The Basic Intrusion of Bartestree, near Hereford.

Abstract

1. Introduction , and Field - Relations . The field-relations of the basic intrusion of Lowe's-Hill Quarry near Bartestree were fully described by Murchison, but, although the dyke has been several times mentioned by later geologists no detailed account has yet been given of its structure. The dyke is of considerable interest, both from its own character and from the alteration to which it gives rise in the Old Red Sandstone. It has a thickness of about 35 feet, and strikes in an east-north-easterly direction through the Old Red marls and sandstones which here lie almost horizontally. As represented in the 1-inch Geological-Survey map, the dyke has a length of about half a mile, striking across the road which leads southwestwards from Bartestree, and extending from about the middle of Tidnor Wood on the south-west to near Bartestree Convent on the north-east. At present, however, the only exposures are at Lowe's-Hill Quarry and for a short space immediately to the south-west. No trace of trap could be found west of the road; and, although fairly abundant débris occurs in Tidnor Wood, it appears to be derived entirely from Old-Red-Sandstone rocks. The Lowe's-Hill rock, though not now worked, has formerly been largely quarried; and a long cutting has resulted, the sides of which are formed by Old Red sandstone and marl, while the trap is exposed at the end. ( a ) North of the trap.—On the northern side of the cutting, an undulating line, fairly easily followed up the face of the cliff, marks the edge