Guide to the Geology of London and the Neighbourhood (An Explanation of the Geological Survey Map of “London and its Environs,” and of the Geological Model of London, in the Museum of Practical Geology)

Abstract

SINCE the appearance of the second edition of this most useful little work, some valuable additions have been made to our knowledge of the rocks which underlie the London Basin. The deep borings at Turnford, near Cheshunt, and at Ware, which were executed by the New River Company in 1879, have furnished new data to geologists for determining the position and characters of that great underground ridge of palaeozoic rocks, the probable existence of which was so long ago indicated by Mr. Godwin-Austen. This underground ridge of palaeozoic rocks has now been reached in no less than six borings, those of Kentish Town, Harwich, Crossness, Meux's Brewery, Turnford, and Ware. In four of these cases the age of the rocks which have been found unconformably underlying the Cretaceous strata is placed beyond question, by the discovery of the well-preserved and characteristic fossils, lists of which have recently been published by Mr. Etheridge. At Harwich the cores of dark-coloured indurated shale yielded Posidoniæ, which proved that the rock belongs to the lowest part of the Carboniferous system; at Meux' s Brewery and at Turnford the purple shales yielded the characteristic fossils of the Upper Devonian; while at Ware cores were brought up crowded with the well-known fossils of the Wenlock shale.