1. Introduction . That part of the River Wey which lies within the Wealden area may for convenience be divided into six sections; but it is almost entirely with the last three that the present paper is concerned. (See Pl. XXXVI.) Section I is a consequent river, cutting through the Chalk at Guildford, and is marked on Pl. XXXVI as ‘River Wey (Consequent).’ It is the only portion of the Wey that rises in the Weald Clay, its upper waters being mainly derived from a subsequent river running nearly parallel to the Lower Greensand escarpment. Section II is a subsequent stream flowing in from the east, parallel with the Chalk escarpment, and joining Section I at Shalford. It is described in Topley's ‘Geology of the Weald’ as the Tillingbourne. Section III is another subsequent river joining Section I from the west at Broadford. Between Godalming and Broadford its course is north-easterly, but from Tilford to Godalming its general direction is easterly, parallel to the Hog's Back, which lies about 3 miles to the north. This branch, which may for convenience be called the Godalming River, receives several tributaries from the south, some from Hindhead, others from the Lower Greensand ridge between Hindhead and Hascombe. The latter form notches in that ridge, and seem to have been reduced in length by the retreat of the Lower Greensand escarpment before branches of the River Arun, Some unimportant obsequent streams drain the Lower Greensand area to the north, between this river and the Hog's