THE SUCCKSSION OF DEPOSITS. 41 



Tlio liouldcr-clay locally pivsciits, as above slated, iudi- 

 calions of successive layers, and il occasionally contains 

 surfaces on which lie lar.ye boulders striated and ])olislied 

 on the u])i)er surface, in the manner of the ])avenu'nts of 

 l)oulders described by Miller, as occurring' in the Till of 

 Scotland. These ai)i)earances are, however, inre, and few 

 op])ortunities occur for obsei'xinu; them. 



A very general and imjxtrlant ai)])earancc is the polish- 

 ini;- and striation of the underlyini;- rocks usually to be 

 observed under the boulder-clay, and which is undoubtedly 

 of the same character witli that observed under Alpine 

 o'laciers. This continental striation or uroovinj;- is obvi- 

 ously the ettect of the action of ice, and its direction 

 marks the course in which the abrading a,t>ent travelled. 

 This direction has been ascei'taini'd l)y the Canadian and 

 United States surveys, and by local obsei'vers, over a 

 large part of America, ami it ])resents some broad features 

 well deserving attention. A valuable table of the direc- 

 tion of this striation is given in the "(ieology of Canada," 

 which I may take as a basis for my remarks, adding to it 

 a few local observations of my own.* The table end)races 

 one hundred and forty-five observations, extending along 

 the valleys of the St. Lawrence and the Ottawa and the 

 borders of the great lakes. In all of these the direction 

 is south, with an inclination to the west ami east, or to 

 state the case nu)re pi'ccisely, there are two sets of striae, 

 a south-west set and a south-east set. In the table 

 ei<ditv-four are westward of south and tifty-eight are 

 eastward of south, three being due south. It further 



* See also, iov the western distriots, Whittlesey's Memoir in the 

 Smithsonian C;ontril»utions, and Newherry's Report on Ohio ; Papers 

 by Dr. (!. M. Dawson on tiie Plains of N.W. Canada in Journal of 

 (ieol. Soy. of London and Trans. R.S. (.Canada. 



