VIII. On the Strata in the Neighbourhood of Bristol.

Abstract

An elevated ridge of land divides the vale of Bristol from the plain which is watered by the Severn. The parallel strata which compose this ridge rise towards the north-west at an angle of about 45° emerging from beneath the horizontal beds upon which the lower part of Bristol is built, and are afterwards broken off as they come in succession to the surface. At the base of the western escarpment of this ridge the lowest of the highly inclined strata abut with their broken edges against the horizontal beds of another formation, which there occupy the plain forming low hillocks almost to the Severn. The Avon passing through a precipitous ravine cuts all these strata almost at right angles to their planes, and exposes a section of them which may easily be observed, and has supplied me with the principal materials for the present paper. In the channel of the New River at Bristol a stratified red and yellow sandstone may be observed in strata nearly horizontal, but a little inclined to the north-west. The thickest of these strata are singularly divided into regular cubical or rhomboidal concretions, * the planes of which cut the planes of stratification at angles of about 45°. Some parts of this rock make a fine building stone, as may be seen in the docks, where the stonework is constructed of it. There is a number of small cavities in the sandstone filled with crystals of sulphate of strontian of a red or dull white