Upper Lias and Inferior Oolite in Northamptonshire. 121 



between the Kimeridgian and the Aptian of the various regions is 

 attempted. 



The comparison of the beds of England and Germany with those 

 of Russia is supported by some new evidence based on the Aucelhr, 

 four species of which are described as occurring in the Claxby 

 Ironstone and Spilsby Sandstone of Lincolnshire. 



In conclusion, the author shows that in the period under con- 

 sideration the shore-lines of Europe have been shifted by slow 

 progressive movements passing latitudinally through the region, and 

 that these movements did not affect the whole area simultaneously. 

 Hence many complicated interchanges of fauna were brought about, 

 which can only be unravelled by studying the whole course of 

 events over wide areas. 



April loth. — Dr. Henry Hicks, F.R.S., President, 

 in the Chair. 

 The following communications were read : — 

 1. ' The Junction-Beds of the Upper Lias and Inferior Oolite in 

 Northamptonshire. — Part I. Physical and Chemical.' By Beeby 

 Thompson, Esq., E.G.S., E.C.S. 



The author, while combating the view that a considerable 

 unconformity exists between the Upper Lias and the Inferior Oolite 

 of Northamptonshire, brings together much evidence to illustrate 

 the effects of slipping, and to show that these effects may be mistaken 

 for those of unconformity. He also applies the evidence which he 

 has collected to illustrate certain points in the physics of valley- 

 formation. 



After giving details as to the horizon of the springs of the district, 

 the distribution of water in the Inferior Oolite, and the development 

 of the springs, be argues that every valley of the district has been 

 elongated in the direction which it now has by a stream originating 

 in a spring always at its head, and that the development of channels 

 towards particular points of discharge has been the chief agent in 

 initiating the formation and guiding the direction of all the minor 

 valleys of the river-system within the influence of the same set of 

 beds. A description of the characters of the slopes follows, and 

 their significance is discussed. The structure of the hills and valleys 

 of the district occupies the next portion of the paper, and the 

 author considers that corresponding to the deepening of a valley by 

 denudation there is uplifting of the beds below it, and at the same 

 time an outward and upward thrust along the hillside which lifts 

 beds there ; also, that hills are reduced in height by sinking as well 

 as by denudation of their upper parts. In discussing the question 

 of unconformity between the Inferior Oolite and Upper Lias, the 

 rarity of exposures of true junctions is noted, the junctions which have 

 been chiefly examined by other observers being obscured by slipping ; 

 and reasons are given for inferring an absence of unconformity at 

 the horizon, both on account of the character of the true junctions, 

 and from other considerations. The author, however, gives reasons 



Phil. Mag. S. 5. Vol. 42. No. 254. July 1896. ' K 



