494 John Randall — Geology of Llnley Valley. 



either sucli as have been by common consent admitted to have been 

 at work in former times, or such as can be seen in operation at the 

 present day. 



Explanation or Sketch Map (PLATE XVII.) of Lough Derg. 



(119 feet). 



A 



Portumna. 



E 



Deepest sounding 



B 



Terrj'glass Bay. 



L 



Mountshannon. 



C 



Cloondavaun Bay. 



M 



Coolcoosaun. 



D 



Woodford. 



N 



ScarrifF. 



E 



Slieve Aughta. 







Scarriff Bay. 



F 



Drominagh Point. 



P 



Cornagnoe Valley. 



G 



Goose Bay. 



Q 



Slieve Bernagh. 



H 



lUaun More. 



R 



Einnaman Point. 



I 



Youghal Bay. 



S 



Slieve Arra. 



J 



Parker Point. 



T 



Killaloe. 



IV. — On the Noetherlt Extension of the Old Eed Sandstone 

 to linlet, and other geological features op the 

 Valley op Linlet Brook. 



By John Eanball, F.G.S. 



TWO remarkable geological features present themselves in this 

 little valley : one, the occurrence of the Upper Coal Measures of 

 Bewdley, together with the well-known Sjpirorhis Limestone ; the 

 other, that of the Bone-bed, succeeded by the no less interesting 

 Passage-beds, forming connecting links between the Old Eed Sand- 

 stone and Upper Ludlow Limestone. The order in which these occur, 

 taking both banks of the brook, appears to be this. 



1. Upon the surface, beds of drift, with boulders, of various 

 thickness. 



2. The Permians may be seen dipping rapidly away from the 

 younger Coal Measures, which crop out from beneath them, together 

 with the Spirorhis Limestone, which occurs between the two coals. 



3. Coarse sandstones, with " coal sheds," as the Shropshire sinkers 

 term them. 



4. Followed by Eed clays, about six feet. 



5. Light coloured grits, with plant remains, twenty feet. 



6. Hard micaceous, gritty and flaggy sandstones, with fish remains, 

 first discovered in collecting materials for my " Severn Valley," in 

 1860, and described as " The Upper Bone-bed " in a paper prepared 

 by the late George Eoberts, F.G.S., and myself, and read before the 

 Geological Society by Professor Eamsay, January 21st, 1863.^ 



The bed occurs on both sides the valley, and the spines, solid ribs, 

 and solid bones it yielded are stated by Sir Philip Egerton to be the 

 largest of the forms figured by him from the corresponding bed at 

 the Paper Mill, Ludlow. 



The sandstones of the "Upper Bone-bed," are altogether about 

 seven feet in thickness, but the Bone-bed itself is not more than two 

 inches ; and — 



7. Underneath it is a kind of flagstone, one foot nine inches thick, 

 with very interesting and distinct impressions of current or ripple 

 marks. 



1 See Quart. Journ. Geol. Soc., 1863, vol. xix. p. 229. 



