398 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 6> 



mences. We here find the beds rising with the hill, and consisting, 

 1st, of thirty feet of brownish laminated clays (A) underlaid by 

 twenty feet of dark-coloured laminated clays and shales (B). The 

 cutting is continued in these beds to the entrance of the tunnel on 

 the north, and through the tunnel for about 300 yards ; on the 

 south side of the tunnel we see the lower portion of the same clays 

 occupying the upper part of the cutting and gradually cropping out, 

 giving way to the important sandstone beds which rise from below 

 them. The dip of these argillaceous beds being about 2° or 5° 

 north, their probable thickness is about 170 feet. 



The mass of the clay is of a dark bluish grey colour, occasionally 

 greenish, finely laminated and shaly, and it contains several very 

 thin bands of dark impure argillaceous limestone, some tabular and 

 others ferruginous and concretionary, and we also find in them thin 

 tablets of clayey sandstone. The organic remains of these beds are 

 exceedingly abundant; the thin limestones are full of Cyrena media, 

 Paludina elongata and Cypris Valdensis. The same species are 

 also common in the clays, but the abundance of the Cypris in them 

 is a remarkable feature, generally producing a lamination of extreme 

 thinness entirely covering every freshly separated surface. The 

 shelly coverings of the Testacea and Cyprides are better preserved in 

 the clays than in the limestones, but they are frequently crushed and 

 always very friable. Singular vermiform impressions are also found 

 on some of the more indurated clays, and may be especially observed 

 covering the surfaces of the impure sandstone tablets. 



Underlying these clays are three beds of light-coloured sandstone 

 (C) separated by dark brown clays, forming a thickness of twenty 

 feet, and containing the Unio Gaulteri and Cyrena subquadrata 

 and imperfect impressions of plants. 



The next division (D), although conformable in general stratifi- 

 cation, presents a slightly uneven and water-worn line of separation 

 with stratum C (see general section, fig. 1, at point «), a fact cor- 

 roborative of some change of condition, as further evinced by the 

 almost entirely arenaceous structure of this lower division in con- 

 trast with the generally argillaceous characters of the upper ones (C 

 and B). This structure is rendered very visible by the dark brown 

 colour of the lower part of the upper division, and the nearly pure 

 white of the clayey sand forming the upper bed of the lower divi- 

 sion. This sand is underlaid by two feet of black lignite clay ; be- 

 low this clay is a series of sixty to seventy feet of thick-bedded 

 light-coloured sandstones (D), sometimes massive, at other times fis- 

 sile, and occasionally exhibiting false stratification. Many of the 

 upper beds of this division, although apparently firm and compact 

 when first exposed, decompose readily by exposure to the atmo- 

 sphere in consequence of the base of the sand-rock consisting of 

 fine white clay. About fifty feet from the top of this division is a 

 strongly-marked band of lignite clay from eight to twelve inches 

 thick, which rises from the base of the cutting ten or twelve yards 

 on the north side of the forty-second nn'le-post ; the beds of sand- 

 rook about ten feet al>ove and below this lignite band are slightly 



