320 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Juiie 15, 



ing in size from 8 to 1 2 inches in diameter to pebbles of the size of 

 a pin's head. The clay also contains large boulders of oolitic and 

 other rocks, arranged in somewhat parallel lines, the former being 

 very abimdant. The lower part, 30 feet thick, consists of dark bluish 

 grey tenacious clay, with traces of chalk and flints, and but few 

 boulders. These latter are generally large and much rolled, and 

 have been derived from the Oxford clay, oolites, marlstone, and lias ; 

 there are also pebbles of mountain limestone, granite, and other rocks ; 

 and interspersed with these are numerous liassic fossils, as Am- 

 monites, Belem7iites, Gryphcea, Pholadomya, &c. At the junction of 

 these two divisions the boulders and pebbles occur in greater abun- 

 dance, lying on an apparently eroded surface of the lower drift, which 

 is readily distinguished from the upper division by the comparative 

 absence of chalk and flint. 



Emerging from the south end of the tunnel, which is 880 yards in 

 length, we see the drift on either side of the cutting buoying up an 

 enormous irregular mass of oolitic rock, through which the cutting 

 has passed (see fig. 1, o). This mass of rock is 430 feet long, and, at its 

 deepest part, 30 feet thick ; it is much broken and disturbed, but the 

 parts retain to some extent their relative position, and belong to the 

 lower portion of the oolitic beds of the district : the surface is continu- 

 ous with the hill slope, and is here and there penetrated by intrusive 

 drift ; the lower part is eroded and waterworn. The depth of the 

 underlying drift exposed at the lowest part between the broken rock 

 and the level of the railroad is about 7 feet. Unfortunately the cha- 

 racter of the neighbouring surface is so much obscured, that it is 

 difficult to estimate the lateral extent of this great mass of disturbed 

 oolite, which, although so distinctly isolated, retains sufficient uni- 

 formity of character to lead us to infer that it has not been far re- 

 moved from its original site. The drift is here of similar character 

 to the upper portion at the north end of the tunnel, and is pecu- 

 liarly marked by boulders (oolitic chiefly) more or less horizontally 

 arranged, and some of them underlying the uplifted mass of oolite. 



Section A. Basinc/thorpe Cutting. — Crossing another denuded drift 

 valley, we come to the Basingthorpe Cutting, which extends for about 

 one and a half mile through drift similar to the above. The larger 

 boulders are more abundant ; thirty to forty were counted in about 

 sixty yards. They varied in size from 1 to 3 or 4 feet ; one however, 

 a micaceous sandstone, with fossils, much grooved and striated, mea- 

 sured 6 feet 9 inches in its longest diameter and 3 feet in depth. 

 They are generally more or less square in form, and lie on their flat 

 side, are sometimes polished, and frequently grooved or striated ; 

 the striae are restricted to their flat surfaces, and are not found on 

 the edges. The boulders assumed, as before noticed, a horizontal 

 arrangement, somewhat following the contour of the surface of the 

 ground. The larger masses consist of micaceous sandstone con- 

 taining fossils (marlstone and cornbrash), besides which are many 

 rounded and angular flints (sometimes grooved), lias septaria, green- 

 stone, mountain-limestone, coarse sandstone, lias and chalk belem- 

 nites, and other fossils ; occasionally we meet with local patches 



