X INTRODUCTION. 



On the west of Plymouth Sound the picturesque eminence of Maker 

 llei.u'hts rises from the water to a height of 402 feet, and on the east side 

 Staddon Heights attain between 300 and 400 feet. The flattest portion 

 of the country lies due east and south-east of Plymouth, where the lime- 

 stone has only an inconsiderable elevation, and beyond it are comparatively 

 low lands, forming a portion of the comitry known as the South Hams 

 and celebrated for its fertility. The coast line is extremely varied and 

 very beautiful, although not so bold as in some other parts of Devon and 

 Cornwall. However, at certain points it has features of grandeur, as by 

 Bigbury Bay below Kingston, and again where St. Germans Beacon rises 

 up from the shore of Whitsand Bay to a height of 513 feet.* 



Geology. Slates and associated Eocks. — By far the greater portion of 

 the rocks are Slates of varied character, intermixed with Shales and, 

 near the coast, some Red Sandstones. Here and there, in a comparatively 

 limited tract. Calcareous Slates appear associated with Crystalline 

 Limestone, the whole considered by most geologists to belong to the 

 Devonian or Old Red Sandstone group of rocks. " Though the identifi- 

 cation of the rocks of North and South Devon as of Old Red age is 

 generally accepted, the acceptance is by no means universal. There is no 

 question that these rocks are intermediate between the Silurian and the 

 upper part of the Carboniferous systems, but there has been much 

 question whether in truth they are really Devonian or Old Red Sandstone 

 at all, and whether they are not lower members of the Carboniferous 

 formation." {Worth, Trans. Plymoicth Institution, vol. v., p. 452.) t 



" The Devonian rocks, whatever view may be taken of their collective 

 position, are generally divided into three groups — Upper, jNIiddle, and 

 Lower— each of which has representatives on either side of the great 

 cuhniferous trough of the centre of the county [of Devon]. Origmally 

 the Plymouth rocks were classed as Lower Devonian, but they now rank 

 as Middle" (p. 453). We may place them under three subdivisions. " The 

 underlying slates and associated rocks ranging downwards from the 

 granite ; the limestones ; and the schistose and arenaceous beds ; the 

 whole forming an ascending scale m the order named" (p. 454). On the 

 confines of Dartmoor, around Horrabridge, Walkhampton, and Meavy, 

 the beds consist chiefly of pale greenish and grey argillaceous slates, 

 sometimes soft and silvery, and often veined with quartz. On the south 

 of Morwell Down the beds range from the Tamar by Tideford to the 

 north of Callington, and pass under higher beds south of the town. On 

 the south of Beer Ferrers and Bickleigh these green and grey slates pass 

 mider higher beds, which between Tamerton Foliot and St. Budeaux are 



* The elevations given in this work have been obtained either from the maps of the 

 Ordnance Survey, De la Beche's Report, or the readings of an aneroid. 



t In this Geological portion of the Introduction all the succeeding references to 

 pages simply, belong to this paper of Mr. "Worth's, in the Transactions of the Plymouth 

 InitUution. 



