STRATIFIED SAND AND GRAVKL. 



81 



for my belief stated in previous papers on this subject, that the 

 difference of climate between Post-pliocene and Modern America, and 

 the less amount of that difference relatively to that whicli has occurred 

 in western Europe, may be explained by a consideration of the changes 

 of level which the structure and distribution of the boulder clay and 

 the overlying fossiliferous beds prove to have occurred. 



The stratified sand and gravel of Nova Scotia rests upon and is 

 newer than the unstratifled drift, and is probably also newer than the 

 stratified marine clays above referred to. Its age is probably that of 

 the Saxicava sand. The former relation may often be seen in 

 coast sections or river banks, and occasionally in road-cuttings. I 

 observed some years ago an instructive illustration of this fact, in 

 a bank on the shore a little to the eastward of Mcrigomish harbour 

 (Fig. 22). At this place the lower part of the bank consists of 

 clay and sand with angular stones, principally sandstones. Upon 



Fig. 22. — Stratified Gravel resting on Drift, — Merigomish. 



this rests a bed of fine sand and small rounded gravel with layers of 

 coarser pebbles. The gravel is separated from the drift below by a 

 layer of the same sort of angular stones that appear in the drift, 

 showing that the currents which deposited the upper bed have washed 

 away some of the finer portions of the drift before the sand and gravel 

 were thrown down. In this section, as well as in most others that I 

 have examined, the lower part of the stratified gravel is finer than 

 the upper part, and contains more sand. 



In some cases we can trace the pebbles of the gravels to ancient 

 conglomerate rocks which have furnished them by their decay ; but 

 in other instances the pebbles may have been rounded by the waters 

 that deposited them in their present place. In places, however, where 

 old pebble rocks do not occur, we sometimes find, instead of gravel, 

 beds of fine laminated sand. A very remarkable instance of the con- 

 nexion of superficial gravels with ancient pebble rocks cocurs in the 

 county of Pictou. In the coal formation of this county there occurs 

 a very thick bed of conglomerate, the outcrop of which, owing to its 



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