A. E. Trueman — Tlie Lias of South Lincolnsliire. 65 



the south-western part of the area lias been resurveyed and described 

 in more recent memoirs. A summary of the geologj' of the area 

 was prepared in 1910 by A. J. Jukes-Browne,^ but except for these 

 publications the literature is scattered and consists mainly of short 

 papers ; details of these are given where they are referred to. 



It will therefore be seen that the Lias as a whole has not been 

 studied in this neighbourhood for some thirty years. During this 

 time the Lias of other areas has been carefully investigated by 

 numerous workers, resulting in great advancement in our knowledge 

 of the succession. This work has been undertaken in order to deter- 

 mine whether the Lincolnshire succession agrees with that recorded 

 elsewhere. 



Since there are no continuous sections available for study, the 

 work has been confined to artificial exposures in limestone and 

 ironstone quarries and clay pits. Many of the exposures examined 

 by previous writers have long been abandoned, owing to the closing 

 of the hand-brickyards in the area ; " moreover, on account of the 

 war, many of the remaining yards have been temporarily closed, 

 and consequently it is often a matter of some difficulty to collect 

 fossils in situ. Thus it may be expected that the fauna! lists will 

 be considerably increased and much fresh detail obtained by further 

 work when the pits are reopened. "While only scattered observa- 

 tions may be made on the Lower Lias clays, it has been possible to 

 make a detailed comparison of the Middle and Upper Lias. In the 

 course of the work samples of clay from each exposure have been 

 "washed" and the residue examined for Foraminifera, details of 

 which ar£ given in the lists. 



It is necessary to state tliat the interpretation of "zone" adopted 

 in this paper is that given by Mr. W. 1). Lang,^ who emphasized the 

 fact that once a zone is defined its boundaries " theoretically are 

 fixed for ever". The so-called zones which have been used at 

 Lincoln have often been unsatisfactory ; for example, the deposits 

 known as commune zone in Lincolnshire and Yorkshire are quite 

 different in age. If zonal terms were correctly used, such a contra- 

 diction would be impossible. In this paper the hemeral terms 

 introduced by Mr. S. S. Buckman, which have sometimes been 

 miscalled zones, have in the Upper Lias been used as sub-zones of 

 Oppel's cumbersome zone of Posidonomya Bronni. 



In the course of this work much help has been received from 

 numerous workers in Lincolnshire, especially Mr. A. Smith, of 

 Lincoln Museum, and Mr. H. Preston, of Grantham, who generously 

 placed at my disposal their detailed knowledge of the district. For 

 permission to examine specimens I am also grateful to Mr. Gr. W. 

 Laraplugh and Mr. H. A. Allen, of the Jermyn Street Museum 

 (Geological Survey) ; and to Mr. E. E. Lowe, of Leicester Museum. 

 Mr. S. S. Buckman has kindly named several ammonites and assisted 



^ Lincolnshire, Jubilee Vol., Geol. Assoc, 1910. 



^ A. E. Trueman, "Lias Brickyards in South-West Lincolnshire " : Trans. 

 Lines Nat. Union, 1917. 



* W. D. Lang, " Geology of Charmouth Cliffs, etc." : Proc. Geol. Assoc, 

 1914, p. 307. 



DECADE VI. — VOL. V. — NO. II. 5 



