1898] Pleistocene Geology in Ottawa Valley. 213 



it and deposited them wherever it chanced to be when the ice 

 ceased to move forward. In connection with this it is urged 

 that blocks of stone, entering the bottom of the glacier under 

 certain conditions, gradually rise to the surface and in this way 

 often reach a height far above their original position. It may 

 be remarked that more or less serious objections have been 

 raised against all these explanations. 



LEDA CLAY. 



The next formation in ascending order is the Leda clay, 

 which is common in all the tower levels of the Ottawa Valley, 

 where it forms broad stretches of level country. It is a bluish- 

 gray clay, somewhat unctuous, and when dry becomes very hard 

 and cracks into square or oblong shaped blocks. In Ross and 

 Bromley townships there are large areas covered with this clay. In 

 one place in Ross is a plain five miles across which extends length- 

 wise for a much greater distance, The approximate height of 

 these plains is from four hundred to four hundred and fifty feet. 

 Though the roads traversed passed over many miles of this 

 formation the only fossil found was a fragment of a shell which 

 was too small to be identified. 



For a description of this deposit below the City of Ottawa, 

 I quote the following, " Along the south bank of the Ottawa 

 River from the city of Ottawa to Hawkesbury, and again from 

 Point Fortune to its junction with the St. Lawrence the lower 

 clay is seen in binks of from twenty to forty feet in height. . . . 

 The greatest breadth of the level clay surface which has been 

 observed here is in the township of L'Orignal, where it extends 

 about fifteen miles back from the river. . . . On the north side 

 of the Ottawa, from Hull to Isle Jesus, the clay often covers a 

 considerable breadth between the river and the Laurentian Hills 

 and extends among these for several miles up the larger tribu- 

 taries."* Mr. A. E. Barlow states that this clay is abundant at 



* Geology of Canada, p. 916. 



