482 LOWER OOLITIC ROCKS OF ENGLAND : 
The Inferior Oolite in Dorsetshire, Somersetshire, and the Cotteswolds ; 
the Fuller's Earth Eock of Dorsetshire ; the Chipping Norton Limestone 
in Oxfordshire ; the Lincolnshire Limestone ; and the Great Oolite, are 
locally employed. 
The " White bed " in the Northampton Sand of Harleston near North- 
ampton/.has been used for road-mending and for foot-paths. 
Some of the harder beds in the white limestone of the Great Oolite 
(Dagham Stone) are used near Cirencester ; also the Great Oolite Lime- 
stone in Northamptonshire and Lincolnshire. 
Of the local material the Forest Marble is usually preferred : the 
hard shelly limestones being employed along the outcrop from Dorset- 
shire to Oxfordshire, and locally at Lillingston Lovell in Bucking- 
hamshire. Belonging to the same division, the hard calcareous sand- 
stones of Charterhouse Hinton, near Bath, are also employed. 
The Cornbrash is also largely used for road-metal, material being 
obtained from most of the quarries. 
Limestone is in places quarried for use as a flux in the Iron-furnaces ; 
in smelting ores, which, containing a good deal of earthy impurity (silica 
and alumina), are not readily fusible. 
The Lincolnshire Limestone of Glendon is thus employed; the Great 
Oolite of Bradford-on-Avon was formerly sent to the Westbury Iron- 
works; and the Great Oolite of Thrapston is locally used. 
Stone-tiles or " Slates" 
The calcareous " slates " of the Jurassic system are strictly 
speaking flagstones or tilestones. The more important of them 
are fissile calcareous sandstones or sandy limestones, more or less 
oolitic and micaceous. Organic remains are sometimes abundantly 
distributed over the surfaces of the rock, and Dr. Sorby has 
remarked that " the fissility of the Stonesfield Slate is, in great 
measure, clue to minute laminae derived from Ostrea and 
Brachiopoda."* The rock splits according to the plane of depo- 
sition, hence the slates vary in thickness and are not uniform 
individually : but they are found serviceable for roofing-purposes. 
Other stone-slates consist of thin layers of shelly and oolitic 
limestone that occur interstratified with shaly clays, as in the 
Forest Marble. 
Stone tiles have been in use since Roman times, and they have 
been obtained from the Inferior Oolite, including the North- 
ampton Sand and Colly weston Slate; as well as from the 
Great Oolite Series, including the Stonesfield Slate and Forest 
Marble. 
Referring to the roofing-tiles obtained from the Forest Marble of 
Chavenage, near Tetbury, Lycett remraks that the weight of these flags is 
fully three times that of ordinary slate ; "the tile, however, possesses 
much advantage in point of comfort compared with slate, as it is a much 
worse conductor of heat, the upper parts of houses covered with the 
stone tiles are much less exposed to the vicissitudes of the external 
tempera ture."f 
Northampton Sand. 
Thin fissile calcareous sandstones have yielded material that has been 
used for roofing-purposes, under the name of Duston Slates. (Seep. 182.) 
* Quart. Journ. Geol. Soc., vol. xxxv. p. 83 (Proc.)- 
f Cotteswold Hills, p. IOC. 
