546 Mr. Scrope on the Ripple-Marks in the Forest Marble. 



the ocean were beating against a line of coast now in the centre 

 of our island. We see a succession of sedimentary deposits, 

 consisting of clayey and calcareous mud, wrinkled on the sur- 

 face by the waves, exactly after the manner of the sandy shores 

 of our actual coasts; and, like them, having this surface strewed 

 with small fragments of the shells then existing, of corals, 

 encrinites, spines of echinus, and Crustacea ; blackened, occa- 

 sionally, with carbonized vegetable remains, and intersected by 

 the fresh tracks of some animal which has been actively pur- 

 suing its prey or disporting upon it. Layer upon layer was 

 deposited, with these characters, for a considerable thickness, 

 till a change took place ; not, however, suddenly, but by a 

 gradual increase in the quantities of sand, clay, or calcareous 

 matter, till the deposit of the forest marble was succeeded by 

 the thicker beds of sand and gritstone, of clay, and then of 

 rubbly limestone or cornbrash. 



If the ripple-marks and foot-tracks are allowed to attest the 

 local coast line of the emerged lands at the date of their forma- 

 tion, it will become very doubtful whether these beds were ever 

 in those situations covered by the newer, or, as we call them, 

 the superior deposits. If they were, there must have occurred 

 a considerable subsidence in the interval ; but until the ripple- 

 marks, &c. are found at a great depth below existing marine 

 strata, it will be allowable to doubt such alternations of sub- 

 mersion and emersion, and to believe that we have in these 

 beds the last deposits of the sea in that locality, and that the 

 coast line since that period has been progressively shifting 

 eastwards, by the gradual elevation of the island, and the 

 annexation of new littoral deposits. 



At all events, it appears to me, that the further examination 

 of these marks may prove highly useful, by throwing light on 

 some of the most interesting, and, at this moment, most agi- 

 tated questions in geology, namely, the probable outline of the 

 elevated or emerged lands at the date of the several marine 

 formations the problems as to their alternate subsidences 

 and elevations and the analogy, in every point of view, of the 

 oceanic deposits of early date with those which are forming at 

 present on the existing shores, or at the bottom of the sea. 



March 2, 1831, 



