248 FRANK LEVERET T 



ville and Bloomington ice advances. The Shelbyville sheet had 

 apparently become channeled by streams prior to the Bloom- 

 ington substage of glaciation to nearly as marked a degree as 

 the channeling below the level of the loess effected in the 

 Peorian stage of deglaciation. There is also a marked increase 

 in the stream gradient, the Bloomington drift sheet being 

 accompanied by a much more vigorous gravel outwash than that 

 which accompanies the Shelbyville sheet. In the writer's 

 opinion it is questionable if the interval between the Iowan and 

 early Wisconsin invasions covers more than a comparatively small 

 part of the time occupied by the intervals between the Iowan 

 and Illinoian, and between the Illinoian and Kansan. The 

 union of the several lines of evidence just cited would seem to 

 support the view that it is longer than interglacial substages of 

 the Wisconsin. The view of a brief interval between the Iowan 

 and Wisconsin meets a strong objection, however, in the sup- 

 posed attendant deposits at Toronto. 



Turning to the Toronto formation it is found that a fossilif- 

 erous silt occupying a horizon between bowldery glacial clays 

 has a fauna and flora which denote a climate fully as mild as at 

 present characterizes that region. 1 In discussing this formation 

 Dr. A. P. Coleman remarks that unless the Labrador gathering 

 ground is shown to have stood much higher than at present it 

 can scarcely be supposed that a widespread sheet of ice was 

 maintained there, while oaks and maples and pawpaws flourished 

 on the land and Mississippi unios in the waters within 400 to 

 500 miles to the southwest. In the absence of any evidence of 

 such an uplift he concludes that the ice fields were completely 

 melted during this interglacial epoch. Professor D. P. Penhallow 

 remarks that the arborescent forms of vegetation in these inter- 

 glacial beds are of species such as may now be found in the 

 same region. 



r See descriptions by Dr. A. P. Coleman and Professor D. P. Penhallow in 

 American Geologist, Vol. XIII, Feb. 1894, pp. 85-95. See also additional interpre- 

 tation by Dr. Coleman, in Jour. Geol., Vol. Ill, pp. 274, 622-645. 



For description of fossiliferous beds at Scarborough Heights and other localities 

 near Toronto, by Dr. G. J. Hinde, see Journal of the Canadian Institute, April 1877. 



