34- LOWER OOLITIC ROCKS OF ENGLAND: 
beds are overlaid by fissile sandy strata known as the Collyweston 
Slate, and by compact shelly and oolitic limestones, known collec- 
tively as the Lincolnshire Limestone. The upper limit of the 
Inferior Oolite Series is over a great part of the area well-marked, 
the beds being overlaid by the Upper Estuarine Series, which is 
the local base of the Great Oolite Series. 
Thus the Inferior Oolite, in its course through England, exhibits 
almost every variety of stratified rock. In some places, as on the 
Cotteswolds, we have fine false-bedded oolites furnishing excellent 
freestone ; also beds of soft oolite-marl ; and layers of coarse 
oolite and pisolite. In other places, as near Bridport, the oolite 
becomes very ferruginous, and almost an oolitic iron-ore. Again, 
near Lincoln, we find beds of compact limestone, with scattered 
oolitic grains, and beds of shell-limestone. Conglomeratic beds 
are met with on the eastern borders of the Mendip Hills, and 
tiny quartz pebbles occur in some beds in the Cotteswold Hills. 
Distinct beds of sand, and even of clay, are intercalated in 
places on the northern Cottes\volds ; and near Chipping Norton 
most of the strata are more or less sandy in character. 
The surface-beds generally present a rubbly appearance, while 
some of the beds not exposed to atmospheric influences are blue in 
colour. False-bedding is, as a rule, conspicuously developed in 
the oolitic freestones. 
Where best developed, as near Cheltenham, the beds attain a 
thickness of upwards of 250 feet, while near Bridport the full 
thickness is no more than 15 feet. (See Fig. 31, p. 53.) From 
the Cotteswold area there is evidence of attenuation as we proceed 
towards the neighbourhood of Oxford.* This is caused by tho 
overlap of higher across lower members of the formation. 
Beds bored by Annelides or other marine organisms occur at 
various horizons in the Inferior Oolite ; and beds with rolled 
fragments of oolite are alao met with at different stages. These 
phenomena mark a certain amount of local unconformity or con- 
temporaneous erosion, as the case may be ; but they cannot be 
taken in any case to indicate a great lapse of time, for they occur 
at different levels in the same palaeontological division. There 
are also occasional perforations in the limestones like those 
characterizing the " Dagham Stone " of the Great Oolite 
(see p. 286). 
The Inferior Oolite sometimes rests directly on the Lias, 
without the intervention of the Midford Sand, as near Radstock ; 
while in other places bordering the Mendip Hills it rests on the 
Coal-measures and on the Carboniferous Limestone. In no other 
tract, however, have we any actual evidence of marginal accu- 
mulations ; although some of the more sandy beds with plant- 
remains in Oxfordshire, the layers with rootlets in the North- 
ampton Sand, and the estuarine beds in the midland counties, 
betoken the proximity of land. 
* See Hull, Geology of Cheltenham ; W. C. Lucy, Proc. Cotteswold Cub, vol. v. 
p. 8.; Topley, Quart. Journ. Geol. feoc., vol. xxx. p. 186; and Buckman, Ibid., 
Tol. xlv. p. 468. 
