KOCKS OP BOHEMIA. 593 



group is highly metamorphosed, the later one has been subjected to 

 but slight metamorphism, and that only in places; thirdly, the 

 strike is entirely different in the two groups, the beds of etage A 

 having a N.E. and S.W. strike; finally, this group contains 

 fragments of the preceding. 



The relations of etage A to the group above may be seen in 

 many sections, but notably in the neighbourhood of Pribram, as 

 shown in the following diagrammatic section from Jinec (Grinetz) to 

 Milin (fig. 1, p. 594). 



The beds of etage A have a strong lithological similarity 

 wherever exposed ; they consist of a series of green schists, grits, 

 ashes, and breccias, interstratified with variously coloured hornstones. 

 Massive beds of the^latter occur in this series, in the neighbour- 

 hood of Prague, at Sarka, and on the other side of the Moldau, near 

 Bohnice, also in the neighbourhood of Beroun, at Hudlice. 



Green ashy beds of this age with imperfect cleavage are seen 

 at Troya, Hudlice, Broum, Hlubos, &c. ; but, so far as I have seen, 

 they are unaccompanied by any contemporaneous flows. 



II. Camhrian Rocks (Sedgw.). 



Etage B, Barr. This is excellently exposed along the banks of 

 the Littava, between Jinec and Pribram, as shown in fig. 1. Kear 

 the village of Cenkau, the shales of etage C are underlain by coarse 

 grits composed of granitoid materials ; beneath these are finer 

 green grits succeeded in descending order by a series of interstra- 

 tified compact red shales, yellow grits, and finely laminated green 

 shales : these seem to be repeated by foldings. On reaching a mill 

 by the river-bank, south of Hlubos, the base of this series is seen 

 resting, as before mentioned, with a very marked unconformity, on 

 the last- described series (fig. 1). The lowest beds of the upper 

 series consist of coarse conglomerates, the pebbles of which increase 

 in size on approaching the base, where many of them exceed two 

 feet in diameter. The larger ones consist chiefly of hornstones, 

 identical in character with those of etage A ; of other pebbles there 

 are abundance of quartz, of a blackish schist, &c. The strike of 

 this group differs somewhat from that of the group below, and agrees 

 with that of the whole of the succeeding etages, viz. E.N.E. and 

 W.S.W. 



As an excellent description of the lithological characters of the 

 fossiliferous groups composing the basin is given by M. Barrande 

 (c/. Def. des Col. iv. p. 96 et seqq.), I shall merely give a short 

 outline of their nature. 



Etage C contains the well-known primordial fauna, and is exposed 

 on the northern side of the basin in the neighbourhood of Skrey, 

 and on the southern at and near Jinec (Ginetz). It does not 

 extend all round the basin, but is overlapped by the upper beds. 

 At Skrey it consists of very fine greyish or blackish shales ; at 

 Jinec of somewhat coarser and slightly gritty shales of an olive- 

 green colour, and often weathering into large concentric spheroids. 



Etage D is subdivided by M. Barrande into five "bandes," 

 Q, J. G. S. Ko. 144. 2 s 



