116 



REV. J. E. CROSS ON THE GEOLOGY OF N.W. LINCOLNSHIRE. 



The accompanying section (fig. 2) gives a general idea of the 

 district. Three escarpments are represented, and two long sloping 



Fig. 2. — Section from the Chalk Wolds of N. W. Lincolnshire to the 



River Trent. 



a. Cornbrash and Great-Oolite clay. 



b. Lincolnshire Limestone. 



c. Upper Lias clay. 



d. jRhynchonella-bed. 



e. Capricornus-Gl&j — Middle Lias. 

 /. Pecten-bed. 



g. Lower Lias clay. 



h. Scunthorpe Ironstone. 



i. BucMandi-be&s. 



7c. Infra-Lias. 



I. Keuper. 



plains between them. The westernmost scarp is capped with Lower 

 Lias (BueJclandi-zone) , the middle one with Lincolnshire Limestone; 

 and the easternmost is the Chalk Wold. Both these latter elevations 

 are characteristic and enduringfeatures in the county. The limestone- 

 ridge is called the " Cliff," and rnns pretty nearly due south from the 

 Humber to Lincoln, and further. The wold trends S.E. towards 

 Boston and " The Wash." The westernmost elevation of the three 

 is not so continuous. What I desire to do now is to give a slight 

 sketch of the Liassic and Oolitic strata here exhibited, from west to 

 east, from the lower rocks to the higher. 



The bed of the river Trent is in the Keuper Marls (fig. 2, 1). When 

 a railway-bridge was built here a few years back the sinkings for the 

 piers were all through this formation. 



It would be natural to suppose, then, that the Bhsetie beds would 

 make their appearance on the eastern shore, especially as they have 

 been found well developed elsewhere in the county ; but I have as 

 yet no sufficient proof of their existence. Nor do I find any trace 

 of the famous bone-bed, nor, again, any single specimen of Avicula 

 contorta, for which I have searched very diligently. Nor have I 

 seen any one specimen of the true Ammonites jplanorbis. As far as 

 my researches go, the first strata next above the Keuper are those 

 which contain Ammonites angulatus and A. Johnstoni ; and if this 

 is so, a considerable gap in the series is exhibited. As regards these 

 two Ammonites, both appear together in the lowest beds (figs. 2 &S,k); 

 but A. angulatus seems to reach far above the extreme limit of the 

 other, throughout a zone of, say, 150 feet or more. 



