Vol. 60.] LniESIOXE AT BARNWELL. 363 



Barnwell. This, with the knowledge that the Gault as a whole is 

 thinning northward and passes into the Red Chalk of Hunstanton, 

 further complicates the problem of the Cambridge Greensand ; 

 but into that problem I cannot enter here. 



In conclusion, I gladly express my thanks to Mr. R. H. Eastall, 

 of Christ's College, for help in collecting the fossils here recorded; 

 also to Mr. H. Woods and Mr. A. J. Jukes-Browne, of St. John's 

 College, for encouragement and aid in the identification of some of 

 the species. 



Discussion. 



The President welcomed the Author's first paper to the Society, 

 which he hoped and believed would be followed by many others. 

 He thought that the Upper-Gault age of these beds was proved by 

 the fossils. Mr. Jukes-Browne, who had done so much work in 

 this district, seemed to speak with great caution as to the absence 

 of Upper Gault in Cambridgeshire. The speaker was inclined to 

 think that the deposit would prove to be local in the county, having 

 been removed elsewhere by denudation not necessarily indicating 

 upheaval, but rather the local action of eroding marine currents. 



The Rev. J. F. Blake agreed that the ammonite-fauna exhibited 

 consisted essentially of Upper-Gault forms ; and these being found 

 below some 40 feet of Gault-material, proved that the Upper Gault 

 had not been removed from the area. These beds had not been 

 noticed by earlier writers, from the fact that they had never been 

 exposed ; there never had been 40 feet of Gault exposed in any 

 working below the coprolite-bed. The fossils exhibited were 

 markedly distinct from those of the ' Cambridge Greensand \ The 

 latter could not have been derived from them ; and their presence 

 at this depth threw doubt upon their ever having been reached by 

 denudation anywhere in the district. 



The Author thanked the Fellows for their reception of his paper. 

 In reply to the suggestion that the Upper Gault of Barnwell was 

 merely a local ridge which had escaped erosion during the formation 

 of the 'Cambridge Greensand', he pointed out (1) that the total 

 thickness of Upper and Lower Gault at Barnwell was less than that 

 shown in any of the well-sections south of Cambridge : (2) that the 

 yield of phosphate-nodules and fossils from the former coprolite- 

 workings on the site of the present Gault-pit at Barnwell was 

 large, and that the ' derived ' fauna contained therein included 

 Lower as well as Upper-Gault forms ; and (3) that the Gault-pits 

 at Barrington and Arlesey which showed the junction of Gault and 

 Chalk-Marl yielded numerous Upper-Gault lamellibranchs, and that a 

 weD-section at the latter place had proved the existence of a ' Hard 

 Band ' like that at Barnwell, but at an even greater depth. 



2b2 



