Tin; P08T-PLIO i.m . 27 



by the tidal currents sweeping up the coast, or by the Arctic current 

 from the north, and deposited on the surface of Prince Edward [eland, 

 then a shallow sand-bank. The sands with sea-shells probably be- 

 longed to this period, or perhaps to the later part of it, when the 

 land was gradually rising. Prince Edward Island thus appears to 

 have received boulders from both Bides of the Gulf of S1 Lawrence 

 during the later Post-pliocene period ; but the greater number from 

 the south side, perhaps because nearer to it. It thus furnish* - 

 remarkable illustration of the transport of travelled Btones at this period 

 in different directions; and in the comparative absence of travelled 

 stones in the lower boulder clay ; it furnishes a Bimilar illustration of 

 the homogeneous and untravelled character of that deposit, in circum- 

 stances where the theory of floating ice serves to account for it at 

 least as well as that of land ice, and, in my judgment, greatly better. 



Subdivisions of the Pleistocene Deposits. — In Chapter V., and in my 

 Memoirs on the Pleistocene of the St Lawrence Valley, I have proposed 

 a threefold division of these beds into Boulder "clay, Leda clay, and 

 Saxicava sand and gravel, to which may be added the old p< 

 deposit observed under the boulder clay in Cape Breton. Mr 

 Matthew has since recognised in New Brunswick certain beds only 

 locally developed in the St Lawrence Valley, and which I have been 

 hitherto disposed to regard as depending on the action of streams 

 from the land or littoral agencies, but which he regards as marine 

 deposits. They are gravels and sands underlying the boulder clay, 

 and as yet destitute of fossils. lie suggests for these the name 

 " Syrtensian " beds, proposed by Packard for the fauna of the Great 

 Bank deposits of the Newfoundland and New England coasts, bul the 

 application of which to the beds in question depends on a tin 

 of their origin not yet certainly established. He also recognises, as I 

 have done in the St Lawrence Valley, a lower and upper member of the 

 Leda clay — the latter being equivalent in its fossils to the Uddevalla 

 beds of Sweden. The complete series of Pleistocene beds in Acadia 

 and Canada would thus stand as follows, in ascending order, though 

 it is to be observed that the whole series is not to be found 

 developed at any one place : — 



(a.) Peaty terrestrial surface anterior to boulder (day. 



(b.) Lower stratified gravels — (Syrtensian deposits of Matthew). 



(c.) Boulder clay and unstratified sands with boulders. Fauna, 



when present, extremely Arctic. 

 (d.) Lower Leda clay, with a limited number of highly Arctic shells, 



such as are now found only in permanently ice-laden Si 

 (e.) Upper Leda clay and sand, or Uddevalla beds, holding many 



