•286 
GLACIAL THEORIES. 
There are geologists who would gladly expunge the word " diluvial 
from our nomenclature, and instead of appealing to one or several 
general convulsions for the explanation of some striking fact, are 
willing to believe that small and local forces, operating through long 
time, are sufficient for the purpose of geological speculation." Mr. 
Greenough, who has been quoted in confirmation of the views held 
by Dr. Buckland, declares himself " incapable of distingnishing 
between the effects of such a deluge or deluges and subsequent 
phenomena produced by the ordinary agency of running water." The 
opinion now held with respect to the dispersion of rocks from their 
original sites to distant situations was that they had been removed, 
during the submergence of the whole country beneath the sea, by 
icebergs, and it was considered that the clays of Holderness, contain- 
ing enclosed masses of granite and syenite brought from Cumberland 
and Westmoreland ; of porphyritic granite of Shap Fell ; of lime- 
stone from the mountain districts of Yorkshire, and many others, 
were accumulated by this means, and that they passed over the 
Penine Escarpment at Stainmoor and proceeded down the valleys to 
their present position. The fact that there are no fragments of these 
rocks east of the Penine Chain, south of Boulswortli, was accounted 
for by the range of hills running north and south, and east and west, 
being so high as to have prevented the glacier passing over. 
It was reserved for a Swiss naturalist, M. Louis Agassiz, to 
dispel the generally accepted but erroneous ideas respecting these 
accumulations of detritus. Following in the track first indicated by 
Charpentier, Agassiz in 1836, spent his summer vacation in the 
valley of the Rhone, and there learnt how the ice of the glaciers 
carried the masses of rock from the mountains and scattered them 
over the valley, how the sides of the valley down which the glacier 
flowed was scoured and grooved by its action, and morainic matter 
piled high along its slopes, whilst the masses of stone torn by its 
action from their parent beds were rounded, smoothened, pohshed and 
scratched in their transit. From the consideration of the glacial 
phenomena existing in the Swiss mountains, Agassiz deduced the 
ancient extension of the glaciers over a much larger area of that 
country, and his knowledge of the features existing over Europe led 
