Part of Gloucestershire and Somersetshire. 357 



III. NORTH-WEST OF SOMERSETSHIRE. 

 General Relations. 



§ 38. The north-west of Somersetshire, included between the Bristol Avon 

 on the north and the river Parret on the south, may be generally described as 

 composed of three ranges of hills, with intervening valleys, observing a direc- 

 tion nearly from east to west; — the Leigh Down, the Broadfield Down and 

 Dundry, and the Mendip range ; the first and second of these chains being 

 separated by the vale of the Avon, Ashton, and Nailsea, and the second and 

 third by that of the Yeo ; while on the south of the Mendip chain are found 

 the extended plains, through which flow the Axe, the Brue, and the Parret. 



This form of the surface has a near connexion with its geological structure, 

 which presents three great undulations from north to south, — though much 

 modified and interrupted, by abruption, the superposition of newer formations, 

 and partial denudation. These tracts, connected with the southern parts of 

 Gloucestershire, are in like manner composed of the first and second series 

 of the sedimentary class, and in part also of the third series. (See the Sec- 

 tion No. 5.*) My examination of them has been confined to the west of 

 a line drawn from the Bristol Avon through Stanton Drew, East Harptree, 

 Chewton Mendip, and Welis, to the river Parret. I now proceed to give the 

 results. 



§ 39. The general form of the western portion of Mendip may be thus 

 described. Its highest part, which includes Black Down, presents a smooth 

 uninterrupted surface, for a considerable way down either declivity on the 

 north and south : ravines then begin to appear, which in descending are 

 enlarged into defiles or combs. On the southern side, in particular, the range 

 is intersected by the deep defile of the Cheddar cliffs, which in ascending to 

 the north ramifies into those sinuous dells and ravines that mark the southern 

 face of Mendip. On the northern side appear the two deep combs of Bur- 

 rington and Dolborough ; — both enter Mendip nearly at right angles with the 

 vale of the Yeo, and both subsequently follow a course to the south of east, 

 almost parallel to the range, with a broken escarpment facing the south ; but 

 in ascending to the eastward they merge into the general surface. Into Bur- 

 rington comb, two ravines find their way, furrowing the northern face of 

 Mendip ; and, in like manner, a third ravine enters Dolborough comb, to the 

 east of the village of Roborough. But to the west of that meridian, the aspect 



* In this Section a few objects that do not stand immediately in the line, are projected upon 

 it. The highest part of Mendip is, according to the Ordnance Survey, 999 feet above the level 

 of the sea. 



