1854.] 



TRIMMER ON SAND-PIPES. 



235 





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 ^ 



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ft^ 



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"ip 



fracture of the flints, not to movements 

 of disturbance in the chalk, which took 

 place, I conceive, during the formation 

 of the "cledge," but to the action of 

 the atmosphere during the second ter- 

 restrial or second elephantine period* ; 

 and the distribution of these fractured 

 flints, and their aggregation into heaps, 

 I refer to those aqueous operations, 

 vrhich, whatever they were, were trans- 

 ient, violent, intermittent in their action, 

 and suddenly arrested, and to which I 

 attribute the formation of the warp- 

 drift. 



In the section near the Portobello Inn, 

 between Farningham and Wrotham 

 (fig. 1), the "cledge," with its unabraded 

 flints, fills the large excavations in the 

 chalk, and the "warp-drift," with its 

 fractured flints (e, on the left of the 

 section), overlies it horizontally, and 

 may be traced thence along the northern 

 slope of the chalk, with a thickness vary- 

 ing with the elevation and form of sur- 

 face. The section near Hartley Rectory 

 (fig. 2) shows this re-arrangement of the 

 materials of the " cledge," during the 

 distribution of the warp-drift, at a point 

 intermediate between the edge of the 

 chalk-escarpment and the valley of the 

 Thames. 



The above sections are in a district 

 where the boulder-clay of the Lower 

 Erratics is wanting ; but in the sections 

 (figs. 5 & 6), which I reproduce from the 

 'Journal of the Royal Agricultural 

 Society,' vol. vii. p. 484, I exhibit cases, 

 very common throughout Norfolk, of 

 pipes and furrows in the denuded sur- 

 face of the Boulder-clay which are filled 

 with the warp-drift. 



Fig. 3. This is a section over a chalk- 

 pit at Guest, between Fakenham and 

 Foulsham. In this case two contiguous 

 sets of pipes have different infillings — 

 crag in the one, warp-drift in the other. 



Fig. 4. A section near Desborough, 

 Northamptonshire. A pipe in sand is 



* See Table, Quart. Journ. Geol. Soc. vol. ix- 

 p. 295. 



