearly filled 

 it with the residuum of their own erosion ? If it was older than the 

 ice sheet, why w^ere no tertiary fossils associated with the quater- 

 nary ? None of the bones that protrude from the bleak gorges 

 in the bad lauds of Texas to frighten Indians have ever been 

 found in subterranean rock hollows. We found none of these in 

 or below this clay in Hartman's Cave. Had they never lain 

 there, or, coming in like their quaternary succesi^ors, had they been 

 washed out, or, us Prof. Cope suggests, had the whole tertiary fossil- 

 bearing end of the cave been eroded away iu the lapse of time ? How- 

 ever this may be, if we are right, the clay in Hartman's Cave marks 

 with the precision of a pointing clock hand, the hour of the glacier in 

 the world's history. What is under the clay comes before what is 

 over it, after the ice. 



If the ice made the clay we must go back, not to any event since 

 the clay (post glacial) or any event during the clay-making (glacial) 

 but to some event before ( preglacial ) to find a force, whether of cave 

 washing or cave erosion, that could have swept this cave clean of the 

 fossil remains of creatures that lived before the quaternary. 



