ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixv 



conditions in certain minor areas, while they remain more constant 

 in others, will, doubtless also, eventually give great insight into the 

 distribution of land and water at equal geological epochs, and all the 

 intermingling of ordinary detritus, gravels, sands and mud will have 

 to be well studied for their extent, and modification both as regards 

 surfaces overspread and differences in the kind and direction of 

 supply. 



Waiting these more detailed investigations, and the modification 

 of views which may result from them. Sir Roderick Murchison has 

 taken marine life as his guide, and more particularly points to a vast 

 sheet of matter, including certain animal remains, as, to use the 

 happy term of Alexander von Humboldt, a geological horizon ; as- 

 suming that the animals, of which these are the remains, lived at the 

 same geological time, and therefore that the mineral masses in which 

 they have been entombed will bear classification in one group. We 

 have seen that in the case of the nummulitic rocks, he refers the de- 

 posits including these shells to the age of the lowest tertiary accumu- 

 lations, or the eocene rocks. 



Whatever views may be entertained of the existence of centres 

 whence species have to be distributed during the lapse of time, and 

 the consequent changes that all our classifications of the deposits 

 upon one portion of the earth, such as Europe, may eventually 

 have to undergo, as regards fine divisions made in accumulations 

 from the absence or presence of certain species or their representa- 

 tives of the same time, when other regions of equal area have been 

 carefully examined, the gathering up of evidence in favour of the 

 distribution of similar life in the seas of equal geological time, 

 as has now been done with respect to the nummulitic rocks of 

 Southern Europe by Sir Roderick Murchison, is very important. 

 Under our present amount of information respecting the wide area 

 noticed, extending even to India, it gives a leading object for a guide ; 

 and whether some of the myriads of nummulites found in these beds 

 first existed or not at the time of the chalk in particular districts, is 

 unimportant as regards the progress of the inquiry. If they be 

 shown in given areas to be limited to certain periods, the facts are at 

 least good as respects the reasoning for those areas. 



From the accidental circumstance of the tertiary rocks having been 

 made known to us by the labours of such men as Cuvier and Bron- 

 gniart, working around such a seat of science as Paris, a desire to 

 perpetuate very marked distinctions between the cretaceous and su- 

 pracretaceous accumulations has not unnaturally been experienced. 

 Those among us who are old enough, either to remember the actual 

 announcement of the labours of these distinguished men, or who en- 

 tered upon geological life sufficiently near that time to recollect the 

 feeling then existing among those who cultivated our science, will not 

 be surprised at the reluctance which has been so long experienced at 

 considering the accumulations of mud, sand, gravel, calcareous or 

 other matter of the one time as a mere sequence of those of the other, 

 and the breaks in this sequence in particular areas as no more than 

 other breaks in the general deposits of other geological times, even in 



VOL. V. — PART I. e 



