162 



REPORT — 1869. 



forms peculiarizing the reefs are positively aggregated in an upper and lower 

 mass at Crickley on the Inferior Oolitic beds. 



Dr. Wright noticed some years since* an Oolitic coral-reef near Frith 

 Quarry, on the northern sjiur of Brown's Hill, about two miles from Stroud. 

 There is a corresponding reef on the ojjposite side of the valley, the whole of 

 the intervening space having been excavated by denudation. The coral-bed 

 consists of large masses of coralline limestone imbedded in a fine-grained 

 cream-coloured mudstone. The corals are in a highly crystalline state, so that 

 the genera and species are determined with difficulty. The bed is from 1.5 to 

 20 feet in thickness, and forms one of the finest examples of fossil coral-reefs 

 that Dr. Wright is acquainted with in the district. The bed may be traced 

 along the escarpment, in a north-westerly direction, for several miles, to 

 Witcomb and Crickley on the west, and to near Cubberley and Cowley on 

 the east, where it was worked several years ago. Judging from the thick- 

 ness of the bed, and the abundance of corals it contains, it must have formed 

 a barrier reef of considerable magnitude in the Jurassic sea. The following 

 is a section showing the relative position of the Lower Coral-reef. 



Section of the Lower Coral-reef, in the Inferior Oolite, at the Quarry, North 

 Frith Wood, near Broivn''s Bill, Gloucestershire. 



Lithological Characters 

 and Tliickness. 



Cream-coloured Marl, with 

 several inconstant layers 

 of Mudstone, upper part 

 passing into a loose, fri- 

 able Fi-eestone, with large 

 Terebratuta fimbria. 

 From 20 to 25 feet. 



Fine-grained Oolitic Lime- 

 stone, very white, and 

 emitting a metallic ring 

 when struck with a 

 hammer. 

 40 to 50 feet. 



Coarse brown ferruginous 

 OoUte. 



Masses of Coralline Lime- 

 stone, imbedded in a 

 light-coloured Mudstone ; 

 the Corals highly crystal- 

 line, forming the chief 

 Jiart of Ihe bed. 

 15 to 25 feet. 



Brown ferruginous Pisohtio 

 rock. Pea-grit structure 

 not much exposed. 



Beds, 



Upper Freestones. 



Oolite, M.\rl. 

 Middle Coral-bed, 



Freestones. 



Lower Ragstoxes. 



Lower Coral-reef. 



Pea-grit. 



Organic Remains. 

 Leading Fossils, 



Thamnasirrea, Isastnca, 

 Axosmilia, Terebratula 

 fimbria^ T. carinafa^ T. 

 maxiliata^ Hhyn, Lycetti. 

 Lucina fj'righfi, Lima 

 pontonis. 



Shelly fragments, not 

 determinable. 



Terebratuta plicata. 



Latimceaiidra, Thamtms- 

 frcBUj Jftaelrtpa, Axostni- 

 Ua, Thecoemilia, Pecfen 

 Deicalquei, TricJiifes, Lu- 

 cina Wrighfi. 



Jjima sidcafay Hinnites 

 nhjeciui, Ceromya Bajoei- 

 amt, Acieula cnmplicafa. 

 Nerita cosfafa,Trocftofoma 

 carinafa, Pyqaster, Hybo- 

 clypits, Diadema. 



* Dr. Wright lias kindly sent me these details, 

 M.D., F.G,S., Cotteswold Club. 



See " On Coral-Eeefs," by T, Wright, 



