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THE FAllMEK^S MAGAZINE. 



new and horizontal layer of ice was formed, we should at least 

 be able to say with certainty that the time at which the wedge 

 was protruded was subsequent to the formation of the first 

 coating of ice, and previous to the second. This is the simple 

 reasoning applied to the age of mountains. For instance, in 

 the Pyrenees the chalk is seen disposed at a steep angle on 

 either side of these mountains, broken through like the up- 

 turned pieces of ice by a wedge of granite, while the tertiary 

 strata are nearly horizontally disposed upon and against the 

 nearly vertical chalk, showiug the latter, like the second layer 

 of ice, to have been more recently formed. Thus the age of 

 the Pyrenees must be between that of the upheaved chalk beds 

 and the more level tertiaries ; and by similar facts and induc- 

 tions other ranges may he proved, of various ages, from the 

 Cambrian and Silurian periods upwards. 



It 1)83 always seemed to me that the assumption of an in- 

 candescent liquid mass, produced by condensation of vaporoua 

 matter, is as purely gratuitous as the theory of the condensa- 

 tion of the nebul.ii themselves, which modern astronomical in- 

 struments have shown to consist of myriads of solid worlds 

 clustered in various forma, presenting by the collective trans- 

 mission of their rays the appearance of a luminous cloud ; and 

 that even if condensation had taken place, it did not follow as 

 a necessary sequence that the liquid substance produced should 

 be of a high temperature. In the most familiar illustration of 

 sudden condensation, that of the production of water by the 

 explosive combination of two gases— oxygen and hydrogen — I 

 am not aware that the water produced has a temperature equal 

 to the boiling point at the moment of production, or that its 

 temperature is raised considerably above that of the atmos- 

 phere; the heat in this case is evolved in the prod\iction, not 

 retained in the substance produced. The component gases 

 too may previously have been of low temperatures, while the 

 gradual refrigeration of the elements of our planet would pre- 

 sent the assumption that in the primary vaporous state there 

 must have been a still greater degree of heat than is now either 

 presumed possibly to exist, or than was present at the epoch 

 of the first reduction to liquidity ; or the sudden condensation 

 would indicate the application of a third power, such as the 

 flame or spark, to the two gases of water. On the other hand, 

 it might be arg'jed that water is only the oxide of hydrogen, 

 aud that as nearly all the great masses of mineral substances 

 of ordinary occurrence are oxides of elementary bases, there is 

 in them all an evidence of a former gaseous condition. The 



equatorial region, as from general liquidity of its substance ; 

 and if, even by some perversity. Nature had developed it after 

 a spindle-shaped fashion, the constant action of the atmosphere, 

 of rivers, aud of currents, during the lapse of vast ages, would 

 ultimately have reduced it, by wearing down the land of the 

 poles, and depositing the materials in the deeper waters of the 

 median area, to that spheroid of rest which it now presents. 



[Lion. 4.— Obliile sf lioroidal form of our globe ] 



Bpheroidal form of the globe would arise equally from the na- 

 tural action of the water on its surface in trending towards the 



[Lion. 5.— Comparative thickness of the crust of the earth, 

 the geological conditions of which are known. Height of 

 atmosphere.] 



Without pursuing this subject any farther, we may see how 

 purely speculative is this portion of geology ; and how easy it 

 is, when we quit the examination of recent and present actions 

 and their application to the past condition of our world, to get 

 into a sea of doubts and difRculties, and to end in bewilder- 

 ment and dismay. How different is the case when we regard 

 any of these phenomena of which we have the key in those 

 which are taking place around us ! Let us take, for instance, 

 the case of chalk, or any other ordinary limestone, with its 

 associated beds of clay and sand. We find these representing 

 in their mineral conditions the dried mud and silt and sands 

 of our shores ; we find, further, both sets contain the shells of 

 the molluscs which have burrowed into and lived in them ; aud 

 that both are stratified, that is, that they consist of layers of 



[LiGN. 0.— Illustration of stratified rocks. Cretaceous strata 

 at Folkestone, Kent, dipping 7* E.X.E.] 



matter deposited one over the other, as we see film after film 

 of mud, or sand, daily and successively deposited by the ocean 

 on our coastf. We find that the shells, imbedded in the 

 ancient rocks, are comparable to recent fresh-water or marine 

 forms, and that they are associated with fish, plants, algne, or 

 other organisms, which add to the evidence whether the 

 rocks under examination were the produce of the sea or lake. 

 We find, moreover, that these beds of limestone, clays, and 

 sandstone, as they are presented to us at the surface of our 

 earth, are not always horizontal nor parallel ; that more 

 commonly each dips in some particular direction, and that 

 their inclination is ofcen at a much more considerable angle 



