32 



TMI-: PAST CONDITION 



than the force of the current is strong enough to convey 

 i lu linest dtbris, will, of course, receive no more 

 UK! having attained a certain thickness, will 

 now grow no thicker. 



We should he misled in taking the thickness of that layer, 

 whenever it may be exposed to our view, as a record of time 

 in the manner in which we are now regarding this subject, 

 as it would give us only an imperfect and partial record : 

 it would seem to represent too short a period of time. 



Suppose, on the other hand, that the land (C D) had 

 gone on rising slowly and gradually say an inch or two 

 inches in the course of a century, what would be the 

 practical effect of that movement ? Why, that the sedi- 

 ment A and B which has been already deposited, would 



eventually be brought nearer to the shore-level, and again 

 subjected to the wear and tear of the sea ; and directly 

 the sea begins to act upon it, it would of course soon 

 cut up and carry it away, to a greater or less extent, to 

 be re-deposited further out. 



Well, as there is, in all probability, not one single spot 

 on the whole surface of the earth, which has not been up 

 and down in this way a great many times, it follows that 

 the thickness of the deposits formed at any particular spot 

 r;mnot be taken (even supposing we had at first obtained 

 t <l;ita as to the rate at which they took place) as 

 affording reliable information as to the period of time 

 occupied in ils deposit. So that you see it is absolutely 

 from these facts, seeing that our record entirely 

 consists of accumulations of mud, superimposed one on 

 the other ; seeing in the next place that any particular 

 spots on whu-h accumulations have occurred, have been 

 constantly moving up and down, and sometimes out of 



