Geological Society of London. 47 



2. " On the Geology of North-west Lincolnshire." By the Eev. 

 J. E. Cross, M.A., F.G.S. 



The district treated of is that lying between the three rivers, 

 Plumber, Trent, and Ancholme. The Liassic and Oolitic beds were 

 described, from the Keuper (found in the bed of the Trent) to the 

 Cornbrash (the highest Oolitic stratum existing on this line). The 

 existence of the Khtetic beds was held to be doubtful ; the bone- bed 

 and the shell Avicula contorta have not been found. On the other 

 hand, the Lower Lias has a large development ; and the recently 

 discovered Ironstones of Frodingham and Scunthorpe were shown 

 to lie in this formation, the zone being that of Amm. semicostatus. 

 Higher up the series the zone of Amm. margaritatus seems to be 

 wholly wanting, and the Marlstone series has dwindled to a bed of 

 8 feet in thickness, locally termed the Bhynchonella-hed. The Upper 

 Lias is represented by clays not much explored. 



As regards the Oolites, the " Lincolnshire Oolite" is the prevailing 

 rock ; but a lower band, called " Santon Oolite," was distinguished 

 from it, containing a different fauna. Above the Lincolnshire Oolite 

 a greenish clay, capped by Cornbrash, represents the great Oolite 

 formation; and beyond this the alluvium of the Ancholme valley 

 covers everything, till the Chalk rubble and the Chalk wold rise 

 above it to the eastward. 



Discussion. — Mr. Etheridge spoke as to the excellence of the paper, which 

 contained a most useful collection of facts. Two of the species of Ammonites 

 exhibited were rare, being new to Britain, and only previously known in France 

 and Germany, showing and confirming the wide distribution in space of certain 

 forms of this group. An important feature in Mr. Cross's paper consisted in his 

 determining and correlating the zones of life in his area with those of the south and 

 west of England, especially as regards the lowest part of the Lower Lias. The 

 fixing the true position of the Frodingham ironstone and' its associated Fauna, 

 fully establishing its place, thickness, and value, and finally settling the point at 

 issue as to its being on the same horizon as the "Cleveland seam," is also of high 

 importance. 



Mr. Judd remarked on the interest attaching to this communication, not only as 

 describing a district but little known to Geologists, but also as furnishing us with 

 evidence of very fine developments of geological horizons which, elsewhere in this 

 country, are represented only in a very imperfect manner, or not at all. 



Mr. J. F. Blake remarked that though the author had found no exposure of 

 beds between the Angulatus-zoue and the Keuper, they probably existed, as they 

 occurred both to the south and to the north in Yorkshire, across the Humber. He 

 agreed with the author that the ironstone of Lincolnshire was on an entirely 

 different level, and was totally unrelated to that of Yorkshire, the true equivalent 

 of which, though here only eight feet, was much thicker, though not valuable, 

 across the Humber. The Pecten-beds mentioned were characteristic of the same 

 zone in Yorkshire as in Lincolnshire ; but in the former county they contained no 

 iron except in the form of pyrites. The thinness of the upper beds, as contrasted 

 with the thickness of the lower, showed a veritable thinning out of them, which 

 was continued into Yorkshire, where some of the fossiliferous bands of the Inferior 

 Oolite described by the author appear to be altogether wanting. 



Prof. Hughes said that he thought we should be careful not to infer too hastily an 

 interruption in the continuity of deposition from the absence of certain fossils from 

 the horizon at which they occur in other sections. 



