202 The Naturalist in Nicaragua 
are on natural exposures in some districts that have certainly 
been glaciated, and will not be surprised that in a hurried 
visit of only a few hours I should not have discovered any. 
Glacial scratches are seldom preserved on rock surfaces 
exposed to the action of the elements. Even in Nova Scotia, 
where scratches and grooves are met with wherever the rock 
surface has been recently laid bare, I do not remember 
having ever seen any on natural exposures. It is only 
where protected by a covering of clay or gravel from the 
action of the elements, that they have been preserved 
through the ages that have passed since the glacial epoch, 
and as I did not see any rock surfaces near Depilto that had 
been recently bared, it is not surprising that,.notwithstand- 
ing the other proofs of glacial action, I should not have seen 
any ice scratches or grooves. 
I could no longer withstand the evidence that had been 
gradually accumulating of the presence of large glaciers in 
Central America during the glacial period, and these, once 
admitted, afforded me a solution of many phenomena that 
had before been inexplicable. The immense ridges of 
boulder clay between San Rafael and Yales, the long hog- 
backed hills near Tablason, the great transported boulders 
two leagues beyond Libertad on the Juigalpa road, and the 
scarcity of alluvial gold in the valleys of Santo Domingo, 
could all be easily explained on the supposition that the ice 
of the glacial period was not confined to extra-tropical lands, 
but in Central America covered all the higher ranges, and 
descended in great glaciers to at least as low as the line of 
country now standing at two thousand feet above the sea. 
In my description of the mines of Santo Domingo I have 
only briefly alluded to the scarcity of alluvial gold in the 
valleys. It may be correlated with a similar scarcity in the 
glaciated valleys of Nova Scotia and North Wales, in the 
neighbourhood of auriferous quartz veins, and is probably 
due to the same cause. Glacier ice scoops out all the con- 
tents 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 
1 The Glacial Period in North America, by Thos. Belt. Published in 
Trans. Nova Scotian Institute of Natural Science, 1866, p. 91. 
