GEOLOGY 



Bed I. Homogeneous whitey-brown sand, 'white rock,' unfossiliferous and without 

 current bedding. About 30 feet. 



Jukes-Browne ' agrees in Downes' conclusion that the beds 9 to i 

 inclusive have thinned out between Sidmouth and Haldon. 



The sections on the north side of Great Haldon'' give a total 

 thickness estimated at 66 feet, whilst total thicknesses exceeding 90 feet 

 have been recorded on Little Haldon.' The total maximum thickness 

 of the Selbornian in Devon is about 200 feet. 



Chalk. — The Lower Chalk as seen on the coast and in the outlier 

 between OfFwell and Widworthy * (east of Honiton) consists of cal- 

 careous sandstones (containing Ammonites mantelli, Pecten asper, etc.), 

 often very coarse and pebbly at the base, with an upper horizon of 

 quartziferous limestone with glauconitic grains containing Scaphites 

 cequalis, etc. The upper bed is sometimes absent. Jukes-Browne applies 

 the term Cenomanien to this arenaceous equivalent of the Chalk Marl. 

 The Lower Chalk of Membury is of a more ordinary type. The thick- 

 ness of these beds varies, being in part of the outlier east of Honiton 

 as much as 40 feet, of which the upper bed is only 2 feet. The Middle 

 Chalk consists of white chalk with many flints, the zone of Terebratulina 

 gracilis. It is about 80 feet thick in the coast near Beer, and forms the 

 upper 52 feet of the large Beer quarry. The lower zone of hard chalk 

 characterized by Rhynchonella cuvieri is about 40 feet thick on the coast. 

 It forms the lower part of the large quarry at Beer, of which the follow- 

 ing downward succession is given by Jukes-Browne : — 



feet 

 Hard compact yellowish limestone passing down into hard shelly chalk . 2 

 Rough yellowish nodular chalk with Inoceramus myti/oides, Rhynchonella 



cuvieriy etc 14^ 



Good crystalline freestone in several beds 13 



The Upper Chalk consists of chalk with many flints passing down 

 into hard nodular chalk (chalk rock). The upper part is characterized 

 as the zone of Micraster cortestudinarium, the lower part as the zone of 

 Holaster planus. A prominent black flint band has been taken as the 

 separating line at WhiteclifF. 



TERTIARY AND TERTIARY REMANliS 



The clay with flints and chert varies from a red-brown clay with 

 unworn and broken chalk flints, where it rests on the Chalk or in the 

 vicinity of Chalk outliers, to a yellowish-brown clay or loam with, or 

 without, broken chalk flints over, or mixed with, the chert fragments 

 where it rests on Greensand. The Rev. W. Downes ° noted that the 

 flinty clay on Blackdown, south of the latitude of Kentisbeare, capped 

 the cherty accumulation without admixture. Quartz grains are occa- 

 sionally met with in the clay, and any extraneous material, such as 



' Geol. Mag. July 1886, p. 225. * Ibid. p. 220. * Ibid. pp. 224, 225. 



* ^art. Joum. Geol, Soc. Aug. 1898, vol. liv. pp. 240-50. See also Woodward, Proc. Geol. 



Asioc. 1899, ^°-'' *"• P^' 3» PP- '3+' '3^~9- 



' ^art. Joum. Geol. Soc. Feb. 1882, p. 83. 



35 



