GEOLOGY 



and it was cut through at the northern end of Catesby tunnel on the 

 G. C. Railway. 



The Middle Lias 



A considerable change in the nature of the deposits, without any 

 striking change in the general assemblage of fossils, occurs as we pass 

 upwards into the Middle from the Lower Lias. It would appear that 

 the general depression had ceased, that the north-westerly uplift previously 

 referred to had commenced, and that it included or came near to western 

 and north-western Northamptonshire, for in these directions we find such 

 deposits in the Middle Lias as would be likely to result from the disturb- 

 ance and redistribution of the Lower Lias near at hand, such as pebble 

 beds containing rolled Lower Lias fossils {A. capricornus for instance), 

 sandstones, limestones, marls, and especially thick clay beds with a much 

 larger percentage of the quickly settling sand and mica than the Lower 

 Lias beds contain. 



It is only in the western parts of the county that the Middle Lias 

 has been and can be fully investigated, hence the abbreviated type section 

 is taken from there.' 

 TYPICAL SECTION OF THE MIDDLE LIAS OF NORTHAMPTONSHIRE 



* Water-bearing. 

 • Beeby Thompson, ' Excursion to the New Railway at Catesby, Northamptonshire,' 

 Proc. Geo/. Assoc, vol. xiv. pt. lO (Nov. 1896), pp. 65-88 ; The Middle Lias of Northamp- 

 tonshire. 



II 



