But my belief is founded on a reason which I hold to be so secure that, until some facts can be brought forward which demonstrate directly that these primeval mountains were not more lofty than those which we now have, I shall continue to think that our present mountains are but degenerate types of the mountains of antiquity.
The reason is a very simple one. The altitude of mountains depends primarily on the resultant of antagonistic agencies. There are the disturbances from below which push the mountains up, for were our earth solid and cold throughout its interior no fresh upheavals could arise. On the other hand, the disintegrating tendencies of air and water tend to reduce the elevations of the mountain summits. In the early days to which we refer the subterranean agents by which upheavals were produced were far more vehement than they are at present. I do not see any reason to think that there has been any corresponding large difference between the efficiency of the disintegrating energies then and their efficiency now. I therefore see no reason to doubt that in days so remote as those of which we are speaking the mountains may under certain circumstances have had greater elevations than any mountains of which we know. A volcano which has its vent in the summit of one of these exceptionally lofty mountains would discharge its missiles vertically, under conditions where the resistance of the atmosphere would be reduced to a mere fraction of that resistance which the artillerist so greatly abhors.
There are also other considerations which may be brought forward in relation to the question of atmospheric resistance. In a vast volcanic outbreak a prodigious volume of gases accompanies the more solid materials
