The river-gorges here described are situated for the greater part in North Cornwall, between Boscastle and Tregardock, though a few occur in other parts of Cornwall and in Devon. Some of the characteristics of the coastal gorges of Devon have already been described by Dr. E. A. N. Arber, but there appear to be additional features in those of North Cornwall, which are possibly due to their mode of origin. These gorge-like valleys are more or less restricted to areas of peculiar topography, and their origin is connected with the history of that topography; while they form a sharp contrast with the valley-systems where such a topography does not exist. Thus, the valley-systems of Cornwall are divisible into two groups, each being marked by features peculiar to it; although in some cases the river-valley exemplifies the two types of scenery in different parts of itself. The difference is in part due to their respective stages of development, but mainly marks a renewal or rejuvenescence of the rivers' activity. The fall of these rivers near Tintagel averages 1 foot in every 13 feet. The Upland Plain. The gorges are incised in an upland plain, which truncates all hills at a uniform height of about 430 feet above the level of the sea, while the other series of valleys lies in an area diversified by many irregular hills and buried and submerged estuaries. This feature has become well-known in Cornwall through Clement Reid's descriptions. It is everywhere bounded landwards by a prominent