Geology and Mineralogy. 61 
It appears to me that the conditions which are said to have re- 
sulted in the production of the “stone rivers” of the Falklands 
here exist in equal if not greater force. There is the thick, spongy, 
vegetable mass covering the hillsides and acted on by varying con- 
ditions of extreme moisture and comparative dryness; there are 
the loose blocks of disintegrating syenite to be transported; and 
there are the mountain-torrents, lakes and sea-channels to remove 
the soil. Of actual motion of the soileap we have at least strong 
presumptive evidence; but nowhere in the valleys have I found 
anything resembling a “stone river. 
It might perhaps be thought that a slow and gradual depression 
of the land would account for some of the above phenomena ; 
I have seen no reliable sign whatever of subsidence, and have, on 
the contrary, the evidence of numerous raised beaches and the 
vaporation and eccentricity as co-factors in Glacial periods. 
—Rey. E. Hixx discusses this subject in a paper published in the 
Geological Magazine, viii, p. 481, November, 1881. e observes 
that the capacity of air for aqueous vapor increases with the 
precipitation must occur. For example, a cubic meter of air at 10° 
C. and 20° 
evaporation at the mean temperature ; and, moreover, - 
peratures vary about a mean, increased variation produces in- 
creased evaporation. A egree of eccentricity in the terres- 
ese considerations support Croll’s view of the relation 
between high eccentricity and glacial periods. ough this 
effect of evaporation is here clearly recognized for the first 
time, it is among the agencies whose combined influence was 
