On the Jurassic Strata cut through by the South Wales Direct Line between Filton and Wootton Bassett

Publisher Website
Google Scholar
Abstract
I. Introduction. A paper like the following, dealing with a newly-exposed section, does not require any long introduction, and naturally the number of previous communications on the subject is limited. We know of only two, namely:—Mr. H. B. Woodward's account in the ‘Summary of Progress of the Geological Survey for 1898,‘ pp. 188-94, and the Rev. H. H. Winwood's Report on the Excursion of the Geologists’ Association to the new Great Western Railway-line from Wootton Bassett to Filton, Proc. Geol. Assoc. vol. xvii (1901) p. 144. II. The Liassic Sections West of Sodbury Tunnel. 1. The Main Section. ( a ) The White Lias. Resting directly upon a thin bed of typical Cotham Marble is a compact, cream-coloured limestone, about 1 foot thick; this bed forms a marked horizon, not only by reason of its peculiar texture, but also on account of the levelness of its surface. It represents the ‘White Lias’ of the Somerset area and, in particular, the ‘Sun-Bed’ of the Radstock district. ( b ) The Ostrea - and Torus -Beds. Immediately above the Sun-Bed is a series of limestones and subordinate shales, forming a total thickness of about 5 feet. Although no specimen of Psiloceras planorbis was found, the horizon of these beds is well marked zonally by Ammonites Johnstoni(=Amm. torus) , which is not uncommon in the upper strata. The series is, however, chiefly characterized by Ostrea liassica and its numerous mutations which abound throughout, but especially towards the base. The following is a complete list of the fossils that we

This publication has 0 references indexed in Scilit: