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Ch. XIV.] 



SEDIMENTARY DEPOSITION. 



807 



on the earth. At the same time it may enable him the better 



to 



intimate 



and Third Books of this work, one of which is occupied with 

 the changes of the inorganic, the latter with those of the 

 organic creation. 



pin 



laws which regulate 



the 



sider in this chapter, first, the 



deposition of sediment ; secondly, those which govern the 



mode 



movements 



Uniformity of change considered, first, in reference to sedi- 

 mentary deposition. — First, in regard to the laws governing 

 the deposition of new strata. If we survey the surface of 

 the globe we immediately perceive that it is divisible into 

 areas of deposition and non-deposition ; or, in other words, 

 at any given time there are spaces which are the recipi- 

 ents, others which are not the recipients, of sedimentary 

 matter. No new strata, for example, are thrown down on 

 dry land, which remains the same from year to year ; where- 

 as, in many parts of the bottom of seas and lakes, mud, 

 sand, and pebbles are annually spread out by rivers and cur- 

 rents. There are also great masses of limestone growing 

 in some seas, chiefly composed of corals and shells, or, as 

 in the depths of the Atlantic, of chalky mud made up of 

 foraminifera and diatomacese. 



As to the dry land, so far from being the receptacle of 

 fresh accessions of matter, it is exposed almost everywhere 

 to waste away. Forests may be as dense and lofty as those 



arm 



mould 



may 



myriads of trees, leaves, flowers, and fruits, those innumer- 

 able bones and skeletons of birds, quadrupeds, and reptiles, 

 which tenanted the fertile region. Should this land be at 



submerged, the waves of the sea may 



may me 



impart* a darker siiade ol colour to the next stratum of marl 

 sand, or other matter newly thrown down, 

 bottom of the ocean where no sediment is 



x 2 



So also at the 

 accumulating, 



