402 W. D. Lang — Lower Plienshachian of Charmouth. 



Survey Memoirs,' and may be summarized as follows: They extend 

 from Black Ven on the west to Seatown on the east ; traces only 

 appear on Black Ven ; the complete series occurs on Stonebarrow, 

 though there "only the lower portion is well-exposed"; their 

 thickness is about 100 feet, though variable, and as much as 125 feet 

 to the east of Golden Cap ; they consist of marly clays with 

 ' ferruginous bands ' and nodular limestones. Eight detailed sub- 

 divisions are given. 



Now this description in the Survey Memoirs, though excellent as 

 far as it goes, is not of much help for tracing the vertical distribution 

 of the ammonites or other fossils contained in the beds here described ; 

 the first step towards which is to be able to tell, when collecting 

 in any section, the exact position in the series of the bed whence the 

 specimens are being taken. For this it is necessary to know what 

 lithic characters are constant throughout the whole exposure of the 

 beds, and what are local accidents ; also how the thickness of the 

 whole series varies, so that measurements taken from the same bed at 

 different spots may be correlated. It is proposed to give the strati- 

 graphical results of some years' collecting, both as a guide to future 

 work and to supplement the descriptions in the Survey Memoirs. It 

 njay be here remarked that although adding to and even criticizing 

 the account in the Survey Memoirs, this further description would 

 never, probably, have been written without it ; and these new sub- 

 divisions are now put forward with full acknowledgment of the help 

 obtained from the publications of the Survey. 



It must be stated also that the following remarks do not include 

 the Green Ammonite Beds east of Golden Cap. From Golden Cap 

 to Seatown (where they are faulted away) ^ is about a mile, and 

 their total extent in the cliffs about four miles. It is therefore 

 possible that any apparent discrepancies in the Survey Memoir may 

 be due to observations made east of Golden Cap ; as is certainly the 

 case with the sandy beds recorded as appearing below the Three 

 Tiers, of which the author has not found more than traces, nor 

 these as a constant feature. Nevertheless, the similarity (except in 

 thickness) of the Green Ammonite Beds from Black Ven through 

 Stonebarrow to Golden Cap is so close that it would be surprising if 

 they changed considerably in that eastern mile. 



Three constant and more or less continuous limestones break the 

 monotony of the Green Ammonite clays (see Diagrams I and II). The 

 most conspicuous, continuous, and easilj^ recognized of these is the 

 Red Band. It is well known to the Charmouth fishermen, who, 

 when they want (for sale to visitors) a ' henleyi ' as they call 

 ammonites of the striatus group, go up Stonebarrow and pick away 

 at the Red Band. There can be no mistaking the curious pink-red 

 weathering of this muddy limestone. When fresh, it is hard and 

 firm ; but being only about 6 inches to a foot thick, it is generally 

 weathered nearly to the core, and is then grey - brown and in 



1 Woodward & Ussher, op. cit., 1911 ; and op. cit., 1906, 1st ed. ; H. B. 

 Woodward, The Lias of England and Wales (Mem. Geol. Surv. United. 

 Kingdom), 1893, p. 68. 



2 See H. B. Woodward, op. cit., 1893, p. 52, 



