INFERIOR OOLITE. 289 



Cephalopoda-bed (4 to 16 feet) is sometimes bored by Lithodo7nus. 

 The beds are very well developed at Nailsworth and Frocester 

 (150 feet), and the names of these places have been locally used to 

 designate the Sands. They are also to be seen at Wotton-under- 

 Edge, Crickley Hill, Haresfield, and other localities.^ (See Fig. 44.) 



The soil on the Midford Sands is generally fertile. Some of the concretionary 

 masses are used for building-purposes, and Dr. Wright has stated that the sands 

 are " well adapted for foundry purposes, as they receive sharp impressions of 

 bodies impressed upon them." 



The Ham Hill Stone is one of the best building-stones in the west of England, 

 and has been quarried for many centuries. It is of a light brown colour, due to 

 the presence of carbonate of iron. Montacute House and Brympton Hall near 

 Yeovil, as well as most of the churches in the neighbourhood, are fine examples of 

 buildings constructed of this stone. Similar stone is quarried at North Perrot, 

 near Crewkerne. 



The Sands form conspicuous grassy knolls in the neighbourhood of Bridport, 

 Colmer's Hill to the west of that town being a prominent feature; Glastonbury 

 Tor and Brent Knoll are still more striking examples. (See remarks on sandy 

 lanes, in sequel. ) 



INFERIOR OOLITE. 



The Inferior Oolite consists of buff and brown oolitic and iron- 

 shot limestone, with marly and sandy layers, and occasional beds 

 of compact limestone. It is generally darker in colour than the 

 Great Oolite, and was termed the Under Oolite by William Smith 

 in 1812, and the Inferior Oolite by James Sowerby in 1815. 

 In thickness it varies from 15 feet on the Dorsetshire Coast to over 

 230 feet near Cheltenham. The fossils of the Inferior Oolite vary 

 much in different localities, but from Gloucestershire to Dorset- 

 shire the four Ammonite-zones may at intervals be determined. 

 The succession is well borne out, and yet sometimes one or more 

 zones may be absent, or the beds may be unfossiliferous. 

 Occasionally A. Parkinsoni, and A. Humphriesianus may be met 

 with together. By some authorities the zone of A. Soiverbyi is 

 regarded as a subzone of that of A. Murchisonce (a species named 

 in honour of Lady Murchison). In some quarries Cephalopods 

 are very abundant, in others Lamellibranchs, or Brachiopods are 

 the prevailing forms ; but Ammonites and Brachiopods are per- 

 haps the most characteristic of particular horizons. 



In the zone oi Ammonites Parkinsoni there occur ^. snhradiatus, 

 Terehratida global a, T. sphceroidalis, T. perovalis, T. Phillipsii, 

 Rhynchonella spinosa, R. siiblelrahedra, etc. In the zone of A. 

 Humphriesiajius we find A. Blagdeni, A. Marlinsii, Waldheimia 

 carinala, etc. In the zone of ^. lilurchisoncB there are A. Soiverbyi, 

 A. co7icavus, Terebralula fiinbria, T. si??iplex, T. plicala, Rhynchonella 

 subobsoleta, etc. 



Among the other fossils are Sponges ; also the Corals, IsaslrcBa, 

 Lalimceandra, Monllivallia, etc., and the Echinoderms, Holectypus 



^ P. B. Brodie, Q. J. vii. 210; T. Wright, P. Geol. Assoc, iv. 16S ; E. 

 Witchell, Geology of Stroud. 



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