J. a. Cooke — Section in Middle Lias, Lincoln. 255 



he notes that " its disappearance is remarkable as it is known at 

 Leadenham, ten miles to the south, though rapidly thinning out, 

 and it occurs also some distance north of Lincoln." 



It was this impersistence that lead Mr. Carr to infer the entire 

 absence of this bed at Lincoln. As I shall presently show, however, 

 the Marlstone occurs both in this and in the adjoining disused pit 

 of Glaisiers. But although the sequence of the beds in the different 

 pits varies so much, little difficulty is experienced in determining in 

 a general way the equivalence of conditions in the different localities, 

 as there are several horizons, e.g. layers 11, 17, and 18 to 30 (see 

 section, p. 254), that are strongly marked, and as far as I have 

 been able to determine they are also fairly constant. 



In the cutting that has recently been made on the slopes that 

 intervene between the pit of the Lincoln Brick Company and that 

 of Handley, the top becl of the Middle Lias, which is overlain by the 

 basement " Fish and Insect " Limestones of the Upper Lias, is well 

 exposed. This " Fish and Insect " bed consists of a stratum of soft 

 ferruginous, arenaceous, finely laminated, and very fissile limestone 

 of a yellowish colour, weathering grey. It has associated with it 

 numbers of compact limestone nodules that are traversed with 

 minute veins of calcite, and crowded with the remains of small 

 corals [Astrea), Belemnites, Ammonites anmdatus, Viscohelix aratus, 

 and small Gasteropods {Turritella and Chemnitzia) . 



The bedding planes of the limestone are crowded with the casts 

 and shells of Inoceramiis dubius, Sow , and also with great quantities 

 of golden-coloured particles of the shells of this mollusc that bear 

 in some cases a strong resemblance to the scales of fishes and the 

 wings and elytra of beetles. Casts of Astarte, sp., Lima, sp., the 

 burrowings of Annelids, and fragments of calcified and pyritized 

 wood, are also common. The Ammonites and Gasteropods are often 

 found filled with calc-spar. 



Beneath this lies a bed of blue shaly clay that is highly pyritous 

 and thinly laminated, and has an intercalated band of ferruginous 

 limestone nodules. These nodules are very rotten, and having a 

 concentric structure they readily peel and break up. They are quite 

 unfossiliferous. The pyritous state of the shale does not appear to 

 have been favourable to the preservation of fossils, and notwith- 

 standing a careful search I was unable to find any traces of 

 organic life. 



At the bottom of this cutting the tram-lines have been laid on 

 a bed of soft ferruginous sandstone that varies considerably in its 

 petrological characters. At the north end of the cutting it is compact 

 and massive; at the south end it is very soft and friable. This 

 sandstone readily splits into thin slabs, the bedding planes of which 

 show A. spinatus, A. serpentinus, A. Thourense, Belemnites clavatus, 

 Ditrupa liassica (five inches long), and casts of Lima, Pecten, Leda, 

 Cardium, and Nucida. 



Below this is a series of alternating beds of clays, shales, nodular 

 seams, and limestone bands, but in none of them are the conditions 

 favourable to the preservation of organic remains. 



