OKMEROB T ALLEY OF THE TEIGX. 



419 



fragments from that formation have been noticed by me along its 

 course. 



The point of the Mil between the North and South Teigus, at their 

 junction at Leigh Bridge, faces up stream, and is covered by large 

 masses of granite piled on each other ; near this place, on a spur from 

 the hill on the right of the Teign, is the Puckie Stone, a transported 

 block of granite about 26 feet long, 8 feet 8 inches wide, varying in 

 height from 8 to 10 feet, rounded at the ends and angles, and hav- 

 ing on the top a rock-basin ; it rests on other transported blocks, and 

 is broken obhquely across the centre. 



On the right, a short distance below Chagford, the Teign is joined 

 by Week Brook, having Yellum on its left bank : Bughead is on the 

 ridge between this and a parallel valley which extends from the Teign 

 at Whiddon Park to the range, near !Moreton Hampstead, that di- 

 vides the watershed of the Teign and the Bovey Brook. The course 

 of the Teign and the feeders that have been mentioned, with the 

 exception of a small area on the upper part of one of the branches 

 of Blackatton water, is entirely over granite ; and the gravels found, 

 both in these streams and in the tin-grounds, as well as the " con- 

 tour " or surface gravels, and those considered to have been deposited 

 before the reexcavation of these valleys, and here called " Old Gravel," 

 down to the place where the Easter Brook joins the Teign near Do- 

 gamarsh Bridge, are composed of granite or granitoid rocks. 



The upper part of the valley of the Easter Brook, and the summit 

 of the greater part of the high ground to the left of that valley, are 

 composed of Carboniferous rocks ; and near Parford a vein of por- 

 phyry is seen ; and the gravels in the streams and tin-grounds are 

 of granite and Carboniferous rocks, a few fragments of porphyry 

 occurring with them in the lower part of the valley. The " Old 

 Gravel " is of granite or granitoid rock. After the junction of the 

 Easter Brook and the Teign, fragments of Carboniferous rocks are 

 mixed with those of granite, both in the river-gravel and in the 

 tin-grounds. The next parallel and adjacent valley to the north, 

 that of the Silkhouse Brook and Drewsteignton, is in Carboniferous 

 there found. The Teign leaves the granite for the Carboniferous 

 strata at a gorge between Hunt's Tor and "Wliiddon Park, and runs 

 over that formation by Einglebridge (where it receives the Silkhouse 

 Brook), Clifford Bridge, and Dunsford Bridge to Chudleigh Bridge, 

 near which place it enters on the Miocene beds of the Bovey Clay. 



The Bovey Brook flows over the granite until it enters on the 

 Cai^boniferous rocks near Letford Bridge, where it receives the Wray 

 Brook, which also down to that place has flowed over the granite ; 

 near Bovey Tracey the joint stream enters on the Bovey Clay. 



The granite of the Dartmoor district is stated by Sir Henry De 

 la Beche* to be of more recent date than the Carboniferous rocks; and 

 Mr, Yicary and Mr, Pengelly have shown the existence of pebbles 

 of granite in the Xew Bed Sandstone at Xorth Tawton, Sampford 



* Report on the Geology of Cornwall, Deyon, &c., p. 116. 



