356 Analysis of Scientific Books and Memoirs. 



earliest ages of the world ; so that we need not shrink from attributing 

 to its agency effects far exceeding in magnitude those of which it ap- 

 pears capable at present. " One decided proof of the slowness of the 

 process of excavation, wherever it occurs, exists in the sinuosity of water- 

 channels, and in such a case, and such are met with even amongst the 

 largest river vallies, it is idle to talk of transient deluges or debacles as 

 the excavating agent.'' 



With regard to the periods at which the different continents may have 

 been heaved upwards, our author concludes, from the analogy of the 

 volcanic phenomena, that such elevations took place by successive shocks ; 

 the greater number being of minor violence, similar to the earthquakes 

 which occur at present ; but some of prodigious power, (paroxysmal ex- 

 pansions,) and analogous to the paroxysms of habitual volcanos. If it 

 is true, that outliers of the plastic clay and chalk have been recognized 

 on the highest summits of the Alps, it would appear that this colossal 

 chain, and perhaps with it the whole continent of Europe, owes its eleva- 

 tion from beneath the sea to some catastrophe of this nature, at what 

 we are accustomed to reckon a comparatively recent geological epoch. 

 The traces of diluvian action, the boulders of the Alps and Sweden, 

 and the alluvium of the north of Europe, may have been produced 

 by the retreat of the ocean from this elevated surface, and the 

 successive oscillatory movements to which it must have been subjected 

 before it regained its level. Other paroxysmal expansions may have oc- 

 curred in earlier ages of the globe's history, and in the old red sandstone 

 formation, it is observed, we may perhaps trace the result of such a ca- 

 tastrophe. The occurrence of repeated elevations on a large scale, is, in- 

 deed, attested by numerous geological facts. It is also probable, from 

 what we know of the power by which they are occasioned, that 

 they were far more frequent and violent in the early part of the history 

 of the earth than they can be at present ; for, unless we suppose the pro- 

 portion of caloric transmitted from the interior of the globe towards its 

 surface to have been always on the increase, (which is directly the re- 

 verse of the opinion professed by the author,) it is clear, that the con- 

 tinual and general increase of the repressive force, by the additions made 

 to the solid strata of the globe, in the products of volcanos, and incrust- 

 ing springs, and also to the body of water and atmospheric fluids which 

 press upon that surface, must have proportionately diminished the ratio 

 of subterranean expansion, from the commencement of the process up to the 

 present day. The author then adverts to the mineral nature of the ge- 

 neral subterranean bed of crystalline rock, (or lava.) This he concludes 

 to be probably granitic ; and supposes that some of the elevated portions 

 of it, may, by the effect of repeated intumescences, and reconsolidations, 

 under varying circumstances of temperature and pressure, by which the 

 component minerals would be more or less disintegrated, decomposed, 

 and their elements recombined in new proportions, and on separate 

 points, have been converted into syenite, greenstone, porphyry, compact 

 felspar, serpentine, diallage rock, &c. The analogy of ordinary volcanic 



