1867.] IIACKESTTOSH CUETATURE OF SLATY LAMIXJE. 325 



rous sections exposed in the mineral-railway- cuttings near Ealeigh's 

 Cross, on the summit of Brendon Hill. Here the hending and 

 curving back of the slates is seen to prevail over a large area, with 

 a uniform direction nearly S.S.E.* The laminae in many places are 

 much broken, and shattered to a considerable depth ; but still the 

 line of separation between the bent masses and the slates m situ 

 can generally be traced. The most important fact in connexion 

 with these sections is this : — tlie bending and curving-hacJc over ex- 

 tensive areas has tah en place on perfectly level ground, with a depres- 

 sion instead of an elevation on the side whence the movement must 

 have come. There are, indeed, instances in which the curving-back 

 has been forced up a shght acclivity. I could find no indications 

 on the northern slope of Erendon Hill f of the movement under 

 notice ; and should this prove true with regard to all the northern 

 slopes of the Great Exmoor tableland, it will clearly point to a 

 wide- spread agency operating in a southerly direction, and affecting 

 only the summit-levels or southern declivities. At the same time 

 the possible discoveiy of local variations, or even reversions, in the 

 direction of curvature, would prove nothing further than a deflection 

 of the course of the moving agent. 



4. Transportation of BlocTcs. — The cause of the displacement of 

 slaty laminae on Brendon Hill (or a subsequently operating cause) 

 must have been capable of driving forward or carrying large blocks 

 of quartz to considerable distances from their native veins t. Many 

 of these were pointed out to me in the cuttings by Mr. Morgan 

 Morgans (Captain of the mines), not only near the surface but im- 

 bedded at depths of from three to five feet, in the more shattered 

 parts of the curved-back laminae. Overlying and intermixed with 

 the slaty debris and transported fragments, there is a considerable 

 thickness of reddish loam§. 



5. Ap-parent Reversal of Dip near Gupworthy. — In the neighbour- 

 hood of Gupworthy, about three miles from Ealeigh's Cross, a hori- 

 zontal adit was excavated some years ago, in search of copper. It 

 passes through a rich iron- " lode," which at the time was apparently 

 overlooked. This tunnel reveals a section of the uniform curving- 

 back of laminae on a very gigantic scale, the vertical extent of 

 curvature amounting to at least twenty feet. The direction of the 

 curvature, as elsewhere in this locality, is about south- south-east. 



* During these visits I had not the means of reiy accurately determining the 

 dip of the slaty cleavage or the precise direction of curving-back of the laminae 

 in different sections. 



t On the sides of the very steep railway-incline to the north of Ealeigh's 

 Cross, the edges of the slates in many places come within a few inches of the 

 surface, and exhibit no sign of disintegration. 



X These veins run along one side of the " lodes" of iron-ore, and often pre- 

 sent a considerable thickness. 



§ That the descent of matter by atmospheric action could never have given rise 

 to a great part of the angular detritus, with its loamy matrix, which forms so 

 general a covering of the earth's surface, was long ago clearly shown by Sir 

 Roderick I. Murchison. See chapter on Drift in ' Silurian System,' and more 

 especially a paper on the " Flint Drift " of the South-east of England, Quart. 

 Jour-n. Greol. Soc. vol. vii. p. 349. 



