66 A. E. IVueman — TJce Lias of South Lincolnshire. 



in other ways. Much help in the field has heen given by Messrs. 

 W. E. Howarth and W. D. Varney, while at all stages of my work 

 Professor H. H. Swinnerton has offered advice and encouragement, 

 for which I am greatly indebted. I have also to thank Professor 

 T. F. Sibly for reading ray manuscript and making various suggestions. 

 The general succession of Liassic rocks in this area is as follows: — 



Feet. 

 Upper Lias. Shales with concretions . . about 100 



Thickness decreasing northwards. 



(No higher beds than the subzone of subcarinatum 

 are present at Lincoln, and the subzone of 

 fibulatum at Grantham.) 

 Middle Lias. a. Marls and Ironstone (present in South 



Lincolnshire. Only thinly represented around Lincoln). 3-30 



b. Shales 30-70 



Lower Lias. a. Blue, black, and grey shales, with 



nodules and bands of earthy limestones . about 700 



b. Hydraulic limestones ... 25 



It will be most convenient to consider the rocks in the following 

 order : — 



1. Hydraulic Limestones. 



2. Lower Lias Clays. 



3. Middle and Upper Lias. 



(«) Lincoln, {b) Grantham. 



1. Hydraulic Limestones. 



The number of Hydraulic Limestone quarries now being worked 

 is considerably smaller than it was a few years ago, but Lias 

 cement is still made at Barnstone, Owthorpe, and Barrow-on-Soar ; 

 a large quarry near the railway at Normanton Hills, East Leake, 

 has only recently been abandoned, and a complete section of the 

 beds from the Keuper to the Lower Lias is still visible, while the 

 junction of Phaetic and Lias is also exposed at Cotgrave Gorse. 

 The limestone quarries east of Newark have not been worked for 

 several years, and in only one of these is the succession clear. 

 However, the construction of trenches at the Royal Engineers' Depot 

 at Coddington has made it possible to study the sequence, in the 

 Newark neighbourhood. Colonel H. Jerome kindly gave permission 

 to study this section. 



An examination of the available sections and a comparison of the 

 diagrams which have been constructed, as suggested by the late 

 Dr. Vaughan,* to show the ranges of the fossils, indicates that there 

 are three types of transition from Rhaetic to Lower Lias in this 

 district, viz. : — 



1. The type seen at Owthorpe, a full account of which was given in 

 a previous paper ;■ it was pointed out that the lowest beds do not 

 contain Fsiloceras planorlis, the zonal ammonite, which is likewise 

 absent in the lowest beds at Cotgrave Gorse, Normanton Hills, 

 Barnstone, and Newark. T. Wright noticed that in the South of 



^ A. Vaughan, " Lower Beds of the Lower Lias of Sedbury Cliff " : Q.J.G.S., 

 vol. lix, p. 396, 1903. 



'^ A. E. Trueman, "Fauna of the Hydraulic Limestones " : Geol. Mag., 

 Dec. VI, Vol. II, p. 150, 1915. 



