336 REPORT— 1888, 



out upwards and the remainder of the clay generally forms a solid mass, 

 broken only by the occurrence here and there of irregular pockets of 

 sand, gravel, and clay that seem to have been caught up and included 

 in it. This inclusion of other beds is its most characteristic feature, 

 and one that is sure to be found wherever the clay can be traced for 

 any distance. In the neighbourhood of our section these patches are of 

 chalk-rubble or of clayey silt and sand ; but further east on the headland, 

 near the lighthouses, the lowest boulder clay (almost certainly this Basement 

 clay) includes transported masses of Speeton clay mixed with some red 

 chalk, while at Bridlington Qnay and elsewhere some of the patches of clay 

 and sand which it encircles are richly fossiliferous, and form the deposit 

 long known as 'the Bridlington Crag.' These shelly patches contain a 

 peculiarly Arctic molluscan fauna of great richness and variety, and are the 

 fragments of an old sea-bottom formed under extremely glacial conditions. 



Until the exposures of last spring the continuity of this shelly Base- 

 ment clay with the boulder clay covering the Cliff-beds was extremely 

 doubtful, and the writer was inclined to believe, for reasons that will 

 presently be given, that the Basement clay was not represented in oar 

 section, or was represented only Vjy the chalk-rubble, but the new 

 evidence has determined this point. 



The upper limit of the Basement clay in our section is well marked by 

 a thin seam of fine shingle and sand about four inches thick. This part- 

 ing, though here so slight, if followed southward for a few hundred yards, 

 is found to develop into a thick bed of finely laminated elastic clay with 

 a seam of fine gravel above and below it, that forms for some distance a 

 ■well-marked horizon. 



This laminated clay contains no organic remains and no pebbles. It 

 seems to have been accumulated in the hollows of an uneven surface of 

 the Basement clay, and is not found much above high-water mark. 



The Purple Clay. — Next in the Sewei'by section comes a thick homo- 

 geneous mass (18 feet) of tough brownish-coloured boulder clay that 

 is rather more stony than the Basement clay, and not so earthy in texture. 

 No dividing line has been found in it in this section ; but if the clay be 

 followed southward for a short distance, it is found to split into an upper 

 and a lower division that are separated by the intervention of a variable 

 bed of sand and gravel that often shows contortions, and this division 

 may be traced through the greater part of Holdemess. 



It was the absence of this line, and the consequent presence of only 

 two beds of boulder clay over the chalk, instead of the three seen so well 

 at Bridlington Quay, that led the writer and others to doubt whether the 

 Basement clay passed up over the chalk in the cliff. 



The Sewerby Gravel. — A well stratified bed of chalky gravel 10 feet 

 thick caps the section, and may be traced southward along the cliff-top 

 nearly to Bridlington Quay. 



This is known as the Sewerby Gravel, and, though rather newer than 

 the boulder clays, it probably dates back to the time when the ice was 

 retreating, and can scarcely be called Post-GIacial. But through it a 

 passage to more recent times may be traced, by way of certain low-level 

 gravels of fresh- water origin with which it seems to be connected near 

 Bridlington Quay, and which in turn lead up to the fresh- water marls that 

 lie in the hollows on either side of the town, whose formation has probably 

 gone on till comparatively recent times. 



Age of the Buried Cliff-beds. — In your reporter's communication to 



