Vol. 55.] GEOLOGr OF THE GEEAT CENTRAL EAILWAT. 67 



II. Desceiption of the Sections. 



Considering the undulating character of the country passed through, 

 the cuttings are of very moderate depth, the reason for which will 

 be obvious on inspecting the sections (figs. 1-5) ; but they are all 

 through Glacial deposits or Lower Lias. 



The longest, and that which we shall examine first, if we proceed 

 from north to south, in order to follow the various strata, so far 

 as possible, in chronological sequence, is the section near Rugby, 

 extending from about 52 miles 40 chains to 54 miles 20 chains : 

 that is, approximately 1| mile. In the deepest part, near where the 

 Hillmorton & Dunchurch road crosses it, it is about 45 feet deep. 



Erom A to B (fig. 1, p. 66) is embankment ; B to C, a viaduct cross- 

 ing the London & ISTorth Western Hallway ; from D to H, the whole 

 cutting is composed of Boulder Clay below and Drift-gravel above. 

 The Lower Lias begins to come in about H (53 miles 30 chains), 

 and it continues to thicken, at the expense of the Drift- beds, to a 

 little beyond the 54th mile (M, fig. 2, p. 70). 



With regard to the fossils, I may here say that, in order to avoid 

 needless repetition, after each description of a zone only those forms 

 will be recorded on which the identification of the zone chiefly rests ; 

 the others will be found in tabular form at the end (§ IV, p. 83). 

 Various letters are used, in that table, to indicate the relative 

 abundance of the different species. 



{a) Zone of Ammonites Turneri & A. semicostatus (fig. 1). 



About the end of May 1897 an ammonite was shown to me, at 

 the office of the Resident Engineer at Rugby, different from any 

 that I had myself found previously, and it proved to be Ammonites 

 Turneri, but the locality from which it came was not known. On 

 afterwards walking along the line I was presented with another 

 form then new to me, A. Bonnardi, and told that it came from the 

 foundations of an accommodation-bridge a little farther on, at a depth 

 of about 35 feet from the top of the cutting. Later on I found the 

 excavation, at I (fig. 1), where also were obtained numerous broken 

 specimens of A. semicostatus and A. Sauzeanus, together with other 

 Lower Lias fossils, mixed with, if not indeed actually embedded in 

 a blue Boulder Clay. In one place were large numbers of small 

 dark (phosphatic) nodules of peculiar shapes, together with others 

 lighter in colour, waterworn, and sometimes bored, also rolled frag- 

 ments of shells. At this time the cutting here had not been made 

 to its full depth, but as to the north of it only brown Boulder Clay 

 was to be found (and this was on the whole remarkably free from 

 erratics, and absolutely void of fossils, so far as I could ascertain), 

 and as to the south the nearest workable face was a very unfossi- 

 liferous Lower Lias clay, it was not easy to interpret the section 

 at I. Some six weeks later the cutting was completed sufficiently 

 to show the relation of the various beds much better, though not so 

 clearly as could have been wished, because the sloping had very 

 closelv followed upon the cutting. 



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