XLIII.—On the Physical Structure of Devonshire, and on the Subdivisions and Geological Relations of its older stratified Deposits, &c.

Plates L. to LVIII. PART I. Introduction. In a communication made to the British Association during its meeting at Bristol (1836), we first pointed out (by help of a section extending from the north coast of Devon to Dartmoor) the true geological position of the great culmiferous deposits, which occupy so large a portion of that county. In this paper our object is more extensive; for we not only attempt to describe the order of the successive formations north of Dartmoor, but also, as far as we are able, to bring them into comparison with the formations which are expanded from the south side of the Dartmoor granite to Start Point, and to the other headlands of the south coast of Devon, We believe that our present attempt is almost entirely new; for though some portions of the county have been described in considerable detail, yet the several parts have not been brought into any distinct comparison with one another; and in all the published geological maps, the greater part of the slate-rocks have been represented under one colour, without an attempt either to separate them into distinct formations or to mark their succession. Still less has any attempt been made to bring them into a strict geological comparison with the other mountain groups of England and Wales. Our present object is to exhibit a synopsis of the evidence by which the successive formations are determined. But in future and longer communications, we hope to lay more ample details before