1856.] TVRIGHT — UPPER LIAS SANDS. 293 



LeckhamptoD, Birdlip, and Painswick Hills thin out and almost dis- 

 appear in a run of less than twenty miles from these typical sec- 

 tions. If we trace the so-called " Sands of the Inferior Oolite " 

 from Cheltenham southwards, we find them gradually thickening as 

 we proceed by Crickley, Cooper's, and Painswick Hills, to Beacon, 

 Frocester, awd Wotton-under-Edge, where fine sections are exposed. 

 The oolitic limestones, including the pea-grit, upper and lower free- 

 stones, and the intervening oolite marl, which are about 190 feet 

 thick at Leckhampton, gradually diminish in thickness near Stroud, 

 and in the neighbourhood of Bath are represented by about 60 feet 

 of freestone, the pea-grit and oolite-marl having entirely thinned 

 out. 



The upper ragstones, including the Gryphsea-bed and the Tri- 

 gonia-bed, have a more constant and uniform development through- 

 out the tract of the Inferior Oolite, and present a similar suite of 

 fossils wherever they are exposed ; being always well characterized 

 by Ammonites Parkinsoni, Sow., A. Martinsii, d'Orb., Trigonia 

 costata. Sow., Perna rugosa, Goldf., Clypeus sinuatus, Leske, Col- 

 lyrites ringens, Desml., Holectypus hemisphcericus, Desor, H, de- 

 pressus, Klein, Terehratula globata. Sow., T. sphceroidalis, Sow., 

 Rhynchonella plicatella. Sow., and R. spinosa, Sow. 



The Fuller's Earth is represented by a thin band of clay near Chel- 

 tenham ; it is 70 feet thick near Stroud, 128 feet near Wotton-under- 

 Edge, and forms a conspicuous bed, 150 feet thick, near Bath. 



In Somersetshire and Dorsetshire the Sands attain a great thick- 

 ness, and form an important feature in the physical geography of the 

 oolitic districts of these counties. Wherever they are well exposed, as 

 in the sections about to be described, they are overlaid by a bed 

 of coarse, brown, marly limestone, full of small, dark, ferruginous 

 grains of hydrate of iron, imparting an iron-shot aspect to this rock, 

 which in general contains an immense quantity of individuals of seve- 

 ral species of Ammonites, Nautili, and Belemnites, with a few shells 

 of other Mollusca. Beneath this fossiliferous band, or " Cephalo- 

 poda-bed," are the so-called " Sands of the Inferior Oolite," con- 

 sisting of very fine, brovra and yellow, calcareous sands, often mica- 

 ceous, and well adapted for foundry-purposes, as they receive sharp 

 impressions of bodies pressed upon them. They contain in their 

 upper part inconstant layers of siliceo-calcareous sandstone, and 

 sometimes in their lower part large inconstant concretionary masses 

 of coarse sandstone, the lowest beds becoming blue and marly, and 

 passing insensibly into the clays of the Upper Lias. The line of 

 junction is easily detected by the springs of water which burst out 

 immediately above the clays. The sands themselves are not fossili- 

 ferous, but the nodules sometimes lying near their base often con- 

 tain organic remains. 



As it is the object of this memoir to show, that the Cephalopoda- 

 bed contains a number of well-known Upper Liassic Ammonites, 

 Nautili, and Belemnites, and that the weight of paleeontological evi- 

 dence is in favour of the supposition, that it belongs to the Lias, 

 rather than to the Oolite-formation, I purpose to describe five sec- 



