140 u4n Inquiry into the Terrestrial Phcrnomena 



in thdr native beds, has been formed from the consolidation 

 of strata previously derived from aqueous deposition. Tlie 

 Vulcanists triunfiphantly assign the consolidation, and in 

 many cases maintain the actual fusion of the strata, to in- 

 ternal fires, alleging that a mere hardening by evaporation 

 of the moisture, m the stony matter, would neccssarilyleave 

 the rock in a state of porosity, which observation every- 

 where contradicts. The truth however is, that the assump- 

 tion of internal fires is as superfluous as it is visionary, and 

 the desiccation of solidifiable strata, under an incalculable 

 pressure of the superincumbent strata, aided by the agglu- 

 tination of stony matter in solution, during a period of in- 

 definite extent, is amply sufficient to account for the highly 

 indurated and dense state in which we now find all strati- 

 fied rock. 



The absolute completion of the solidifying process seems 

 however to require an emersion above the level of the ocean ; 

 for it i-; difficult to imagine how many of the species of rock 

 with which wc are acquainted, could have been both preci- 

 pitated and consolidated under one and the same immersion, 

 if there^is any truth in this observation, it would decide the 

 question of more than one submersion ; for there are nume- 

 rous instances of rock which bear conclusive evidence of the 

 attrition of marine action after their induration. The rock 

 of'Table Mountain at the Cape of Good Hope may he given 

 as one of these instances. It is repugnant to all rational be- 

 lief, to admit that the materials ot that vast rock experienced 

 an aqueous deposition, a subsequent consolidation, and a 

 final destructive denudation to its present state, all under 

 one and the same immersion. 



The numerous breaks and separations which traverse the 

 strata, designated faults, throws, heaves, troubles, and 

 other nan)es expressive of their effects in njining, are also, I 

 think, evidence of distinct immersions. Their frequent 

 rectilinear direction, and their worn and abraded angular as- 

 perities, fully prove that they were formed after the consoli- 

 dation of the strata in which they occur, and also, I conceive, 

 establish them to have been originally chasms, gullies, ra- 

 vm^s, valleys, channels, and other land excavations, clefts 

 and fissures, and to have been filled up in a subsecjuent im- 

 mersion. 



Mineral veins in extensive fissures which traverse stratified 

 rock, can, I imagine, only be referred to the same origin, 

 and therefore testify the same result. The minerals have 

 assuredly obtained their present situation in an immersion 

 entirely distinct from that in which the strata were formed. 



The 



