GREAT OOLITE. 3OI 



at Chalford, Bisley, and other localities ; they vary much in character in different 

 places. 



The Bath stone hardens and becomes whiter on exposure, after it has been 

 quarried. In its natural bed it is soft and moist, and it has been proved that a 

 cubic foot of the stone vi'ill absorb one gallon of water. The beds are largely 

 quarried, or mined, near Bath (on Odd Down, Combe Down, and Monkton Farley 

 Down), at Box, Corsham, Limpley Stoke, and Bradford-on-Avon. Stone was 

 formerly quarried on Bath Hampton Down. This stone is known as Combe 

 Down Stone, etc. Some of the beds, called Weather-stones (brown oolitic lime- 

 stones), are specially valuable for outside work, etc. ; the Scallet is of superior 

 quality for carving, being of very fine and uniform texture, but it is seldom worked. 

 Analysis of the stone shows about 95 per cent, of carbonate of lime.^ 



The action of the weather, by means of rain, frost, and carbonic acid, is very 

 obvious in these calcareous rocks. Thus not only are the beds broken up at the 

 surface into a rubble ; but the surfaces of the rocks are often pitted and eroded in 

 very fantastic hollows, with branching ridges, and crests.'- The Dagham Stone, 

 of Daglingworth Down, north of Cirencester, is a well-known example. 



The soil on the Great Oolite is a thin stone-brash. It is suited to the growth of 

 turnips and barley, but much wheat is also cultivated. 



The Great Oolite generally forms a well-marked feature in the neighboui-hood 

 of Bath, in Gloucestershire, and the borders of Oxfordshire ; but north of 

 Minchinhampton, the Inferior Oolite forms the main escarpment of the Cottes- 

 wold Hills. 



Stonesfield Slate. 



The Stonesfield Slate consists of fissile calcareous sandstones 

 or flags, which, splitting readily along the planes of bedding, pro- 

 duce the so-called 'slates' of Stonesfield, west of Woodstock, 

 in Oxfordshire. False-bedding is of frequent occurrence in the 

 beds. 



The formation is rich in fossil Plants, Molluscs, Insects, Fishes, 

 Reptiles, and Mammals. Corals, Echinoderms, and Crustacea are 

 also met with. The occurrence of Mammalia was first recognized 

 by Cuvier in 181 8, from a specimen obtained by Mr. W. J. 

 Broderip ; but for many years afterwards there was much con- 

 troversy concerning the mammalian characters of the fossil and 

 the antiquity of the deposit. 



The Mammals include the A??iphiiherium, Phascolotherium, and 

 Stenognathus. The Reptiles include Mcgalosaiirus Bucklandi, 

 Rhamphorhynchiis (a Pterosaurian), Teleosauriis, Tesiudo St?ickIa?iJi, 

 and the reptilian eggs Oolithcs sphixricus? The Fishes include 

 Pholidophorus, Lipidotus, Pycnodus, Ganodus, Hyhodus, Strophodiis, 

 Neinacanthiis, Ceratodus, etc. Among Crustacea, Pollicipes OoHticus 

 is the oldest known pedunculated Cirripede. Among the Insects 

 are a Dragon-fly, Lihellula, and a Butterfly, Palccojiiina. Among 

 the Mollusca are Rhynchoftella concinna, Trigonia impressa, Gervillia 

 acuta, Pholadomya actiticosta, Os/rea gregaria, Ammonites gracilis, 

 Bclcmnites fusiformis, B. hessinus, etc. The Plant-remains include 



^ See Mem. Geol. Survey, vol. ii. part 2, p. 

 ^ Phillips, Geol. Oxford, etc. p. 143. 

 ^ W. Carruthers, Q. J. xxvii. 447. 



