President of the Geological Society for 1850. 15 



First, that our present inability to decipher some of the 

 monuments of past ages by a key derived from the effects of 

 causes now acting, ought never to be adduced as an argu- 

 ment of much weight in favour of the paroxysmal theory ; 

 for it might with equal or greater propriety be urged as a 

 reason for believing in the adequacy of existing causes, or 

 their identity with those of former times, since no one doubts 

 that we are ignorant of the nature of many subterranean and 

 suboceanic changes now in progress. If tlierefore there was 

 nothing obscure or mysterious in geological phenomena, if 

 they simply presented to us a picture of objects as familiar 

 as the lavas of Vesuvius or the calcareous tufas of mineral 

 springs, or the newly-formed deposits of a delta seen at low 

 water, we should be entitled to suspect a great want of ana- 

 logy between the ancient and modern processes at work above 

 and below the earth's surface. We should then be entitled 

 to ask, where are the nether-formed and deep-sea formations 

 of the olden time \ Where are the signs of those changes 

 brought about in the bowels of the earth corresponding to such 

 as are nowin progress in regions inaccessible to human observa- 

 tion \ Why have not the causes which have upheaved moun- 

 tains and deeply fissured the rocks, or which have denuded 

 large areas, revealed to us ancient stratified and unstratified 

 rocks, wholly distinct from any which we now see generated by 

 ordinary volcanic action or formed in lakes and shallow seas \ 

 Secondly, it should be thoroughly understood that the decision 

 of the question at issue can in nowise be determined by simply 

 comparing the magnitude of the changes brought about in 

 historical times with those of antecedent periods. It may be 

 safely afiirmed, that the quantity of igneous and aqueous 

 action, — of volcanic eruption and denudation, — of subterra- 

 nean movement and sedimentary deposition, — not only of 

 past ages, but of one geological epoch, or even the fraction 

 of an epoch, has exceeded immeasurably all the fluctuations 

 of the inorganic world which have been witnessed by man. 

 But we have still to inquire whether the time to which each 

 chapter or page or paragraph of the earth's autobiography 

 refers, was not equally immense when contrasted with a 

 brief era of 3000 or 5000 years. The real point on which 



