580 Geological Society. 



together in a limestone-matrix. In the sections big blocks may be 

 seen in process of division by shearing-movements, which have 

 succeeded the folding. The limestone seems generally to have played 

 the part of a plastic body, and has accommodated itself as a matrix to 

 the folded and isolated fragments of epidiorite, between which it has 

 been squeezed. Thus the origin of the conglomerate is satisfactorily 

 proved by the fact that it contains fragments of rocks newer than 

 the sediments in which the crush-conglomerates are embedded. The 

 author considers that it would be safer to regard such conglomerates 

 in this area as have a calcareous matrix as having been formed by 

 crushing. 



June 5th.— J. J. H. Teall, Esq., M.A., V.P.R.S., President, 

 in the Chair. 

 The following communications were read : — 



1. ' On the Passage of a Seam of Coal into a Seam of Dolomite.' 

 By Aubrey Strahan, Esq., M.A., E.G.S. 



The author was informed by Mr. N. R. Griffith in 1900 that the 

 Seven-Eeet Seam of the Wirral Colliery had been found to pass into 

 stone of an unusual character. Eor a distance of 1600 yards from 

 the shaft this seam was good, and about 4 feet thick. A little farther 

 in, bands of stone from 1 to 10 inches thick made their appearance 

 in it, and, gradually increasing in thickness, these bands eventually 

 constituted the whole seam, the last traces of workable coal dis- 

 appearing at 250 yards from the point where the change first began. 

 The boundary of the barren area has been found for a distance of 

 1480 yards, and it runs north and south. The stone is at first black, 

 but after weathering it becomes grey, and displays curious structures, 

 among which are pisolitic, or mammillated structures, the inter- 

 vening spaces being filled with coaly matter. One specimen displays 

 woody tissue filled with dolomite. Analyses by Dr. W. Pollard yield 

 from 18'5 to 13 per cent, of magnesia. The phenomena are not 

 those of a • wash-out,' as there is no sign of erosion, but there is 

 proof that the dolomite was formed in almost motionless water, and 

 the conditions appear to have been those under which a tufa would 

 form. It appears to have been formed on a spot to which clastic 

 material scarcely gained access, and which was reached even by 

 vegetable matter in scant quantity and in a finely divided condition. 



2. ' On some Landslips in Boulder-Clay near Scarborough.' By 

 Horace W. Monckton, Esq., E.L.S., V.P.G.S. 



In 1893 Mr. Clement Reid drew attention to a foliated structure 

 developed in Drift at Beeston, near Cromer (Proc. Geol. Assoc, vol. xiii, 

 p. 66), and soon afterwards the present author noticed examples of 

 a very similar character in Boulder-Clay on the Yorkshire coast. 

 The Clay forms much of the cliffs, and slips, large and small, are very 

 frequent. When the Clay is dry, vertical cracks forming a sort of 

 columnar structure occur, and the Clay breaks away in lumps, while 

 a moister condition causes flow, producing more or less horizontal 

 flow-structure which, as in the Cromer case, has the appearance of 

 irregular bedding. The author illustrated his remarks by photo- 

 graphs of the cliffs taken by himself. 



