GLEN ROY, IN SCOTLAND. 
39 
consideration, indicates only a comparatively 
slight change of relative level between sea and 
land within a narrow belt along the shores; 
and even this is shown to be posterior, not 
anterior, to the glacial phenomena. As to 
the supposition that the motion proceeded from 
the sea towards the land, all the facts are 
against it, since the whole trend of these phe¬ 
nomena is from inland centres toward the 
shore, instead of being from the coast up¬ 
ward. 
Certainly, no one familiar with the facts 
could suppose that floating ice or icebergs had 
abraded, polished, and furrowed the bottom of 
narrow valleys as we find them worn, polished, 
and grooved by glaciers. And it must be 
remembered that this is a theory founded not 
upon hypothesis, but upon the closest compar¬ 
ison. I have not become acquainted with these 
marks in regions where glaciers no longer ex¬ 
ist, and made a theory to explain their pres¬ 
ence. I have, on the contrary, studied them 
where they are in process of formation. I 
have seen the glacier engrave its lines, plough 
its grooves and furrows in the solid rock, and 
polish the surfaces over which it moved, and 
