ANNIVEESART ADDRESS OF THE PRESIDENT, Ixix 



It is more difficult to understand the absence of later Quaternary 

 shells, such as those of the Clyde beds, only three of which have 

 been recognized among the late dredgings. Does it arise from the 

 more littoral and shallow forms of that class being stayed by cli- 

 matal conditions near our shores, while the deeper-sea forms passed 

 on southward free from the influences which aifected the others? 

 That a great proportion of the deep-sea forms had migrated during 

 and since that period is probable from their wide diffusion and large 

 numbers. Mr. Jeffreys has enumerated fifty of these more recent 

 northern Mollusca which are not known in a fossil state ; and of 

 the Echinoderms and Crustacea mentioned by Dr. Carpenter and 

 Prof. "Wyville Thomson a large proportion are Norwegian, Spitz- 

 bergen, and other high-northern forms. 



From what I have previously said, you will have understood that, 

 lithologically, there is but little resemblance between the Atlantic 

 mud and our typical white chalk, none that could have ever led a 

 geologist into any error of determination. In fact, in no part of the 

 area yet explored is there any thing at all to be identified lithologi- 

 cally with the true white chalk. Even if it were found that the 

 superposition were conformable, the difference of mineral character 

 is too marked. At the same time it is to be observed that the area 

 of the Atlantic is so vast that, variable as the deposit now going on 

 seems to be, it is probably little, if any, more so than that which 

 went on in some parts of the Chalk series in the bed of the Chalk - 

 ocean over the old European area. Of the rate of the present de- 

 posit we know nothing. Is it even going on everywhere over the 

 deep Atlantic ? 



Therefore, although I think it highly probable that some con- 

 siderable portion of the deep sea-bed of the mid-Atlantic has conti- 

 nued submerged since the period of our Chalk, and although the 

 more adaptable forms of Hfe may have been transmitted in unbroken 

 succession through this channel, the immigrations of other and more 

 recent faunas may have so modified the old population, that the ori- 

 ginal chalk element is of no more importance than is the original 

 British element in our own English people. As well might it have 

 been said in the last century, that we were living in the period of 

 the early Britons because their descendants and language still lin- 

 gered in Cornwall, as that we are living in the Cretaceous period 

 because a few Cretaceous forms still linger in the deep Atlantic. 

 Period in geology must not be confounded with " system " or 

 " formation." The one is only relative, the other definite. A 



