A HISTORY OF NORTHAMPTONSHIRE 



have spoken of (p. i). Again; we notice that whilst the Nene and 

 Welland rivers, and even the Ise, Harper and Willow brooks in the 

 early parts of their course, flow in a north-easterly direction, the newer 

 tributary streams of the Nene and the later-formed channels of the older 

 ones take directions much more in accordance with the present dip of 

 the strata, being even more southward than eastward (see map). All 

 this points to a second uplift of the strata not in concord with the first, 

 which, while it modified much of the drainage, could not divert the 

 then well-established main lines of the rivers. 



The Northampton Heights 



The structure and formation of hills in general will be considered 

 later, but this appears to be the proper place to speak of that range of 

 heights bordering the county to the west and north-west, from north 

 of Banbury to near Market Harborough, known as the Northampton 

 Heights or Northampton Uplands. They form an almost uninterrupted 

 fence to the county nearly approaching or exceeding 500 feet in height ; 

 patches more than 600 feet above O.D. occur about Charwelton, Cold 

 Ashby, Naseby and elsewhere, and some smaller spots reach to 700 feet or 

 more, the highest point being Arbury Hill, 735 feet. These hills consti- 

 tute a part of the diagonal water-parting of lower central England, and may 

 be regarded as a continuation of the Cotteswolds. Now considering the 

 height of the hills, the exceptional and very similar dip from all points 

 of the compass ranging between south-west through west to north to- 

 wards Northampton, confirmed by the direction of flow of the two main 

 branches of the Nene to the same place (see map), we conclude that these 

 hills represent the direction of that line of uplift which appeared to be 

 called for by differences in direction of the earlier and later-formed 

 valleys of the county. A diagonal elevation or fold, running approxi- 

 mately from south-west to north-east, on crossing the area dipping to the 

 Wash, would give rise to a curving of the Mesozoic outcrop towards the 

 depression, just as we find it. 



No evidence is available to fix the time of the probable uplift we 

 have been considering, but on the whole it is more likely to have 

 occurred during the Miocene (or early Pliocene) than any other period, a 

 time of great crust movements affecting a large portion of the earth, when 

 both the Alps and Himalayas received their last great upward thrust, and 

 when England acquired very closely the shape it now has, though it was 

 not quite severed from the continent till later. 



The Pliocene Period 



Great earth movements, by affecting the distribution of land and 

 water, would be likely to bring about changes in climate ; but whether 

 we accept this as sufficient, or add to it astronomical causes, there is clear 

 evidence that towards the close of the Tertiary — that is, in the Pliocene 

 period — the climate was getting colder, and ultimately ice reigned 

 supreme over Northamptonshire and all districts north of it. 



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