Mr. Taylor's Description, fcfr. 147 



which the little river Walkham flows, and near the point at which 

 it falls into the Tavy, a remarkable change of strata occurs ; the 

 side of a very abrupt hill, on the top of which is West Down, in 

 the parish of Whitchurch, is composed of a considerable cluster of 

 detached masses of granitic rocks, which are piled on each other 

 in the most picturesque manner, and form a lofty and steep bank 

 to the river. Killas occurs in the same hill, on each side, and is 

 the only rock observable on that which rises from the opposite edge 

 of the valley.* 



If we turn from the country on the east and north of Morwel 

 Down, to that on the west of it, we shall find that the Cornwall 

 side of the river Tamar is more diversified in the rocks that occur ; 

 killas generally prevails, but granite crowns the summit of Kithill, 

 which rises gradually from the banks of the river to the height of 

 1400 feet, and the same rock is to be found near the base of the 

 mountain, at Gunnis Lake Copper Mine, near New Bridge, and 

 again a little higher up the stream, at a place called the Clitter, a 

 provincial word, signifying a collection of loose masses of rock. 



The killas district is nearly surrounded on the three sides above 



* The situation of these rocks would point out a connexion between them and some of 

 the beds or veins of porphyry which are to be described as occurring in the tunnel through 

 Morwel Down ; the line of their direction would lead us to this point, and the inference 

 is strong that this is a part of one of them. It is however rather extraordinary that it 

 should have escaped notice in the deep valley of the Tavy, where it must pass, and where 

 I have little doubt it will be found from a recollection of the general features, though un- 

 fortunately it did not occur to me to look for it at the time when I could have done so. 

 It may likewise probably be traced through Morwel Down to Gunnis Lake Mine, which 

 is mentioned in the following paragraph. 



I do not venture to decide on what this rock should be called ; in describing the strata 

 of the tunnel I have assumed that it is porphyry. That which occurs in the Walkham 

 valley has much more the character of granite, and so I should incline to call it. 



The specimens will enable more competent judges to decide. 



