J. \V. SPENCEB — ANCIENT SHORE PHENOMENA. 



"Artemisia gravel" is a Dame applied by the Canadian Geological Survey 

 to the gravels covering an area of 2,000 square miles of the highest land in 

 Ontario, between the three hikes. Buron, Erie, and Ontario, rising in places 

 to 1,700 feel above the sen. But the Canadian Survey did not recognize 

 the different kinds of gravel accumulations. Indeed, its whole work upon the 

 drift of Ontario was only pioneering, and now being somewhat antiquated 

 and generalized, it is but a poor guide along a pathway enlightened by 

 modern investigations. Thus the term Artemisia includes sand, gravel, and 

 even upper till deposits (the last, although occupying thousands of miles 

 of the Burfaceofthe Province, was not identified by the Survey) of all kinds 

 and ages mentioned in this chapter and in that on beaches. However, it 

 was the accumulation of the gravels described in this group II b, in the 

 township of Artemisia, that gave the name which was extended over such a 

 wide range of materials and geological time as if all were one formation. 

 At most, the term should be restricted to the ridges occupying the position 

 of very high-level beaches, just described. 



II e. — Gravel plains are common in front of such highdevel ridges as 

 have been last described, representing the subaqueous floors when the waves 

 beat upon the old shores. Some of them, however, may be the floors of 

 terrace- cut into the older gravel deposits. The plains are often very deeply 

 eroded, owing to the high elevation of the country and the long action of 

 meteoric agencies upon the incoherent materials. Thus, there sometimes 

 remain of these plain- only a succession of ridges, between ravines deeply 

 excavated by the numerous streams and floods. Such plains occur in the 

 typical region of the Artemisia gravel in Ontario, in .Michigan, and in 

 other States. 



University of <i'><>r(/ia, August, 1889. 



