Vol. 68.] CAEBOXirEKODS LIMESTOJNE AT UPPEE VOBSXER. 73 



EXPLANATION OF PLATES II-Y. 



Plate II. 



Geological map of the L^pper Vobster Inlier, on the scale of 12 inches to 

 the mile, or 1 :5280 ; and horizontal section along the line ABC oq 

 the map, on the scale of 1 : 2500. [The map is oriented north and 

 south.] 



Plate III. 



Fig. 1. Vobster Quarry: western end, south side, August 1911. Highest 

 Seminula Beds — inverted and sharply folded in the corner of the 

 quarry on the observer's right ; vertical in the bluff on the leit. 

 a to b on the map (PL II). (See p. 64.) 

 2. Yobster Quarry : Avestern end, August 1911. Highest Seminula Beds, 

 overfolded ; h to c on the map (Pi. II), The white, weathered rock- 

 surfaces on the brink of the quarry, on the observer's left, yielded 

 fossils characteristic of the summit of the Seminula Zone. (See 

 pp. 63, 64.) 



Plate IY. 



Fig. 1. Yobster Quarry: eastern part of the northern face, August 1911; 

 d to cV on the map (PI. II). Inverted Seminula Beds, capped by Lias. 

 Bedding in the Carboniferous Limestone obscured by calcite-masses 

 and slickensides, at the eastern end of the section. (See pp. 62-63.) 

 2. Yobster Old Quarrj^ : face of the quarry west of tlie tramway-tunnel ; 

 ftog on the map (PI. II). Beds of the Grrit-&-Shale Mass in faulted 

 superposition upon limestones (Dj) of the Southern Limestone Mass. 

 (See p. 67.) 



Plate Y. 



Yobster Old Quarry : general view, looking westwards. For explanation and 

 description of the sections, see text-figure, p. 68, and pp. 67-70. 



Discussion. 



Mr. G. Baeeow congratulated the Author on his paper, and drew 

 attention to its important bearing on the increase in intensity of 

 post-Carboniferous earth-creeps, or overthrusts, as one proceeds 

 southwards. In the North of England these are but feebly, if at 

 all, represented. In N'orth Staffordshire the Coal Measures are 

 locally thrown on end, and occasionally broken up by such nioTe- 

 ments. In the South-West of England they are no longer local, 

 they are regional : and the Author's work deals with an area 

 between the two. The speaker said that he would welcome further 

 evidence of the age of the sandstones or grits that were shown in 

 the diagram, projecting into, or breaking through, the limestone. 



Mr. W. A. E. UssHEE said that he had published an explanation of 

 the phenomena by overthrust-faulting in a paper on 'Coal Prospects 

 South of the Mendips,' conamunicated twenty years ago [1891] to 

 the Somerset Archa3ological & Natural History Society. The 

 illustration showed the shifting of the crest of a normal anti- 

 cline. Mr. McMurtrie's work, however, especially a paper com- 

 municated to the Institution of Mining Engineers in 1901, showed 

 the prevalence of reversed dips in the Coal Measures (about 

 Luckington and Yobster), justifying the view sketched on the 



