[45] Tonson’s Ed. of 1758. Bacon may have had this passage in mind when he wrote, “It must not be thought that heat generates motion, or motion heat (though in some respects this be true), but that the very essence of heat, or the substantial self of heat, is motion and nothing else.”—Novum Organum, book ii. Devey’s Translation.
If the Alps were granted a perfectly invariable temperature, if they were no longer subjected alternately to freezing blasts and to scorching heat, they might more correctly be termed “eternal.” They might continue to decay, but their abasement would be much less rapid.
When rocks are covered by a sheet of glacier they do enjoy an almost invariable temperature. The extremes of summer and winter are unknown to rocks which are so covered up: a range of a very few degrees is the most that is possible underneath the ice.[[46]] There is then little or no disintegration from unequal expansion and contraction. Frost then does not penetrate into the heart of the rock and cleave off vast masses. The rocks then sustain grinding instead of cleaving. Atoms then come away instead of masses. Fissures and overhanging surfaces are bridged, for the ice cannot get at them; and after many centuries of grinding have been sustained, we still find numberless angular surfaces (in the lee-sides) which were fashioned before the ice began to work.
The points of difference which are so evident between the operations of heat, cold and water, and the action of glaciers upon rocks, are as follow. The former take advantage of cracks, fissures, joints and soft places—the latter does not. The former can work underneath overhanging masses—the latter cannot. The effects produced by the former continually increase, because they continually expose fresh surfaces by forming new cracks, fissures and holes. The effects which the latter produces constantly diminish, because the area of the surfaces operated upon becomes less and less as they become smoother and flatter.
[46] Doubtless, at the sides of glacier-beds, the range of temperature is greater. But there is evidence that the winter cold does not penetrate to the innermost recesses of glacier-beds in the fact that streams continue to flow underneath the ice all the year round, winter as well as summer, in the Alps and (I was informed in Greenland) in Greenland. Experimental proof can be readily obtained that even in midsummer the bottom temperature is close to 32° Faht.
What can one conclude, then, but that sun, frost and water have had infinitely more to do than glaciers with the fashioning of mountain-forms and valley-slopes? Who can refuse to believe that powers which are at work everywhere, which have been at work always, which are so incomparably active, capable and enduring, must have produced greater effects than a solitary power which is always local in its influence, which has worked comparatively but for a short time, which is always slow and feeble in its operations, and which constantly diminishes in intensity?
Yet there are some who refuse to believe that sun, frost and water have played an important part in modeling the Alps, and hold it as an article of their faith that the Alpine region “owes its present conformation mainly to the action of its ancient glaciers”![[47]]
[47] Professor Tyndall “On the conformation of the Alps,” Phil. Mag., Sept. 1862.
My reverie was interrupted by Croz observing that it was time to be off. Less than two hours sufficed to take us to the glacier plateau below (where we had left our baggage): three-quarters of an hour more placed us upon the depression between the Grand Cornier and the Dent Blanche (Col du Grand Cornier), and at 6 P.M. we arrived at Albricolla. Croz and Biener hankered after milk, and descended to a village lower down the valley, but Almer and I stayed where we were, and passed a chilly night on some planks in a halt-burnt châlet.