MASTODONS, MAMMOTHS AND OTHER PLEISTOCENE MAMMALS 69 



glaciated territory, in this case reaching to central Pennsylvania. 

 But the deep Ontarian valley (present Ontario basin) lying athwart 

 the trend of ice movement introduced important modifying factors, 

 and but few of the mammoths were carried far to the south of Lake 

 Iroquois by the glacier. 



The remains of most of the Canadian animals that were over- 

 whelmed by the glacial snows were incorporated in the lower, or 

 ground-contact ice of the southward-moving sector of the Quebec 

 (Labradorian) ice cap. This deepest portion of the ice sheet was 

 pushed into the deep Ontarian valley and becoming stagnant be- 

 cause of its position and also of its load of detritus, it served dur- 

 ing all the duration of the Quebec glacier as a bridge over which 

 the upper ice, by a shearing flow, passed on south over New York. 

 This element of glacier mechanics is fundamental to the present 

 explanation of the peculiar distribution of the E 1 e p h a s remains 

 and is believed to describe the behavior of the continental glacier 

 toward deep and capacious valleys, not only those transverse to the 

 ice flow but also longitudinal valleys, especially when these decline 

 toward the transgressing ice sheet, like the Finger Lakes valleys. 



During the life of the Quebec glacier, the captured mammoth 

 remains lay in refrigeration in the Ontarian valley, until, with the 

 waning of the glacier, the frontal melting reached their position. 

 Then some of them were lifted in floating ice on the waters of Lake 

 Iroquois and were rafted to the south shore. Of these, some were 

 buried and preserved in the deposits laid in the rising waters on 

 the south shore, and of these a few have been discovered. 



The above explanation and glacial history assumes only a single 

 ice invasion, which is thought to be true for New York and New 

 England. If dual glaciation is claimed, as is the case in the Toronto 

 region where proboscidian remains are found in interglacial deposits, 

 the mechanical conditions would be duplicated in essential factors, 

 but it would be necessary to repopulate southern Canada with the 

 E 1 e p h a s fauna, as the second ice advance would remove the 

 fossils left by the first ice recession. 



The history need not be complicated by postulating deep-ponded 

 waters in the Ontarian valley during the earliest transgression by 

 the ice (a " preglacial Iroquois") because the latter found a great 

 river valley of free drainage southward. 



The entrapping of the mammoth remains in the deep valley of 

 the lower ice, their release by flotation in the ice rafts of the frontal 

 waters and the rafting of the fossils to the south shore of Lake 

 Iroquois, appear to afford a reasonable explanation of the peculiar 

 relation of the discovered fossils. 



