DANES' DIKE. 71 



and ascends to some height in the cliff, which at this place is between 

 seventy and eighty feet high. The beds of chalk rise to the north, and 

 as we pass along the shore, other lower and different layers come up in 

 succession, and expose a considerable number of fossils ; amongst which we 

 may notice sponges of many kinds, commonly called alcyonia, and others 

 referred by Mr. Mantell to his genus ventriculites, echini of the genera 

 ananchytes, and spatangus, marsupites ornatus, and apiocrinus ellipticus. 

 The marsupites are exceedingly abundant through a considerable thick- 

 ness of the beds which appear towards the Danes' Dike ; but the plates 

 are generally scattered, owing to the decay of their connecting membranes 

 before they were imbedded. The edges of the chalk layers are covered 

 by a quantity of subangular chalk rubble, or gravel, mixed with a few 

 rounded pebbles of other rocks : this is usually loose, but sometimes 

 hardened into a conglomerate, not unlike that of Stenkrith in West- 

 moreland. Above all lies the usual diluvial mass of clay, pebbles, and 

 sand ; from which occasionally fall huge blocks of gneiss and basalt. 



The Danish dike is an earthen rampart, running across the pro- 

 montory of Flamborough from one side to the other. The southern part 

 of this line follows the eastern side of a narrow and precipitous valley, 

 which enters the sea between cliffs one hundred and nine feet high. 

 At this place we obtain a clear proof of the high antiquity of vallies in 

 the solid strata : for here the strata of chalk are deeply excavated 

 beneath the mass of clay, and gravel, and sand, which was swept hither 

 by the force of the deluge. It is, therefore, not to be doubted, that such 

 hollows are at least as old as that period. What effects may have been 

 subsequently produced by the wearing of streams, the descent of rains, 

 the course of floods, or the bursting of lakes, the present coast furnishes 

 no sufficient data for discussing ; perhaps, too little attention has been 

 bestowed on this subject, since Dr. Hutton's general opinions on the 

 origin of vallies have been rejected. I think I am acquainted with 

 several instances clearly proving that in diluvial soils, and even in solid 

 strata, small vallies have been excavated by the streams which flow in 

 them, or else by postdiluvian floods. But after examining the re- 

 mainder of the section, and perusing the following descriptions, the 



