Vol. 68.] CAEBOXIFEROTJS LIMESTONE AT TTPPEK YOBSTEK. 71 



north-western angle of the cross-roads, the rocks are not only much 

 overgrown, but also, since the quarry is full of water, largely 

 inaccessible. Xo fossils, other than crinoid-fragments, were seen 

 in the beds of grey limestone examined on the northern side of this 

 quarry. 



The easternmost exposure of the Carboniferous Limestone is 

 found in another long-disused quarry, adjacent to the buildings 

 named Bilboa. Here, quarrying has exposed the strata beneath a 

 thin covering of Lias. As in Yobster Quarry, the Lias rests upon 

 a level-planed surface of Carboniferous Limestone. Since the 

 quarry is filled with water and its sides are precipitous, close 

 examination of the Carboniferous Limestone is impossible. Ko 

 determinable fossils were seen in the few beds accessible at the 

 southern end of the quarry. The dip of the beds appeared to be in 

 a direction west of north. 



(c) The Grit-&-Shale Mass. 



As jegards this mass, there is little to add to the description of 

 the beds given by Mr. AYinwood. Reference should be made to 

 the admirable section which illustrates his second paper on Yobster.^ 

 The complete tunnel-section is given there ; and I find that the 

 succession of beds traversed from south to north between the two 

 masses of Carboniferous Limestone was as follows (the appended 

 section, PI. II, follows this line) : — (1) Shales, about 15 feet " ; 

 (2) MiUstone Grit, about 41 feet ; (3) Shales, about 50 feet. 



The beds of (1) and (2) are inclined southwards at a high angle ; 

 those of (3) appear to be folded anticliually, dipping southwards 

 in the middle portion of the tunnel, and northwards in the northern 

 X^art. 



Beds representing portions of (1) and (2) are seen in the face 

 of Yobster Old Quarry to the west of the tunnel, and have been 

 described above (p. 67). It is there found that the shales (1) 

 include shales and fine-grained sandstones, and that the Millstone 

 Grit (2) is formed of quartzites. 



The tunnel is now bricked up almost from end to end, but small 

 portions of the section can still be seen in three archways within 

 the extent of the brickwork, the positions of which are shown in 

 Mr. Winwood's section. In the southernmost of these three arch- 

 ways, quartzites belonging to (2) are exposed. In the two northern 

 archways portions of the shale-series (3) are seen ; and it is found 

 that fine-grained greenish sandstones are here intercalated with 

 shales. In addition, there is a very small exposure of the contact 

 between the shales (3) and the Carboniferous Limestone of the 

 Northern Mass. This occurs within the tunnel, just at the northern 

 end of the brickwork. Here a very thin seam of coal and a thin 

 band of red sandstone intervene between the black shale of (3) and 



1 Winwood, 1893, folding plate. 



- The figures stated here represent vertical thickness. 



