298 PEOr. T. G. BONNEY AND MISS C. A. EAISIN ON [Maj^ iSqQ^ 



consists mainly, beneath the schist,^ of a dark green soft chlorite- 

 rock. This forms several ellipsoidal masses 10 to 15 feet long, 

 resembling the bolster-like spheroids of a diabase. Between these 

 are irregular whitish masses or bands of a rock (closely laminated and 

 much corrugated, sometimes even fibrous), consisting mainly of 

 colourless actinolite. On the western side of the quarry, we find 

 in the upper part similar chlorite-rock interrupted by green schist 

 and by two actinolitic masses, and then, after a few feet covered 

 by brambles, more rock, which is in places distinctly actinolitic. 

 This craglet terminates at the pool. 



The chlorite-schist rises as a roughly triangular boss towards 

 the eastern side of the quarry.^ The talc-schist is still to be 

 found in the north-western corner (and at the north-east) clinging 

 to the chlorite-rock, but for the most part has been completely 

 removed along the band B in the figure to which we have referred, 

 and then is found on the eastern face. On this side of the quarry 

 it extends above and beyond the uprising chlorite-schist already 

 mentioned for about 20 yards, and then, towards the low flat 

 ground, small outcrops of green schist or schistose rock occur. 

 These are crushed almost out of recognition (sometimes with weU- 

 marked strain-slip cleavage), but suggest the possibility that 

 chlorite-schist, serpentine, and even the gabbro or green schist are 

 all represented. 



Thus the chlorite-schist rises in the northern and the western face- 

 to a height of about 15 feet, projects in the low triangular boss on the 

 east, and is found at the foot of that slope ; while west of the quarry, 

 judging from one small boss, it may extend through the green 

 schist. It may have intruded into the gabbro, into the original of 

 the talc-schist, and into that of the crushed actinolitic rock. This- 

 last-named might possibly be derived from a pyroxenic rock, perhaps 

 the diallage-rock. 



All the rocks in the above-described section have evidently been 

 much disturbed. Even the abrupt rise of the little plateau from 

 the lowland, with the formation at its edge of pools and springs of 

 water, suggests possible lines of fault.^ The dip of the schist is 

 generally northerly, but with variations. The actinolitic rock 

 (north and west of the quarry) is crumpled into small zigzags, 

 while the fibrous actinolite itself is probably an evidence of the 

 effects of pressure.* Of the pressure-modification shown in the fiaky 

 chlorite-rock we have already spoken. The talc-schist on the eastern 

 side has, first, planes which dip westward about 44°, next curving 

 planes dipping northward 70° or more ; farther on, other planes cross 

 these at acute angles, in such wise that the rock is crushed into small 

 rhomboids or ellipsoids as if by an attempt at strain-slip cleavage. 

 This part seems to include 'eyes,' similar in shape and relations 

 to those which occur uncrushed in masses of squeezed serpentine. 



^ 'A' of the original figure. Quart Journ, Geol. See. vol. xxxvii (1881) p. 44. 

 2 Marked ' X ' in fig. Ji, ibid. p. 44. 



^ Compare Malldraeth Marsh for an example on a much larger scale. 

 * T. G-. Bonney, Quart. Journ. Geol. See. vol. xlix (1893) pp. 101, 102. 



