640 Professor Sedgwick and R. I. MurchisoNj Esq., on the 



the beautiful gorge down which the waters of Exmoor Forest descend to 

 Linton, very nearly represents the direction of the anticlinal. A great feature 

 like this may almost always be traced to some geological cause ; and we find 

 that the strata bordering on the gorge are nearly horizontal, while those to 

 the north and south of it continue for many miles to have a prevailing dip re- 

 spectively to the N.N.E. and S.S.W. The pommel of the saddle is not repre- 

 sented by a mere line, but by a broad space, within which the strata are nearly 

 horizontal, and on opposite sides of which their dip is not only reversed, but 

 greatly increased in quantity*. We may however state, with sufficient cor- 

 rectness, that the anticlinal line passes into the sea down the Valley of Rocks 

 immediately west of Linton : for to the south of it, the beds acquire a steady 

 southern dip ; and to the north of it, though their dip for some way is very 

 slight, a little beyond Linton they have, after some remarkable contortions, a 

 high northern pitch. It is in consequence of this anticlinal position, that 

 the coarse red arenaceous grey wacke of North Hill, and of the cliffs between 

 Porlock and Countesbury, is repeated over again, and occupies the whole suc- 

 cession of great red cliffs, extending from the west end of the Valley of Rocks 

 to Combe Martin f. Were we to draw two lines respectively from the Valley 

 of Rocks and Combe Martin, in the direction of the strike, we should nearly 

 define the range of the arenaceous system on the south side of the Lyne, as 

 far as Exmoor Forest; and thence the same system is traced (though not 

 without some interruptions) through the highest peaks of Somersetshire into 

 Croydon Hill. 



After the preceding statements, it must be obvious, that we class the gorge 

 of the Lyne among valleys of elevation. The causes, whatsoever they were, 

 which produced the anticlinal lines and regular strike of North Devon, acted 

 also, in the region just described, on the hard, brittle beds of red, arenaceous 

 grey wacke ; and thereby produced an enormous rupture along the line of con- 

 trary flexure, to which the present gorges of the Lyne owed their first origin J. 



This region illustrates also another point in geology: — when chains are 

 well-defined, the anticlinal lines are generally steady in their direction, and 

 nearly coincident with the strike of the beds ; but the end of a chain of hills, 



* See the north end of Section 1 (PI. LI.), from the Foreland near Linton to Dartmoor. f Ibid. 



^ Valleys of elevation (or, in other words, anticlinal lines traced through a country, not by 

 ridges but by depressions originating in a fracture of the strata) are by no means uncommon 

 among our older formations. They abound in the highest parts of North Wales ; and in Me- 

 rionethshire, an anticlinal line, about thirty miles long, is traced through its whole course by a suc- 

 cession of valleys. The actual pommel of the saddle (in the form of an anticlinal ridge) is only 

 seen in one single spot. 



