PEECARBONirEEOUS EOCKS OP CHAEITWOOD FOEEST. 339 



the green rock shows the usual constituents, with some signs of 

 decomposition, a larger proportion of viridite, including some chlorite. 

 The materials are probably waterworn. 



There is rock in the spinney by the New-Cliff quarry which is 

 externally different from most of the Blackbrook series. It has, 

 however, something in common with the Ives-Head beds. This is 

 a coarse greenish-grey grit, of well-rounded grains. Microscopically, 

 even this has a general resemblance to the specimen from Moorley 

 Hill, except that the greater part of the green mineral is doubly 

 refracting. In both, the felspars with their included microliths 

 and general structure recall those in many modern trachytes. 



(2) Additional Correlations. 



On the west side of the anticHnal the Blackbrook series appears 

 everywhere to be overlain by the coarse ashes of the Monastery, 

 Hanging Stones, &c., the agglomerates of the High-Towers region, 

 and the rocks of Sharpley. If, then, we are right in supposing 

 that the lowest beds on either side of the anticlinal belong approxi- 

 mately to the same series (and the throw of the strike-faults is 

 much less than was formerly supposed), the equivalents of the 

 coarse agglomeratic rocks of the western side ought to be found 

 above the beds already described on the eastern. Bearing in mind 

 the possibilities of change in aspect, we minutely reexamined all 

 the latter district, with the following result: — The soft ashes and 

 pale green flinty slate of Whittle Hill have obvious affinities with 

 the Blackbrook type. But in a spinney due north of the quarry, 

 at no great distance, we found rock clearly in situ, not only of an 

 entirely different type, but so closely i-esembling the Monastery 

 coarse-ash beds, that without the labels our hand-specimens could 

 not be distinguished from some of them. The microscopical evi- 

 dence agrees with this. There are the usual constituents, a good 

 deal decomposed, with much hornblende giving a more or less schistose 

 structure, and but little quartz. The rock-fragments much resemble 

 devitrified rhyolites; and in parts of the shde the fragmental 

 structure becomes almost obliterated, while in others it is very 

 distinct. 



Por this correlation there is additional evidence. Above the 

 coarse ashes of the Monastery and Hanging Stones are vast piles of 

 agglomerates. Here, on the eastern side, no such agglomerates 

 occur, so far at least as we know ; but we do find at more than 

 one point beds of a dark-green grit, which have no small resem- 

 blance to the matrix of some of the agglomeratic beds. Also a thick 

 grit bed on the Buck Hills * has much likeness to a bed on the 

 High-Towers ridge ; and though most of the beds hereabouts are 

 banded slates which have no obvious equivalents across the anti- 

 clinal, yet it may be noticed that there are indications of stratified 



* The coarser rock of the Buck Hills contains a considerable amount of 

 quartz ; and the microscope shows many lapilli, one or two exhibiting acicuLu* 

 microliths of felspar, as weU as included crystals of the same mineral. 



2a2 



