36 THE PAST CONDITION 



Now you must not suppose that I put this before you 



for the purpose of raising a paradoxical difficulty ; the 



. >. that the great mass of deposits have taken place 



! bottoms which are gradually sinking, and have been 



formed under the very conditions I am here supposing. 



Do not run away with the notion that this subverts 

 tlu' principle I laid down at first. The error lies in extending 

 a principle which is perfectly applicable to deposits in 

 the same vertical line to deposits which are not in that 

 relation to one another. 



It is in consequence of circumstances of this kind, and 

 of others that I might mention to you, that our conclusions 

 on and interpretations of the record are really and strictly 

 only valid so long as we confine ourselves to one vertical 

 section. I do not mean to tell you that there are no 

 qualifying circumstances, so that, even in very considerable 

 areas, we may safely speak of conformably superimposed 

 beds being older or younger than others at many different 

 points. But we can never be quite sure in coming to that 

 conclusion, and especially we cannot be sure if there is any 

 break in their continuity, or any very great distance between 

 the points to be compared. 



Well now, so much for the record itself, so much for 

 its imperfections, so much for the conditions to be 

 observed in interpreting it, and its chronological indications, 

 the moment we pass beyond the limits of a vertical linear 

 section. 



Now let us pass from the record to that which it contains, 

 from the book itself to the writing and the figures on its 

 pages. This writing and these figures consist of remains 

 of animals and plants which, in the great majority of cases, 

 lived and died in the very spot in which we now find 

 them, or at least in the immediate vicinity. You must 

 all of you be aware and I referred to the fact in my last 

 lecture that there are vast numbers of creatures living 

 at (he bottom of the sea. These creatures, like all others, 

 sooner or later die, and their shells and hard parts lie 

 nt the bottom; and then the fine mud which is being 

 .in My brought down by rivers and the action of the 

 and tear of the sea, covers them over and protects 

 them from any further change or alteration; and, of 

 course, as in process of time the mud becomes hardened 

 an<l solidified, the shells of these animals are preserved 

 and firmly imbedded in the limestone or sandstone which 



