The fissility of the rock is developed by exposure to frost. Easton, Dene and Kirkby are important localities. The Collyweston slates are arenaceous limestones which have been used for roofing slates since the time of Henry VII. In Rutlandshire, Northamptonshire and Lincolnshire the following beds, in descending order, belong to the Inferior Oolite: Lincolnshire limestone (shelly, coral-bearing and oolitic), Collyweston slate, Lower Estuarine series and Northampton Sands (hard calcareous sandstones, blue and greenish ironstones and sandy limestones). Near Chipping Norton in Oxfordshire the " Chipping Norton Limestone " lies at the top of a very variable series of rocks. Between Andoversford and Bourton-in-the-Water the Inferior Oolite is represented by ragstones (Ferruginous beds, Clypeus Grit, Trigonia bed, Notgrove Freestone, Gryphite Grit) and freestones (Upper Freestones and Harford Sands, Oolite Marl, Lower Freestone). The " grits " are really coarse-grained limestones or calciferous sandstones. The ragstones are fossiliferous, earthy and iron-stained oolitic limestones. The freestones are compact oolite limestones. The Pea Grit series contains pisolitic limestone and coarse, iron-stained oolite and sandy limestone. of Dursley contains the following subdivisions: - The basal sandy series, which is closely related with the underlying Lias, is usually described as the Midford Sands (from Midford, near Bath), but it is also known locally as the Bradford, Yeovil or Cotteswold Sands. In the Cotteswold Hills it is a series of marine deposits, 264 ft. It is an extremely variable assemblage of strata. The Inferior Oolite, called by William Smith the " Under Oolite " from its occurrence beneath the Great or " Upper Oolite " in the neighbourhood of Bath, received its present name from J. The Great Oolite and Inferior Oolite are treated here. The oolites are usually divided into: the Upper or Portland Oolite, comprising the Purbeck, Portland and Kimeridge stages the Middle or Oxford Oolite, including the Corallian, Oxfordian and Kellaways beds and the Lower Oolites, with the Cornbrash, Great or Bath Oolite (Bathonian), Fullonian and the Inferior Oolite (Bajocian). Custom still sanctions its use in England, but it has been objected that the Oolitic (Jurassic) system contains many strata that are not oolitic and since oolitic structure occurs in limestones of all ages, it is misleading to employ the word in this way. Buckland and others, it was gradually introduced for the calcareous rocks of the British Jurassic until it came to comprehend the whole system above the Lias. Brochant de Villiers in 1803, and through the labours of W. The term appears to have been first applied in this latter sense by A. In stratigraphical geology, the oolite is a division of the Jurassic system (q.v.). In petrology it denotes a type of rock structure characterized by the presence of minute spherical grains resembling the roe of a fish if the grains become larger, the structure is said to be pisolitic (Gr. c36v, egg, ALOo, stone), in geology, a term having two distinct meanings.
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