TRANSACTIONS OF SECTION C. 611 



in the rocks of Peldar Tor, Sharpley, Szc, and one such grain is attached to a 

 fragment of minutely devitrified rock. Hence, as shown by larger fragments, the 

 ■Charnwood series has contributed to the materials of this conglomerate, but the 

 more abundant appear to have been derived from volcanic vents, the locality of 

 which is at present undiscovered.^ 



Trias. — The Bunter beds and the lower part of the Keuper consist of more or 

 Tess coarse materials, while in the remainder of the latter such deposits are rare and 

 local. Hence it is e-vident that after the deposition of the Keuper sandstones a 

 very different set of physical conditions prevailed. The lower series consists of 

 sandstones and conglomerates; these beds occur in considerable force on the 

 eastern side of the Pennine chain, have a great development in Lancashire and 

 Cheshire, and thin away towards the south-east, almost disappearing in eastern 

 Leicestershire and in Warwickshire. As the Trias is followed southwards, along the 

 valley of the Severn, the Bunter in like way dies out, while the Keuper marls may 

 be traced on into Somersetshire and Devon. In that region also there is a grand 

 development of the lower and coarser members. As might be expected, there are 

 considerable differences between the lower Triassic deposits of the northern and 

 southern areas, so that it will be convenient to speak of them separately. The 

 northern group, as is well known, is separable in the Midland and north-western 

 district into the Lower Bunter sandstone, the Pebble-beds, and the Upper Bunter 

 sandstone, over which come, more or less imconformably, the Keuper sandstones. 

 Pebbles are either absent from, or very rare in every part of the Bunter except the 

 pebble-bed, and are generally small and scarce in the Keuper sandstones, except 

 in the basement breccias. It will be convenient to make a few remarks on them 

 before dealing with the associated sands and sandstones. The pebbles in the 

 Bunter conglomerate are most abundant, and generally attain the largest size in the 

 Midland district. Towards the north-west, though the conglomerate attains a 

 thickness of more than 500 feet, pebbles are rarer and smaller, and this, I believe, is 

 also the case in Yorkshire, though the thickness of the deposit is not so great. I 

 • can, however, answer for the occurrence of pebbles of fair size and in considerable 

 abundance for some distance to the north of Retford. In the Midland district 

 they are very frequently from about 2" to 4" in diameter, though smaller are inter- 

 mingled and occasionally some of larger size ; these attain in certain localities to 

 a diameter of 6", or even more. The majority, so far as I know, are well 

 rounded. In this district many different kinds of rock are found in the con- 

 glomerate; the most abundant are quartzose — vein-quartz, quartzites and hard 

 grits or sandstones. Besides these we find chert and limestone from the Car- 

 boniferous series, various fossiliferous rocks of Silurian, Ordovician, and possibly 

 Cambrian age, with mudstones and argillites, more or less flinty, of uncertain 

 date. Felstones, using the term in a wide sense, are not rare, and granites or 

 granitoid rocks sometimes occur. These, however, together with the scarce frag- 

 ments of gneiss and schist, are usually very decomposed. A hard quartz-felspar 

 grit, sometimes very like a binary granite, may be foimd, and I have noticed a 

 peculiar black quartzose rock of rather schistose structure. As the lithology of the 

 Bunter conglomerate has already attracted the notice of more than one author, I 

 shall restrict myself to a brief mention of its more salient features. The most 

 abundant rock is a quartzite, frequently so compact as to give a rather lustrous 

 sub-conchoidal fracture, in which the individual grains can be with difficulty 

 distinguished. In colour it varies mostly from white to some tint of grey, but is 

 occasionally 'liver-coloured.' Rather obscurely marked annelid-tubes are the 

 only organic indications which I have observed in these quartzites, and these are 

 very rare. Under the microscope the rock consists chiefly of quartz fragments, 

 of various forms in different specimens, with an occasional fragment of felspar 

 (sometimes, I think, silicified), a flake of white mica, a grain of tourmaline, and of 

 ■an impure epidote (?). As a rule it is easy to distinguish this quartzite from the 



' I pass by tlie interesting pebbles of hematite, which have received special 

 -attention from Mr. Gresley. 



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