620 Geological Society. 



the Snaefell Laminated Slate, and the Agneash Grit 

 follow in descending order, dipping north-westward. The last- 

 named is markedly laminated. The ascending series, by dip, is 

 again repeated after a fault, and at Tholt-y-will the Schistose 

 Breccia appears near or at the top. The best sections of the 

 latter for stratigraphy are in Glen Anldyn and Sulby Glen. The 

 Schistose Breccia is therefore taken as an additional upper member 

 of the series. 



General Distribution of the Manx Slates. — The Agneash 

 Grit in Maughold Head is nearly vertical, and is followed by the 

 Snaefell Laminated Slates. The height to which the Barrule Slates 

 attain diminishes from east to west. The Schistose Breccia depends 

 on the presence of those slates ; its occurrence is noted in four 

 areas to the west of the Barrule Slates, which are repeated by 

 faults. 



The Position of the Lonan and Niarbyl Flags is 

 indicated by two colours on the map. The Lonan Flags, etc. are 

 never seen underlying the Manx Slates, but they overlie the 

 earlier Manx Slates in the lower country near Maughold, near 

 Sulby Glen, and north of Peel. They may, therefore, be called 

 the Sulby-Glen Series. 



Characters and Origin of the Schistose Breccia. — 

 Prof. C. B. Van Hise gives three criteria for autoclastic rocks, with 

 none of which do the Schistose Breccias agree, namely, the fragments 

 of an autoclastic rock must be derived from the adjacent material; 

 whether they be below or above ; and the rock itself may be traced 

 into an ordinary brecciated rock. The fragments examined do 

 not agree with this statement, The rocks are not truly con- 

 glomeratic — some are too soft, or others too hard. 



Examples at Ballaneary and elsewhere occur, of true autoclastic 

 rocks, showing contrast. 



2. ' On the Wash-outs in the Middle Coal-Measures of South 

 Yorkshire.' By Francis Edward Middleton, F.G.S. 



In the neighbourhood of Aldwarke and Thrybergh extensive 

 workings have proved that wash-outs have occurred at various 

 horizons in the Middle and Lower Coal-Measures, and the limits 

 of certain of these have been accurately laid down on plans. 



Denudation in the Barnsley Seam has been found over an area 

 1700 yards in length from east to west, and in the Parkgatc Seam 

 (240 yards below) over an area 2600 yards long from north to 

 south. In neither case was the wash-out completely crossed, but 

 its width cannot be less than 600 yards. The Swallow-Wood Seam, 

 lying 60 yards below the Barnsley and above the Parkgate Seam, 

 has been partly worked under the same area ; but no signs of a 

 wash-out have been found. 



The opinion of the author is that the wash-outs occupy the sites 

 of winding streams, meandering through the alluvial tracts in which 

 the coal-seams were being formed. 



