ERA OT THE CRETACEOUS FORMATION. 61 



quihy covered up by sands replete with marine exuviae."* 

 A subsequent depression of the same area, to the depth of 

 at least three hundred fathoms, is believed to have taken 

 place, to admit of the deposition, of the cretaceous beds 

 lying above. 



From the scattered way in which remains of the larger 

 terrestrial animals occur in the Wealden, in the intermix- 

 ture of pebbles of the special appearance of those worn in 

 rivers, it is also inferred that the estuary which once co- 

 vered the southeast part of England was the mouth of a 

 river of that far descending class of which the Mississippi 

 and Amazon are examples. "What part of the earth's sur- 

 face presented the dry land through which that and other 

 similar rivers flowed, no one can tell for ceriatn. It has 

 been surmised, that the particular one here spoken of may 

 have flowed from a point not nearer than the site of the 

 present Newfoundland. Professor Phillips has suggested, 

 from the analogy of the mineral composition, that anciently 

 elevated coal strata may have composed the dry land from 

 which the sandy matters of these strata were washed. 

 Such a deposite as the Wealden almost necessarily implies 

 a local not a general condition ; yet it has been thought 

 that similar strata and remains exist in the Pays de Bray, 

 near Beauvais. This leads to the supposition that there 

 may have been, in that age, a series of river-receiving 

 estauries along the border of some such great ocean as the 

 Atlantic, of which that of modern Sussex is only an 

 example. 



ERA OF THE CRETACEOUS FORMATION. 



The record of this period consists of a series of strata, 

 in which chalk beds make a conspicuous appearance, and 

 which is therefore called the cretaceous system or forma- 

 tion. In England, a long stripe, extending from York* 

 shire to Kent, presents the cretaceous beds upon the sur 

 face, generally lying conformably upon the oolite, and in 

 many instances rising into bold escarpments towards the 

 west. The celebrated cliffs of Dover are of this formation. 

 It extends into northern France, and thence north-west- 

 ward into Germany, whence it is traced into Scandinavia 



•* I>e la Beche's Geological Researches, p. 344. 



