Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/311

1870.] LLOYD — AVON AND SEVERN VALLEYS. 203 the Avon Valley, near Cropthorne in "Worcestershire, which are referred to by Sir R. I. Murchison in his ' Silurian System.' My own investigations are merely an extension of those commenced by Strickland, to whose writings I am much indebted for valuable information, and many suggestions.

In July 1868, a paper was read by Mr. E. Cleminshaw, at a meeting of the Nat. Hist. Society of Rugby School, on the river-gravels of the Avon in the neighbourhood of Rugby ; and this was followed in the published report by a note written by Mr. Jas. M. Wilson, F.G.S., which I recommend as worthy of the attention of all who are studying Postpliocene geology. I must also refer to a short paper by the Rev. P. B. Brodie, F.G.S., called " Remarks on the Drift in a part of Warwickshire" (Quart. Journ. Geol. Soc. vol. xxiii.). In Sir R. I. Murchison's chapters on Drift, in the ' Silurian System,' the subject of the northern drift is extensively worked out.

General description of the River and Valley of the Avon. — The

Fig. 1. — Section across the Valley of a Tributary of the Avon. Distance 2 miles.

S.W. N.E. Railway- Rugby, cutting. Stream. Clifton. Sea-level.

a, a, a. Drift of Upper series. b. Alluvium. c, c. Lower Lias clay and limestone.

river Avon rises near Naseby, in Northamptonshire, whence, taking a south-westerly course by Rugby, Warwick, and Stratford-on-Avon, it flows past the town of Evesham through a narrow bend of the valley, below which it enters a broad alluvial plain, and, following a tortuous course by Fladbury, Cropthorne, Pershore, and Defford, finally enters the Severn at Tewkesbury, having accomplished a distance from Rugby, as measured along the valley, of about sixty-four miles. Its principal affluents are the Swift, the Leam, the Arrow, and the Bow. The basement rocks, which belong to the district of the valley between Rugby and Tewkesbury, occur in the following order : — Lower Lias limestone and clay from Rugby to King's Newnham ; New Red marl and " waterstones" from King's Newnham to Cloud Bridge ; Permian conglomerate from the latter place to within a few miles of Warwick, where the Keuper series reappears ; between Stratford-on-Avon and Tewkesbury the Lower Lias clay predominates, the Keuper marls occupying only a narrow area of about six miles in width between Stratford and Evesham, and occurring again on a line of fault near Fladbury. Bredon Hill is an outlier of Blue Lias clay and Inferior Oolite.

Description of Transverse Sections. — In a section taken across the valley of a tributary stream between Rugby and Clifton (fig. 1), a, a, a represent beds of Boulder-clay, quartzose flinty gravel