A lecture on the progress of physical science since the opening of the London Institution / by W.R. Grove.

  • Grove, W. R. (William Robert), 1811-1896.
Date:
1842
Catalogue details

Licence: Public Domain Mark

Credit: A lecture on the progress of physical science since the opening of the London Institution / by W.R. Grove. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    In assenting generally to the tlieory of Lyell, I would be considered as doing so with some reservation. I am far from thinking that the changes of Nature have always occurred with precise regularity; on the contrary, I am inclined to think that there have been periods at which Nature has un- dergone changes far beyond her normal ones; while there have been others at which she has been more than usually stationary. Etna bursts not forth every day, nor are her eruptions of equal grandeur; and if in our own time Nature acts not with perfect uniformity, we have no right to assume that she has done so in times past: still in the long lapse of ages these variations are scarce notable; like the waves on the sea-surface, they are altogether lost in perspective. A new agent has been recently discussed as having con- curred and as now concurring to produce various geological changes : namely the action of Glaciers. From an examina- tion of Alpine tracts, where, from an increase of temperature, the glaciers have receded, it has been found that peculiar marks called Glacial-scratches, remain; marks which are made by the shifting of vast masses of ice, and which no other known natural force can effect. In other places are found blocks of stone and gravel in connexion with polished and striated rocks, which have resulted from similar glacial action; in others moraines, or terraces on the flanks of valleys formed of detritus of blocks and pebbles, which by their polish and position afford strong evidence of having been there de- posited by the melting of the ice. These formations differ from stratified-gravel produced by ordinary aqueous deposi- tion ; as here the ingredients are smaller, and the finest portions are at the top, while in glacier-detritus large and small blocks are intermixed, and the superposition depends more upon the shape than upon the size of the masses. Similar appearances to these have been observed at far distances from the Alps, in various parts of the northern and temperate regions of the earth; and the conclusion is imme- diate, that they must have been produced by similar causes. The observation of these remarkable facts, most of which are due to Professor Agassiz, have opened a new field of c