■ ^ Of 



t s 



fillaceo 



H8 



ii 



-::of 



» piih- s^^™, 



* or perkp' 



rivci onlj 



»,., 



h*» are eiirlit 



• 'Tti 



ancient 



innel of ^■ 

 ji leiiirtli, it 



uflif 



of river- 



^ at aDotbef 

 ,f those part' 

 «lt 



^ter not 





(see 



Vol- 



^ at 'f 



OVt-' 





Ch. XLVIIL] 



IN SUBAQUEOUS STEATA. 



571 



occasioned by siicli alternate elevation and depression as lias 

 occurred in modern times in the delta of the Indus. ^ But 

 the subterranean movements affect but a small number of 

 the deltas formed at one period on the globe ; whereas the 

 siltino- up of some of the arms of great rivers and the opening 

 of others, and the consequent variation of the points where the 

 chief volume of their waters is discharged into the sea, are 

 phenomena common to almost every delta. 



The variety of species of Testacea contained in the recent 

 (-nlrareous marl of Scotland, before mentioned, is very small. 



but the abundance of individuals 



rniely 



a cir- 



cumstance very characteristic of freshwater formations 



compared to marine 



bottom 



by dredging, wherever the individual shells are exceedingly 



numerous 



IMBEDDING OF THE REMAINS OF MARINE PLANTS AND 



ANIMALS. 



Marine 



plants. — The large banks of drift sea-weed which 

 occur on each side of the equator in the Atlantic, Pacific, and 

 Indian oceans, were before alluded to.f These, when they 

 snbside^ may often produce considerable beds of vegetable 



matter. 



Holland, snb-marine 



from sea- wrack 



may 



form im 



mud 



texture. 



Sea-weeds are often cast up in sucli abundance on our shores 

 during lieavy gales^ tliat we cannot doubt that occasionally 

 vast numbers of tbem are embedded in littoral deposits now 



m progress 



We learn from 



common 



the materials of coal, the Algae must give rise to im 

 chemical chanijes in the comDOsition of strata in whi* 



imbedded 



These plants always contain sulphuric acid 



* Page 99. 



t Page 392. 



