564 



Dr. W. B. Carpenter on the 



[June 13 ; 



used in my First Report (1868, p. 193), that u we may be said to be still 

 living in the Cretaceous epoch." We then anticipated — what our own sub- 

 sequent inquiries and those of our friends of the United States Coast Survey 

 have abundantly confirmed — that with the persiscence of the Globigerine 

 life which forms the Cretaceous deposit, there would prove to be a like 

 persistence of numerous types characteristic of the old Cretaceous Fauna ; 

 so that the Globige?'ina-mvi& now in process of increase on the sea-bed of 

 the Atlantic may be regarded " not merely as a Chalk-formation, but as a 

 continuation of the Chalk-formation." Now we have been told on high 

 authority that Geological epochs are essentially marked out by great changes 

 in the Fauna, — whole series of Animal forms disappearing, and their places 

 being taken by others which then first make their appearance ; and further, 

 that the termination of the Cretaceous Epoch must be considered, in this 

 sense, as coinciding with the disappearance of those numerous types of 

 chambered Cephalopods which were so eminently characteristic of the 

 Old Chalk, and of which very few appear to have survived the changes that 

 inaugurated the Tertiary epoch*. 



44. There is nothing really inconsistent, however, between Sir Charles 

 Lyell's view of the case and our own. If his definition of a Geological 

 Epoch be accepted, then our doctrine that " we may be said to be still living 

 in the Cretaceous epoch " requires to be expressed in somewhat different 

 language. But if that which we meant to be understood by it, and which 

 has been admitted as probable by so eminent an authority in Geology as 

 Mr. Prestwich, should be really the case, then, I submit, some new term 

 must be invented to designate that state of things which will present itself 

 to the " Geologist of the future," whenever the present bed of the Atlantic 

 shall be raised into dry land. For there will then be found superimposed 

 upon the newest beds of what is now known as the " Cretaceous Formation," 

 not a series of deposits resembling the Tertiaries of Europe and America, 

 but an unbroken succession of layers of a substance resembling the Old 

 Chalk in all essential particularst, and containing numerous Animal types 

 which do not differ more from those of its uppermost beds than these do 

 from the types found in the earlier members of the Formation. Doubtless 

 there will be a great and perhaps a sudden change in certain portions of 

 the Fauna ; but whilst the material of the deposit continues unchanged, 

 whilst its Stratification remains conformable, and a large number of Generic 

 types can be traced continuously throughout, I venture to think that the 



* Sir Charles Lyell's ' Student's Elements of Geology,' p. 263. 



f Much stress has been laid on the fact that the specimens of the Atlantic mud brought 

 up by our dredge proved on analysis to contain a considerable admixture of Sand, and 

 could not be said to be true Chalk. But this admixture may very probably have been 

 purely local, resulting from the drift of the Northern detritus along a line of specially 

 rapid underflow. According to Dr. Bailey and Prof. Huxley, the Atlantic mud brought 

 up by the Sounding-apparatus from the Mid-ocean scarcely contained a trace of sand ; 

 and the non-communication of the Cretaceous Sea with the Polar area may not im- 

 probably be the explanation of the purity of the Old Chalk. 



