213 



APPENDIX. 



NOTES ON THE MICROSCOPIC ASPECT OF THE 

 UPPER CHALK OF LINCOLNSHIRE. 



(plate XVIII.) 

 \V. HILL, F.G.S. 



No. I. — From the quarry three = quarters of a mile 

 W.S.W. of Fotherby. 



The example of the Chalk of Lincohishire on this slide will 

 compare with many examples of chalk from the base of the 

 zone of Micraster cortestudinarium from the south of Eng^land. 



Its charactei" is well marked by the large number of 

 ' Spheres ' which it contains, and, though these are not packed 

 so closely together as in some specimens of chalk from other 

 localities and horizons, yet give it an aspect which may form a 

 useful help in determining the horizon elsewhere in Lincolnshire 

 or Yorkshire. Besides these ' Spheres,' which at once take the 

 eye when the section is examined under the microscope with a 

 i-in. objective, there can be recognised foraminifera and a few 

 shelly fragments. 



Among the foraminifera Globigeriiia is the most common, 

 together with a minute Textuhirian (probably 7>.v///^//'/« minufa). 

 There are one or two other forms, but there seems neither a 

 large number nor a great variety of foraminifera in this chalk. 



Some of the shell fragments can be identified as belongings 

 to Inoceramiis, the prismatic arrangement in the shell being well 

 shown, others are too small for identification. There are also 

 three fragments of some Echinoid test, and one small Echinoid 

 spine has been cut through in making the section. 



As in many specimens of chalk, the greater part consists cf 

 amorphous calcareous matter, probably the debris of calcareous 

 organisms, which has of course surrounded and perhaps helped 

 to preserve those remains which we can still recognise embedded 

 in it. I estimate the amount of this to be about 55 per cent, of 

 the mass, the remainder largely consisting of ' Spheres,' with a 

 few foraminifera and shell frag'ments 45 per cent. 



No. 2. — From the quarry a mile west of Ulceby. 



I cannot refer to this specimen as being like the chalk of any 

 particular horizon. It consists very largely of amorphous 



1906 July I. 



■%.\ 



