CERTAIN RIVER-VALLEYS IN LINCOLNSHIRE. 599 



and previously established course of a transverse stream. I now 

 proceed to describe two cases in which I believe such an inter- 

 ception has taken place. 



The Calceby and Steeping Becks in Lincolnshire. 



'Relative Position of their Valleys. — The tract of country which is 

 drained by these two streams lies at the southern extremity of the 

 Lincolnshire Wolds, which here consist of two nearly parallel ranges 

 of hills, the eastern range being that of the Chalk Wold, the 

 western consisting of Neocomian sandstones and clays capped by 

 Boulder-clay. Between these two ranges lies the broad valley of 

 the Steeping, which has been cut down through the Neocornian 

 strata into the underlying Kimmeridge Clay ; while the chalk range 

 is completely severed into two portions or masses by a deep and 

 narrow valley which gives passage to the Calceby Beck. The latter 

 is therefore a transverse valley, and the former a longitudinal one ; 

 but their relation to one another is not that which ordinarily exists 

 between transverse and longitudinal valleys. The stream in the 

 longitudinal valley is not a tributary of the other, but flows away 

 from it, and the upper part of its valley lies at a lower level than 

 the adjoining part of the transverse valley. 



The transverse valley is thus abruptly truncated and cut off from 

 receiving the brooks rising on the high ground to the westward, 

 which would naturally drain into it, but for the interposition of the 

 longitudinal valley of the Steeping. It is difficult, therefore, to 

 understand how the transverse valley could have originated, if the 

 former configuration of the district was at all similar to that which 

 it now presents. 



Both streams now rise in the neighbourhood of Tetford, a village 

 about eight miles south of Louth. The Calceby Beck has its sources 

 among the hills east of that village, the numerous springs which 

 issue from the base of the Chalk forming several small brooks which 

 unite below the small hamlet of Calceby, and thence flow north-east- 

 ward to South Thoresby. Near Calceby it also receives the water 

 of a tributary from the N.W. flowing in a longitudinal valley, which 

 has a much greater length than any of those which unite at the 

 head of the main valley. 



Another tributary comes in near South Thoresby, and springs 

 swell its volume near Belleau, where the stream emerges into the 

 broad undulating plain of Boulder-clay which intervenes between 

 the chalk hills and the marshes along the coast. Through this 

 plain the river pursues its north-easterly course in a shallow valley 

 past Claythorpe and Withern, where it passes into the marshland, 

 and is carried northward between raised banks to the sea-coast at 

 Saltfleet. 



If we now turn to trace the course of the Steeping river, we find 

 that its head waters are formed by a brook which rises near Belch- 

 ford, and flows westerly through Tetford. The valley of this brook 

 is continuous with the Ormsby valley, through which flows a 

 tributary of the Calceby Beck ; but the Tetford brook instead of 



Q.J.G.S. No. 156. ' 2u 



