Page:Quarterly Journal of the Geological Society of London, vol. 35.djvu/881

Rh PKOF. J. BTTCKMAN ON THE HIDFOKD SANDS. 741 working as the Ham-Hill section. This latter is the highest and deepest-worked of the series. Section at Mr. Trash's Quarry, at Doidting. 1. The upper beds denuded "I ft. in. 2. Thin-bedded white freestone, more or less made up of comminuted 1 10 shells J 3. Blocks of freestone used for best building-stone 25 This section shows that the Ham-Hill equivalent has been denuded from the upper part of the quarry, while the beds below the freestone are covered up ; but, judging from the district, we conclude that the building-stone is underlain by the blue or grey bed, and this, again, by some sands. At Hilborne Wyck we have beneath the fossiliferous or Cephalo- poda-bed beds much of the same character as those at Doulting ; but here the colour is neither foxy nor wholly white, but is occasionally tinctured with green grains, probably derived from some phosphatic salt. Prom these remarks it will be seen that the composition of the bed under review is so very variable that the mistakes made in its reading may be easily accounted for, as the difference between a thick rock of yellowish sand only occasionally interrupted by bands and pot-lids of shelly oolite occupying a thickness of over 100 feet. The ochraceous building-stone at Ham Hill and the Doulting beds, as also their equivalents in Gloucestershire, are of about the same thickness. The differences here noted, then, are very marked, so far as lithological structure is concerned ; the thicknesses at the same time very nearly accord. It is not true, then, that " the Inferior Oolite, which near Yeovil immediately overlies the sands, is com- paratively thin, in consequence of the absence of the thick-bedded limestones which impart such a thickness to this formation in Gloucestershire" *. The so-called Midford Sands, the sands at Bradford and near Sherborne, together with the building-stones at Ham Hill, Doulting, and other places, are neither more nor less than Inferior Oolite, as they are all on the same horizon as the middle and lower beds of this rock which are so well exposed over the Cotteswolds. Now inasmuch as the sands to which Prof. Phillips gave the name of "Midford Sands" are not the same as the sands in Glouces- tershire, but belong to a higher (Oolitic) series of beds, the proposed name will in no wise solve the difficulty ; and we feel convinced that had Prof. Phillips been made acquainted with the true nature of the sands of Somerset and Dorset, as now explained, he would never have proposed it. We look upon it, then, that the Inferior Oolite is of about the same thickness in Somerset and Dorset as in Gloucestershire ; there is no missing link, as some have attempted to" explain ; still, however, the lithology differs from that of the Cotteswolds, but not more than may be observed in different parts of the Cotteswolds themselves, or
 * Quart. Journ. Geol. Soc. vol. xvi. p. 34.