﻿464 MESSES. WHITE AND TREACHEK ON THE [Aug. I905, 



change, and we are left to infer that the earlier determination of 

 the Taplow belemnoid was incorrect. 



With regard to the Chalk itself, it is observed : — 



' JFossils are very scarce in the lower part of the section, but Mr. Rhodes [the 

 fossil-collector to the Geological Survey] obtained Galerites albogalerus near 

 the bottom. As no plates of Marsupites were found, it is doubtful whether 

 any part of the section is referable to the zone of Marsupites, and it certainly 

 cannot belong to the zone of Actinocamax quadratus.' x 



Mr. Jukes-Browne thinks that it is ' in all probability equivalent 

 to the \_M. cor-anyuinw}i] Chalk of Cliffe and Gravesend,' in Kent 

 {op. cit. p. 207). 



The foregoing outline of former work on the Taplow Phosphatic 

 Chalk will serve to demonstrate the desirability of a thorough 

 examination of the Lodge section. We have there a group of 

 beds, less than 70 feet thick, referred, directly or by implication, 

 to three distinct zones of the Upper Chalk (the thinnest of which 

 commonly exceeds 100 feet in this country 2 ), mainly on the 

 evidence of six fossil species, not one of which — so far as can be 

 gathered from the published descriptions — is really diagnostic. 3 

 The conclusions derivable from data so scanty and imperfect are 

 of little value ; and, in the absence of more definite evidence, the 

 safest course appears to be that taken by Mr. Jukes-Browne, who 

 refers the beds, provisionally, to the zone of Micraster cor-anguinum, 

 which is known to contain all the fossils so far recorded from 

 them, and to include the higher part of the Chalk of much of the 

 surrounding country. 



II. Description of the Beds. 



The position and surroundings of the long-abandoned quarry 

 showing the Phosphatic Chalk above mentioned may be indicated 

 in a few words. It is situated on the left bank of the Thames, at 

 the southern end of the steep, wooded river-scarp, or bluff, which 

 forms the western side of the spur supporting the village of Taplow, 

 in Buckinghamshire. The higher part of this spur, the summit of 

 which lies between 120 and 150 feet above the river, consists of an 

 outlier of the Beading Beds, capped with gravel, extensive spreads of 

 which, and of finer alluvial drift, also envelop the adjoining lower 

 ground on the west, south, and south-east. To the north-west, 

 on the farther side of the Thames Valley, extend the Chalk up- 

 lands of the Chilterns, bearing other Eocene outliers ; while to the 

 south, east, and north, at distances of 1| to 2| miles, the main 



1 < The Upper Chalk of England' Mem. Geol. Surv. 1904, p. 220. 



2 See vertical sections, ibid. fig. 79, p. 446. 



3 It was not until our work was well advanced that we obtained, by the 

 kindness of Mr. H. A. Allen, the following list of fossils from this pit in the 

 Geological-Survey collection, at Jermyn Street: — Echinocorys scutatus,~Leske, var. 

 pyramidatus ; Ostrea acutirostris, Nilss. (? O. Wegmanniana, d'Orb.); Inoceramus ; 

 Actinocamax granulatus (Blainv„). 



