CERTAIN RIVER-VALLEYS IN LINCOLNSHIRE. 601 



pursuing what appears to be its natural course, turns southward at 

 right angles, and passing through a narrow gorge, issues into the 

 broad valley of the Steeping at Somersby. Three other tributaries 

 descend from the high ridge above described on the western side of 

 this valley ; and another from the eastern side, which, like the 

 Telford brook, looks as if it had once flowed N.E. into the Calceby 

 valley, but now turns southward through Harrington Carr into that 

 of the Steeping. 



The united waters of these brooks flow south-eastwards by Saus- 

 thorpe, Partney, and Ashby, receiving two more tributaries from 

 the north, viz. the Langton and Skendleby Becks. At Ashby near 

 Spilsby the stream turns southward, and passing between the villages 

 of Great and Little Steeping, it enters the broad plain of the Penland, 

 and is conducted by a series of dykes to the outfall near Wainfleet. 

 It is worthy of remark here that the entrance to the Steeping valley 

 between Spilsby and Partney is very narrow compared with its 

 breadth higher up and nearer its source. 



The peculiar relations of the Calceby and Steeping valleys at once 

 suggest that the first has been excavated by streams flowing east- 

 ward from the jSTeocomian hills, before the upper part of the Steeping 

 valley had its present extension ; and that these streams, which were 

 originally the head waters of the Calceby Beck, were, by the subse- 

 quent formation of the Steeping valley, intercepted and diverted 

 into that valley. 



Disposition of the Glacial Deposits. — This view of the relative 

 ages of the two valleys receives strong confirmation from the dis- 

 position of the glacial beds, and the extent to which they enter the 

 two valleys, 



The eastern flank of the Chalk Wolds is bordered by a great mass 

 of Boulder-clay, including beds of sand and gravel, and belonging 

 to the series known as the Purple and Hessle Clays. These deposits 

 are in many places from 60 to 80 feet thick, and are banked up 

 against the chalk hills, sometimes sweeping over and resting on 

 their tops. These clays and gravels enter many of the valleys 

 which open eastward, but are totally absent from others which 

 drain in the same direction, the natural inference being that the 

 Boulder-clays are posterior to the excavation of some of the valleys 

 and anterior to the erosion of the others. 



]Now the valley of the Calceby Beck is largely occupied by these 

 glacial accumulations; at its mouth between Bellean and South 

 Thoresby the ancient bed of the valley is probably 50 or 60 feet 

 below the present surface ; and the glacial beds can be traced con- 

 tinuously to the very head waters of the present stream, and far up 

 the valleys of the two tributaries which come in from the N. "W. 

 A great mass of clay and gravel blocks up the space where the 

 ancient outlets of these two tributaries into the main valley appear 

 to have been, so that the streams have been obliged to excavate 

 deep and narrow channels through the solid Chalk on either side of 

 this massive obstruction. Up the Ormsby valley Boulder-clay can 

 be traced along one side of the park, and then gives place to a wide 



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