Page:Quarterly Journal of the Geological Society of London, vol. 32.djvu/296

216 216 W. J. HARRISON ON THE OCCTJRREXCB

rapidly along the crest of the hill, prevents further investigation. The existence, however, of beds higher in the series is shown by the occurrence of blocks of limestone in the drift, with Monotis decussata and Anoplophora musculoides.

I have found further traces of the Rhaetics at a point about a mile north of the Spinney Hills, near the site of the Borough Asylum ; and I believe Mr. R. Etheridge, E.R.S., has noted their occurrence at a spot about 9 miles further north between Barrow and Sileby. I noted them here during the widening of the Midland main line in 1873, and the section is mentioned by Mr. H. B. Woodward (Geol. Mag. 1874, p. 480).

Still further to the north-east the same beds have been cut through near Stanton by the railway now in course of construction from Nottingham to Melton ; but here, again, the higher Rhaetic beds seem to have been much denuded. The nearest southern exposure seems to be at Copt Heath, near Knowle, in Warwickshire, as noted by the Rev. P. B. Brodie (Quart. Journ. Geol. Soc. vol. xxx. p. 746).

In the deep boring for water at Rugby the Rhaetics were reached at a depth of about 450 feet. The black shales were there 8 feet thick, and the hard sandy marls beneath about 10 feet.

Although good sections of the Rhaetic beds are rare in Leicester- shire, yet the line of outcrop of the strata can be clearly traced from Leicester northwards, forming the eastern boundary of the Soar valley, and varying from a quarter to about half a mile in width. Southwards the great thickness of drift makes an exact tracing difficult.

At Crown Hill (fig. 2) I have lately detected, in the preliminary works for the Great Northern line from Melton to Leicester, certain beds of limestone, called in Warwickshire the "Firestones" and " Guineas/' wljich mark the passage of the Rhaetics into the Lower Lias, together with a thi^.k bed which is probably true White Lias. The cutting here will, I believe, exhibit a very interesting series of beds, and enable us to trace the succession for a long way up.

Wherever the true junction of the Lias and Trias is exposed in this country, the Rhsetic beds appear to be invariably present. In 1874 I examined a fine section exposed in widening the Midland main line between Leicester and Wigston, which seemed to contra- dict this ; Lower Lias Shales and Limestones, with Ammonites planorbis, appeared to be resting on Upper Keuper Marls. A close examination of the latter, however, showed them to be recomposed stuff; the Rhaetics had been eroded, probably by glacial action, and their place filled with transported material.

I am much indebted to the Rev. P. B. Brodie, Messrs. W. H. Hudleston, W. Davies, L. C. Miall, C. Moore, and others, for their kind assistance in the determination of specimens.

The students in my science classes, especially Messrs. J. E. Elgood, J. R. Plant, L. H. Llewellyn, and W. J. Harrison, jun., have ren- dered valuable aid in searching the beds.