GEOLOGY 



The Oxford Clay and Kellaways Rock 



The Oxford Clay is now only represented by the lower beds within 

 Northamptonshire ; it forms a fringe to the east of the county, from 

 Yardley Chase to Peterborough ; patches of it occur as outliers at a few 

 places (see map) ; it underlies part of the Fenland, and probably at one 

 time covered the whole county. The formation, as here to be examined, 

 consists of a blue, slate-coloured, or brownish clay when superficial, con- 

 taining iron pyrites, selenite, septaria, and many fossils. The lowest 

 portion, a little above the Cornbrash, is shaly, and contains fissile sandy 

 layers almost passing into stone, with Avicula inaquivalvis, Gryphcea 

 bi/obata, Nucula nuda, etc., and so no doubt represents the Kellaways Clay 

 and Rock of other localities. 



The Kimeridge Clay to the Chalk 



There is some reason to believe that the Kimeridge Clay once 

 covered the county, for its characteristic fossils occur rather abundantly 

 in the Drift deposits at certain places, whereas traces of rocks of an age 

 between it and the chalk do not. It is still more certain that the county 

 was once covered with chalk, for the double reason that it could not 

 have remained above water during the deposit of the deep sea chalk 

 around, and the chalk and flint fragments of the early Drift are likely to 

 have had a home origin. 



THE SCULPTURING OF NORTHAMPTONSHIRE 



On emergence of land subsequent to the chalk period the sculptur- 

 ing of Northamptonshire began. Desiccation of the recently water- 

 logged rocks caused their exposed surfaces to crack in all directions, while 

 the gases of the atmosphere acted on them chemically. Possibly freezing 

 and thawing, but certainly wetting and drying, and heating and cooling 

 with night and day and the changes of the seasons assisted then, as they 

 do now, in breaking up the surface of the ground, while wind and running 

 water distributed the material. Assuming that denudation commenced 

 here at about the same time that Tertiary deposits were beginning to be 

 formed in the southern, south-eastern, and eastern districts of what is now 

 England, we may consider that the sculpturing of the county has 

 occupied between two and three millions of years. 



The dip of the newly-exposed ground determined the general, and 

 inequalities on its surface the specific directions of the earliest main lines 

 of drainage, but the deepening and widening of these primary valleys, 

 and the development of lateral ones, has been chiefly the work of running 

 water since. 



If we look at a map of the Catchment Basins of England, we shall 

 observe that the Wash receives water from practically every point of 

 the compass excepting that in which lies the open sea, which is at 

 least inconsistent with the general south-easterly dip of the strata we 



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