1851.] SEDGWICK — SLATE ROCKS OF DEVON AND CORNWALL. 11 



Cornish killas, but this fact is considered of no great importance. 

 Considered with reference to the section, they seem to be the newest 

 rocks of the coast. The section is to all appearance an ascending 

 section ; and we discovered no trace in the cliffs of any fault or break 

 of continuity ; still less did we find any apparent axis of elevation to 

 explain the appearance of a group older than the common Devonian 

 rocks. But the very rocks above-described strike through the 

 country towards the N.E. and come down to the coast a few miles 

 N. of the Dodman, near Gorran Haven; and in course of their range 

 several Cambrian fossils have been discovered in them by Mr. Peach. 

 The true position of these beds is, therefore, important ; and in con- 

 firmation of what has been just stated, I subjoin a section, by my 

 friend Mr. Whitley, through the same series of rocks to a point on 

 the coast a little east of Nare Head. (See fig. 1, p. 12.) 



In this section, the most northern portion seems exactly to repre- 

 sent the beds at the head of Gerrans Bay. The beds from the schistose 

 sandstone and quartzite to the end of the section are but a repetition 

 of the beds to the south of the great quartzite-band, which are seen 

 on the eastern coast of the bay above-described : nor have we here 

 any fault or break of continuity ; and the overlying rocks, near the 

 sea- cliff, seem to be the newest strata in Mr. Whitley's section. 



Leaving the sections near Nare Head (and taking no further note 

 of many interesting phsenomena, such as the protrusion of a boss of 

 serpentine on the east side of the headland), we passed along the 

 coast of Veryan Bay, and found at Forth Caerhays a coarse brown 

 greywacke, alternating with thick beds and masses of conglomerate. 

 Some of the conglomerates were coarse and contained pebbles and 

 concretions of limestone ; others were of finer texture, and, in some > 

 parts of the cliff, passed into coarse slate, and in others, into trap- 

 shale. Altogether the group nearly resembled some rocks we had 

 left behind ; the whole cliff was highly ferruginous, and the dip was 

 nearly in the same direction as before. 



From Caerhays we passed across the headland to Gorran Haven, 

 which is to the south of the remarkable quartzite-band above noticed. 

 The quartzite-band reaches a high part of the clifP called the Great 

 Cam, and a little further north is a cliff called the Great Feraver. 

 The dip of the beds is steadily towards a point about south-east by 

 south, and at a high angle ; and the same, or nearly the same dip is 

 continued towards the Dodman. Hence we might be led to con- 

 clude (as indeed I had done myself during a former visit in 1836) 

 that the rocks between Great Feraver and the Dodman were the 

 newest in that part of the Cornish coast. (See the south end of Section, 

 fig. 2, p. 12.) 



On the south side of Gorran Haven are alternations of finely lami- 

 nated slates with a ferruginous gritstone ; and the beds are frequently 

 disturbed and puckered, but have an average dip about magnetic south, 

 at an angle of 60° or 65°. On the north side are seen some beds of 

 coarse greywacke, of fine glossy dark slates, penetrated by innume- 

 rable quartz-veins, also of some singular concretionary masses, and 

 conglomerates. Fossils have been found in the more calcareous por- 



