INFERIOR OOLITE. 29I 



All these subdivisions of 5 and 6 have been collectively grouped by Dr. 

 Lycett as the Spinosa stage, characterized by Rhyuchonella spinosa. No. 3 has 

 been termed the Fimbria stage, being characterized by Tcrcbratnla funbyia ; it con- 

 tains also Rhynchondla siibobsoleia, etc. The term " Grit " has locally been 

 applied to rubbly oolitic stone, often a hard ragstone or limestone unfit for build- 

 ing-purposes. Trigonia signata [decorata] occurs in the Upper Trigonia Grit. 



The Pea Grit Series includes certain beds of coarse ferruginous oolite and 

 freestone^ (Lower Limestone), which occur below the Pea-grit, at Stroud, etc. A 

 variety of Rhyuchonella cynocephala has been found in this Series and also in the 

 Oolite Marl. 



The Pea-grit or Pisolite is composed of flattened spheroidal masses about the 

 size of a pea, and one-fourth or one-fifth of an inch in diameter. Many of the 

 ovules consist of layers of carbonate of lime, aggregated around some organic or 

 inorganic fragment : some appear to be small rolled fragments of limestone. This 

 division is very fossiliferous : it contains Terebratnla simplex, T. plicata, etc. It 

 extends from Leckhampton, by Birdlip and Stroud to Selsley and Nailsworth. 



The beds which rest on the Pea-grit are, according to Prof. Hull, frequently 

 pierced by Lithodomiis atUnuatus : the upper bed of the Ragstone is also bored 

 by Lithodomi. 



Between Cheltenham and Chipping Campden the Inferior 

 Oolite covers an extensive area; and it occurs on Bredon Hill. 

 Near Bourton-on-the-Hill the Clypeus grit (36 feet) is underlaid 

 by freestone bored by Annelides, and is not far removed from the 

 Upper Lias. 



East of Cheltenham the Inferior Oolite rapidly diminishes in 

 thickness. (See Fig. 43.) It is represented in the neighbourhood 

 of Woodstock by only 5 to 10 feet of the highest member of the 

 series. At Sarsden the thickness is about 20 feet; at Fawler, near 

 Stonesfield, 1 feet ; at Enstone there is only a trace ; and along 

 the valley of the Cherwell it is altogether absent. 



To the south and south-west of Cheltenham the Inferior Oolite 

 also diminishes in thickness ; at Haresfield Beacon, west of Paifis- 

 wick, it is about go feet, ^ but the full thickness near Stroud is about 

 150 feet. The beds may be well studied at Stroud Hill and at 

 Rodborough Hill to the south of Stroud. At Dundry Hill, where 

 the zones of A. Parkinsoni, A. Humph riesianus, and A. ]\IurchisoncB 

 are represented, the Oolite is upwards of 40 feet ; and at Bath 

 it is about 25 feet thick, but here Avimonites are by no means 

 abundant. From Dundry a specimen of A. siihradiatus obtained 

 with its operculum in situ, was described by Dr. S. P. Woodward.^ 



In thickness and lithological character the Inferior Oolite varies 

 much in Somersetshire ; near Radstock and Frome it is a pale 

 oolite, very cherty in places near the latter town.* In the combes 

 near Frome, at Vallis, Whatley (see Fig. 41, p. 253), Nunney, 

 Holwell, and Little Elm, the Inferior Oolite rests sometimes on 

 the Rhcetic Beds, sometimes directly on the Carboniferous Lime- 

 stone or Old Red Sandstone ; and it is in places conglomeratic, 

 containing pebbles of quartz from the Old Red Sandstone, etc. 



1 E. Witchell, Geology of Stroud, 1882, and Q. J. xlii. 234; see also P. B. 

 Brodie, Q. J. vii. 210. 



* J. Buckman, Q. J. xxxv. 737. 

 ^ Geologist, iii. 328. 



* J. McMurtrie, Proc. Bath Nat. Hist. Club, 1883. 



