Cb. XIV.] THE LAND HAS NOT SUBSIDED. 2G3 



ice scoops out all the contents of the valleys, and in 

 deepening them does not sort the materials like running 

 water or the action of the waves upon the sea coast. I 

 have in another place* shown that in Nova Scotia, in the 

 neighbourhood of rich auriferous quartz veins that have 

 been greatly denuded, grain gold is only sparingly dis- 

 seminated throughout the drifts of the valleys, whilst in 

 Australia every auriferous quartz vein has been the 

 source of an alluvial deposit of grain gold, produced by 

 the denudation and sorting action of running water. 

 "When the denuding agent was water the rocks were 

 worn away and the heavier gold left behind at the 

 bottom of the alluvial deposits ; but when the denuding 

 agent was glacier ice the stony masses and their metallic 

 contents were carried away, or mingled together in the 

 unassorted moraines. 



That the transportation of boulders in Nicaragua was 

 due to glaciers, and not to floating icebergs, may be 

 argued on zoological grounds. The transported boulders, 

 near Ocotal, are about three thousand feet above the sea, 

 those near Libertad about two thousand feet. The low 

 pass between the Atlantic and the Pacific oceans, through 

 the valley of the San Juan and the Lake of Nicaragua, 

 is less than two hundred feet above the sea,f and to 

 allow for the flotation of icebergs at the lower of the two 

 places named, a channel of more than eighteen hundred 

 feet in depth would have connected the two oceans. 

 This supposition is negatived by the fact that the mol- 



* " The Glacial Period in North America," by Thos. Belt. Pub- 

 lished in Trans. Nova Scotian Institute of Natural Science, 1866, 

 p. 93. 



t See ante, p. 35. 



