Vol. 67.] DURING THE CRETACEOUS AND EOCENE PERIODS. 147 



unfossiliferous biscuit-coloured limestone of the Eastern Desert 

 with fossiliferous beds of Eocene age in the Western region was 

 interesting. He had found fragments of sea-urchins which seemed 

 to confirm the Authors theory as to the detrital origin of the 

 Eastern facies. He referred the Author to an early statement 

 made by him that the gypsum deposits of the lied Sea area were 

 altered Cretaceous, and asked him how he accounted for the fact 

 that, in places noted by the speaker in the Eastern Desert region, 

 the ' biscuit-coloured limestones ' apparently crop out from under 

 the gypsum series. 



Dr. Falconer said that he was interested to find in the paper the 

 suggestion of a possible unconformity between the Cretaceous and 

 the Eocene. In Northern Nigeria, where he had had an oppor- 

 tunity of working, there was a decided unconformity between the 

 Cretaceous and the Eocene, and he was inclined to believe that the 

 break at the close of the Cretaceous Period would ultimately be 

 found to have been more or less general throughout the Sudan. 



With regard to the photographs illustrating aeolian erosion, he 

 asked the Author whether or not he believed with Walther that 

 the formation of the cliffs and escarpments, as well as the sculpture 

 of their surface, should be assigned to the action of the wind. 

 Similar features in Nigeria were more readily explicable on the 

 assumption of fhiviatile erosion. 



Dr. A. P. Young welcomed the discovery of evidence clearly 

 indicating the relations of the Nubian Sandstone to definite stages 

 of the Lower and Middle Cretaceous. The range of the Nubian 

 Sandstone in depth seemed still to require elucidation. On account 

 of the easy solubility of the carbonate in both fresh and salt 

 water, the speaker was inclined to question the probability of an 

 important series of limestones being formed by mechanical trans- 

 portation of material derived from an older source. 



Dr. J. W. Evans enquired whether the Author had made any 

 comparison between the Cretaceous and Eocene of Egypt and the 

 strata of presumably similar age in Cyprus. 



Dr. A. S. Woodward referred to the fossil eel and fossil sole 

 exhibited by the Author from the Eocene of Tura, and remarked on 

 the extremely close resemblance between these fishes and their 

 existing representatives. 



Mr. A. E. Kitson was interested to find that the Author had proved 

 in Southern Egypt a gradual transition from the Cretaceous to the 

 Eocene. He himself had found in Southern Nigeria, between the 

 Niger and the Cross Rivers, that fossiliferous Cretaceous beds, having 

 a slight west-north-westerly dip, appeared to show a gradual transi- 

 tion from marine, through estuarine and lacustrine, into possibly 

 fluvio-lacustrine deposits. These were unconformably overlain by 

 Tertiary sands. Nearer to the Niger, and west of that river, fresh- 

 water deposits with beds of brown coal occurred ; while in other 

 •districts there were marine limestones, sandstones, shales, and clays. 

 Both groups were fossiliferous, normally almost horizontal, and 

 were probably of Eocene age. Field-evidence suggested no marked 



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