358 Analysis of Scientific Books and Memoirs. 



tcr raised, and the amount of its elevation. The coarser fragments trans- 

 ported by such moving waters, will have been deposited in the longitudi- 

 nal vallies of mountain ranges, and wherever' the currents were first con- 

 siderably checked. The finer detritus will have afterwards subsided, 

 when the ocean had regained its equilibrium, and mixed with the precipi- 

 tations which were taking place contemporaneously from its waters, and 

 with the bituminous and calcareous matter, proceeding from the decomposi- 

 tion of vegetable and animal substances, the shells of molluscse, co- 

 ralline bodies, &c. produced the sedimentary formations. As the depth of 

 these beds of pulpy matter increased, the consequent pressure upon the 

 lowest of them, by bringing the similar particles slowly and gradually 

 within the sphere of action of their mutual attractive forces, occasioned 

 the successive formation of separate horizontal concretions, or strata, more 

 or less fully consolidated, which some subsequent expansion elevated 

 above the sea-level, where they lost by drainage all the water they contain- 

 ed, and were by desiccation still farther indurated- 



The author opposes the Huttonian theory, that these strata were har- 

 dened by heat from the interior of the globe, which he thinks wholly 

 disproved by the occurrence of clays and shales beneath indurated strata. 

 The consolidation of limestones, sandstones, &c- he attributes solely to 

 a concretionary action, accompanied by a more or less imperfect crystalli- 

 zation of the very finest particles which act as a cement to the coarser. 

 The more complete the process of crystallization, the more solid and 

 compact the rock ; and therefore the large- the proportion of precipitat- 

 ed matter, (which, as being much finer than any sediment, is more fa- 

 vourable to crystallization) the more crystalline and the harder will be 

 the strata. It is well known that, amongst the stratified rocks, the older 

 are generally the most crystalline, and hence we should expect the 

 quantity of matter precipitated by the waters of the ocean to have been 

 greater in former times than now. The author attributes this to the high- 

 er temperature of the ocean in those ages, and the greater quantity of mi- 

 neral matter carried into it in a state of solution by the vapours evolved 

 from the interior of the globe. Even the more completely crystalline 

 rocks, such as statuary limestone, quartz rock, and rock salt, appear to 

 the author in the light of precipitations from the primitive ocean, where, 

 at this time, the sedimentary matter predominated, mica, talc, and chlo- 

 rite slates were deposited. With regard to gneiss, the lowest of the strati- 

 fied rocks, the author considers it to share in a very slight degree in 

 the character of a sedimental rock, to have been in short a granite 

 which, after a great degree of intumescence, was reconsolidated by the 

 pressure it sustained between the expansive force of the granite beneath, 

 and the weight of the solid strata which had settled above it, as well as of 

 the ocean and atmosphere. 



The author then generalizes these views as to the origin of the different 

 rock formations, in a " Sketch of a Theory of the Globe," of which the 

 following is a brief abstract. 



The mass of the globe, or at least its external zone to a great depth, is 



