064 Reports and Proceedings—Duke of Argyll’s Address. 
it could have placed boulders as we find them placed. This, however, 
is understating the objections to the ice-cap theory, because these 
objections are not merely negative. Other objections are positive in 
their testimony. The glaciation of the rocks upon our mountains 
seems to me to prove conclusively that it was not done by one continu- 
ous sheet pressing itself with enormous weight into all the sinuosities 
or inequalities of the surface, but was done by the impingement of 
floating sheets and masses upon particular portions only of the surface 
—those portions almost always explaining most clearly the agency 
which abraded them by their relation to currents such as existing con- 
tours would modify and direct. 
I object, also, on physical grounds, as well as on the ground of re- 
butting evidence, to the theory of an ice-cap, or of ice masses under 
whatever name, which at all approach in magnitude those which are 
continually invoked by the extreme glacialists. There is no proof that 
such masses ever existed any more than they exist now. But if they 
ever did exist, I see no possibility of their ever having had the move- 
meuts which are habitually ascribed to them. There may be some 
points not yet perfectly understood in the motion of true glaciers. 
But I am satisfied with the explanation of Principal Forbes and others. 
In gravitation we have a true cause—a vera causa—of motion in ice- 
masses resting on the slopes of amountain. But there is no proof that 
gravitation would produce a forward movement upon ice-masses which 
do not rest upon the slopes of a mountain, but upon level surfaces. 
Still less is there any adequate cause assigned for such motion when it 
is actually opposed to gravitation, and is assumed to have carried 
mountains of ice up the slopes and over the tops of mountains of 
rock. Such suppositions have always appeared to me to be catastro- 
phism in its most extravagant form. It is one thing to explain effects 
by invoking greater energy of action for causes which are at least 
known to exist and to be certainly capable of producing them—it is 
another and a very different thing to invoke agencies which are not 
known to exist at all, and which if they did exist are not known to be 
capable of producing the effects ascribed to them. Greenland is some- 
times quoted asa case of an ice-cap. But Greenland isin reality nothing 
but a case of one enormous ‘‘nevé’’ and a series of gigantic glaciers. 
It is a high mountain country, buried under an excessive snowfall, — 
with that snow consolidating into a series of glaciers in all the valley 
beds. The cause of motion in the ice-masses which debouche into the 
sea round the coast of Greenland is precisely the same cause of motion 
which brings an ice cliff into the Valley of Chamounix. Then as to 
the ice-masses which occupy the highest latitudes of the Antarctic 
Circle, it will be time enough to reason upon its phenomena when we 
really know them. As matters now stand, we have no proof whatever 
that the ice of the Great Southern Barrier moves steadily over a high 
mountain surface under any unknown impelling force. I have dwelt 
longer upon this question of the ice-cap or ice-sheet, because it is not 
in the geology of our own island only that it is invoked to get rid of the 
conception of a great submergence, and of a great re-elevation of the land 
—both of them effected in the most recent times. On the continent of 
Europe, too, we know that a large part of its central area is occupied by a 
