(part 4] JURASSIC chrojs-ology. . 429 



Now, Bothenhampton is some 7 miles from the main anticlinal 

 .axis of the Weymouth Anticline. If it be a legitimate sm-mise that 

 the conditions producing Alpenkalk extended as far south of the 

 .axis of the anticline as the}'' do north of it, then a north-to-south 

 .stretch of the White Bed was some 14 miles. To put the east-to- 

 west stretch at the same distance would be reasonable : this would 

 give nearly 200 square miles of area as the original extent of 

 White-Bed deposit. To put the east- to-west stretch at some three 

 times the distance would not be reall}^ so very unreasonable : this 

 would imply some 600 square miles of area — by no means an incon- 

 siderable extent. 



The exploration north of Bridport of what is marked as the 

 contact-line between Lias Marlstone (G 2) and Lias Sand (Gr4) 

 would certainly be desirable, as giving a chance of finding further 

 ■evidence of the Yeovilian White Bed. But there is little chance 

 ■of exploration in such an area giving more evidence for the Burton 

 White Bed, as there are plenty of quarries opened at the necessary 

 horizon and they have received much attention. However large 

 ma}^ have been the surface over which the Burton White Bed was 

 deposited, it seems unforfcunatel}^ to be only too true that it has 

 been wholly removed from all that area. If such removal did 

 not wholly take place, as at Burton Bradstock, prior to the 

 deposition of the Garantiana Bed, it was accomplished later, when 

 it shared the fate which in some localities was meted out to 

 the Garantiana or subsequent deposits. But there is reason to 

 suppose that the main accomplishment of its destruction was a 

 ;pre-(x«^•«;^^'^V^i/i« episode, for, unlike the strata of nioriense date 

 which are preserved only at a few isolated localities, the strata of 

 Garantiana date have a remarkably wide sj^read. 



An observation made at the Black Bocks, west of West Bay, tends 

 to confirm the theory that the White Bed was an original stratified 

 ■deposit, broken up and redeposited later, where it was not preserved 

 by being let down in the fault. At the Black Rocks, about the 

 middle, close to the beach of pebbles, was found a big block (dia- 

 gram 12, p. 430) — 4 feet long, 18 inches broad and 26 inches thick 

 — consisting of the Astarte-^Q(\. (^Garantiana) matrix, recog- 

 nizable by its lithic characters and the great number of various 

 fossils shown in section. About in its middle it carries a large 

 mass (1 foot thick), extending rather beyond the length and 

 breadth of the block, because of its superior hardness. This mass 

 is a very compact, close-grained, grey rock, apparently quite un- 

 fossiliferous. It differs from all other local Inferior- Oolite rocks 

 •except the White Bed ; that it resembles in texture, hardness, and 

 paucity (if not absence) of fossils. In colour it differs some- 

 what, but not more, perhaps, than the difference of locality — 

 it is nearly 2| miles from the Burton White Bed — might explain. 

 It certainly seems as if this included mass might be a local 

 portion of the White or Nautilus Bed redeposited in the Astarte 

 Bed. If such be the case, then, as the Black Ilocks lie at the 

 foot of Watton Cliff, we should have evidence of the second 

 White Bed deposited in the same locality as the first. 



2 G 2 



