﻿Yol. 6 1.] PHOSPHATIC CHALK OF TAPLOW. 463 



The Taplow-Court section was visited by the Geologists' Associa- 

 tion in July of that year, but the Report x of the excursion, so far 

 as it relates to the Phosphatic Beds, consists almost entirely of 

 extracts from the last-mentioned essay. It is evident, however, 

 from the character of the material collected by the present writers, 

 quite independently, on that occasion, that the attention of the 

 party was mainly directed to the higher phosphatic band. A 

 sample of Chalk from this horizon was sent by one of us to 

 Mr. F. Chapman, who, later in the same year, published a lengthy 

 list of foraminifera obtained therefrom. 2 



Between the years 1892 and 1904 no fresh information relative 

 to this section seems to have been published, 3 though a good deal of 

 desultory fossil-collecting was carried on by occasional visitors. 

 In the meantime, great progress was made in zoning the Upper 

 Chalk of the southern parts of this country by Drs. Howe & 

 Blackmore, and Messrs. Brydone, Griffith, Jukes-Browne, W. Hill, 

 Sherborn, and others ; and two results of this work having an 

 important bearing on the age of the Taplow phosphates were 



(1) the establishment of a definite line of demarcation between the 

 zones of Actinocamax (Belemnitella) quadratus and Marsupites, and 



(2) the recognition that the true Actinocamax quadratus (Defrance) 

 rarely or never occurs below its own zone. At this stage, therefore, 

 the student with no other evidence before him than that afforded 

 by the literature of the subject, might reasonably have inferred that 

 the Taplow Chalk, with its abundant Actinocamax quadratus, 

 belonged to a distinctly higher horizon than the Margate Chalk. 

 That such was the view taken by French geologists may be 

 gathered from the fact that Prof. A. de Lapparent, in the third edition 

 of his '• Traite de Geologie ' (1900), places the ' Craie phosphatee de 

 Taplow ' in the Campanian stage, between the ' Craie de Norwich ' 

 and the (Santonian) ' Craie de Margate.' 4 



In the early part of 1904, however, there appeared the third 

 volume of Mr. Jukes-Browne's memoir on ' The Cretaceous 

 Bocks of Britain,' containing some remarks on the Taplow Chalk 

 which, while they cast a grave doubt on the correctness of this 

 inference, are well calculated to reawaken an interest in that rock. 

 The passages in this work which deal directly with the deposit 

 contain no reference to the occurrence of Actinocamax quadratus, 6 

 the place occupied by that species in previous accounts being taken 

 by A. granulatus (Blaiuville) — a form which ranges down into the 

 Micraster cor-anguinum-Zone. No reason is given for this important 



1 By the late J. II. Blake, Proc. Geol. Assoc, vol. xii (1892) pp. 406-408. 



2 ' Microzoa from the Phosphatic Chalk of Taplow' Quart. Journ. Geol. 

 Soc. vol. xlviii (1892) pp. 514-18. 



3 The Phosphatic Peds are discussed by Dr. W. Fraser Hume, Proc. Geol. 

 Assoc, vol. xiii (1891) pp. 238-39, and compared with those of Southerham by 

 Messrs. Strahan & Chapmau, Quart. Journ. Geol. Soc. vol. lii (1896) pp. 463-72. 

 See also the second footnote on p. 486 of this paper. 



4 Tableau, pp. 1406-1407. 



5 The mention of this species on p. 376 is probably a clerical error. 



