34 BULLETIN OF THE 



schist from all the ranges have indeed been transported southeasterly 

 into the adjoining valleys, but such fragments are entirely devoid of 

 linear arrangement. 



CONCLUSIONS. 



As boulders do not usually occur in trains, it is natural to inquire to 

 what circumstances the Richmond boulder trains owe their formation. 



The supposition of Sir Charles Lyell, that the boulders were trans- 

 ported to their present position by floating ice, has already been alluded 

 to (page 18). It of course implies that the level of the ocean must have 

 stood somewhat above the crest of the Canaan and Lebanon Range dur- 

 ing the formation of the trains, or, relatively to the land, 1,650 feet 

 above its present level. Other writers have shown that the same line 

 of argument which leads to this conclusion would necessitate a depres- 

 sion of parts of the glaciated region to 5,000 feet below their present 

 level, and they have also shown, from the absence of all marks of an 

 oceanic shore line at that height, and from other considerations, that 

 such a depression did not exist. 



Boulders of chloritic sandstone and of buff limestone have been alluded 

 to as occurring in the region under consideration upon the liichmond 

 Range, those of the former rock being at a height of 400 feet, and those 

 of the latter GOO and 800 feet above their source. Upon the iceberg 

 hypothesis, the position of these boulders cannot be accounted for, except 

 on the condition that the supposed ocean level rose several hundred feet 

 in the interval of transportation ; and it seems quite improbable that so 

 great a change of level could take place in the short time necessary for 

 the transporting icebergs to float the boulders two miles, the distance of 

 their farthest source. 



Supposing, with most geologists of the present day, that this region, 

 in common with a large part of the northern hemisphere, was, in the 

 Post-Pliocene age, covered with an ice-sheet, which had in certain dis- 

 tricts a thickness of several thousand feet, and had a slow movement, — 

 in this vicinity from the northwest towards the southeast, — why, as a 

 result of the rending action of the ice exerted upon the crest of the 

 Cana;m and Lebanon Range, are there not boulders of chloritic schist 

 scattered nearly uniformly over all the region to the southeast of that 

 range 1 Such an arrangement might have resulted, had there been, at 

 the time the material in question was being removed, a continnous out- 

 crop of chloritic schist along the whole crest of the Canaan and Lebanon 

 Range. 



