ON THE FOSSILIFEKOUS THANSITION BED IN NORTHAMPIONSHIEE. 335 



By the date of delivering the report, July 25, it has not been possible 

 to thoroughly investigate all the material collected, but if anything furtlier 

 of interest is found a supplementary report will be presented in 1892. 



We particularly desire to thank Mr. S. S. Buckman, F.G.S., for 

 examining and reporting on the ammonites, and Mr. E. Wilson, F.G.S., 

 the gasteropods. 



Situation of Sections. 



The sections that have been opened are situated respectively at Milton, 

 about 3 miles S.S.W. of Northampton ; at Bugbrook, about 4 miles almost 

 due west from the last named ; near to Arbury Hill, and at Catesby, 

 about 8 miles further westward ; and at Chipping Warden, about 6^ 

 miles S.S.W. of the Arbury Hill one. 



The list of fossils contains some collected over a rather wider area 

 and extending northwards as far as Watford (on the railway), 7^ miles 

 N.E. of Catesby. 



It will be noticed, therefore, that the investigation embraces places 

 situated 14 miles apart from N.E. to S.W., and about 12 miles at right 

 angles to this. 



General Section. 



The section given below shows the sequence of the beds studied, in 

 its most complete form. 



Ft. in. 

 Unfossiliferous clays of the Upper Lias . 70 to 100 



' Communis ' f A. Upper Cephalopoda bed 6 



beds. I B. Clay with numerous small planulate ammonites 3 to 6 



Serpentinus ' J C. Lower Cephalopoda bed 6 to 9 



beds. \ D. Calcareous clay — few fossils . . . . 3 to 5 



E. Cephalopoda bed — not constant ... 04 



F. Shale — large ammonites and fish fragments . 4 



G. Fish bed— nodular 2 



H. Paper shale ....... 04 



I. Fish bed in large slabs ..... 02 



J. Paper shale 5 



Transition \ K. Red sand or sandy clay . . . . "1 1 greatest 



beds. I L. Grey marl / thickness. 



' Spinatus ' zone. M. Marlstone rock bed 6 



In regard to the above section we may say that there is no exposure 

 giving the full sequence, and that where the upper beds are shown 

 the lower ones may differ somewhat from this, and vice versa. 



With regard to B and F the evidence is about equally balanced as to 

 whether they should go with the ' Serpentinns ' beds or the Fish beds, 

 and so we prefer at present to leave it undecided. They may be I'egarded 

 as constituting a transitional zone. 



The first section was opened in the spring of 1890 at Milton, about 

 S miles S.S.W. of Northampton, but owing to the delay in procuring 

 permission, and other difBcuities experienced, that was the only one that 

 could be opened that year. In some respects, however, this was the 

 most interesting section examined. It has the advantage of being further 

 eastward than any other section exposing the same beds, and, as has 

 been pointed out elsewhere,' the beds seem to vary more at right angles 

 to the line of strike than they do along it. 



' The Middle Lias of Noi-tham^ytonshire, by Beeby Thompson, F.C.S., F.G.S. 



Fish beds. 



