240 ME. C. T. TEECHMANN ON THE LITHOLOaY [June 1914, 



Ryhope Asylum Quarry. — XXIX. ' Gasteropod-reef.' A 

 friable rock, occurring in flaggy masses over a limited area. The 

 uncompacted portions exhibit crowded masses of fossils, including 

 gasteropods, Chiton plates, Nautilus, valves of Balcevellia, Area, 

 remains of bryozoa, etc. All the organisms are encrusted with a 

 fine coating of dolomite. 



XXX. Underlying the above. A hard, white, highly-compact 

 and crystalline rock, occurring in large irregular masses. Fossils 

 are to a great extent obscured, but large Fenestellids are seen. 



Insoluble residue 



XXIX. 



0-22 



XXX. 



0-47 



Fe o 3 , etc 



0-44 



0-37 



CaC0 3 



MgCO, 



SO, 



55-14 



44-69 



0-09 



55-37 



44-43 

 tr. 









Totals 



100-58 

 1-93 



100-64 



Calcite 



3-68 



Dolomite 



97-90 



95-12 



Easington Colliery. — A quarry on the eastern slope of the 

 reef. The Shell- Limestone has here undergone considerable segre- 

 gation, and a small development of cellular rock is seen. 



XXXI. Normal unaltered Shell- Limestone. A rather friable 

 white rock, almost entirely made up of bryozoa, small Strophalosia y 

 and other reef-organisms. 



A stained section indicates that the organisms, especially the 

 bryozoa, are very highly dolomitized, and show a cryptocrystalline 

 structure. The matrix is chiefly dolomite, highly contaminated 

 with dirt-inclusions, but also shows a good deal of calcite 

 arranged along definite lines. In the material filling the cells of 

 the bryozoa clear crystals of both dolomite and calcite are seen. 

 (See PL XXXVI, fig. 3.) 



XXXII. Adjoining the above, and passing imperceptibly into it. 

 Hard, coarsely - crystalline, irregularly - segregated, white rock. 

 Fossils are almost entirely obliterated ; but, on careful examination,, 

 traces of Fenestellids can be detected. 



XXXIII. Occupying spaces in, and closely associated with the 

 above. A soft, brownish, incoherent material, crumbling when dry 

 to a fine powder. About 99 per cent, of this passes a sieve of 240 

 meshes per linear inch. 



XXXIV. Residue obtained on riddling the above. 



XXXV. Powder similar to XXXIII, but yellow in colour, from 

 another part of the quarry. 



XXXVI. Residue obtained on riddling the above. 



