The Stratigraphical Distribution of the Cornbrash : II. The North-Eastern Area

Publisher Website
Google Scholar
Abstract
I. I ntroduction I n a previous communication to the Society ( Douglas & Arkell, Part I, 1928 ) we gave a detailed account of the stratigraphical distribution of the Cornbrash in the South-West of England between Oxford and the Dorset coast, describing the more important features of the faunal sequence and giving our reasons for amending the list of brachiopod zones propounded by the late S. S. Buckman (1927, p. 10) . The present paper deals mainly with that part of the Cornbrash outcrop which lies between Oxford and the Humber, running through the counties of Oxfordshire, Buckinghamshire, Bedfordshire, Northamptonshire, and Lincolnshire. Preliminary observations on the outcrop in Yorkshire are also included, but the detailed investigation of that county has not yet been completed. Many of the conclusions arrived at during our study of the South-Western area have been strengthened or confirmed by discoveries made when following the outcrop farther north, and many new facts have come to light which show that our criticism of Buckman's clinal diagram (1927, p. 12), in which he sought to prove extensive penecontemporaneous erosion in the Cornbrash, was fully justified. As before, we have confined our attention chiefly to the brachiopod sequence, but it is hoped that the numerous ammonites collected will be dealt with at some future date. It may be recalled that the exact stratigraphical position of two of the suggested brachiopod zones—those of Tegulithyris bentleyi and Obovothyris stiltonensis, yet remained to be proved. The first-named (Zone 11) was placed by Buckman at the summit of