﻿part 1] EIVEE-GOEGES IN COENWALL AND DEVON. 69 



The accompanying sections (figs. 2 & 3, p. 68) show in profile 

 the way in which the fall has ripped out a chasm in the plateau 

 and also where it has cut a sharp V-shaped recent valley in its 

 ancient wider one. The country-rock is intensely metamorphosed 

 sericite-phyllite, which everywhere weathers into pyramidal stacks 

 and does not easily break down into gentle slopes. 



The Trevena or Tintagel Valley. 



The next valley presents similar features to the Rocky Valley, 

 hut the stream reaches the waterfall some 40 feet in 



height. The gorge is lined with rocks, some being volcanic, some 

 more massive dykes, and others phyllites. The stream is small, but 

 has a steep gradient and great cutting power. 



South of Trevena Valley the flat extends to Trebarwith, where 

 the same features are repeated, the rushing stream ripping for 

 itself a course through bare rock, and ending in a series of little 

 waterfalls and potholes near the shore, its ravine-like valley studded 

 with pinnacles and crags of bare rock bearing witness to the steep 

 gradient of the stream. At this locality the gorge has been cut to 

 sea-level, in part through schistose lava and asli, and near the sea 

 some instructive examples of miniature canons, cascades, and pot- 

 holes are preserved in these volcanic rocks. At Treligga the main 

 valley assumes a canon-like appearance ; but beyond Treligga the 

 sea has worn awa} r all traces of the plateau, and is bounded by 

 the ancient cliff -line. The upland plain reappears, however, near 

 St. Eval, some miles farther south, the feature having been cut in 

 rocks of different degrees of hardness, including the intensely- 

 resistant Staddon Grit. 



Inland, the plateau is well seen at Helland, near Bodmin, many 

 miles from the coast. But perhaps the most familiar examples 

 of it are those seen respectively at St. Agnes, where the Beacon 

 rises above the sand and clay-deposits that cover it ; at Land's 

 End, and also at the Lizard peninsula. It is conspicuous, too, in 

 the mining regions of Camborne and Redruth, on St. Austell 

 Moors, and near Lanhydrock. 



The Luxury an valley, famous alike for its beauty and for the 

 name that it has given to a peculiar rock, is an example of a gorge 

 incised in this plain. The plateau ends, at some 400 feet above 

 sea-level, as a notch, cutting the higher ground rising above it ; 

 and, moreover, this notch is also conspicuous in many of the huge 

 granite-boulders which lie scattered over the surface of the plain. 

 Several of these are upwards of 20 feet high, are rounded on 

 the top, but just above the level of the ground bear a wide basal 

 platform. The river flows through a wooded ravine nearly 100 feet 

 deep, the sides of which are sprinkled over with some big granite- 

 boulders that have rolled down from the plain as the river has 

 eroded its channel. The existence of this gorge is unsuspected 

 until its actual edge is approached, the surface of the adjacent 



