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THE RED ROCKS UNDERLYING LINCOLNSHIRE. 



HENRY PRESTON, F.G.S.. 

 Grantha?)!. 



An examination of a g^eological map of Lincolnshire reveals 

 the fact that the oldest rock masses coming- up to the surface 

 lie on the western edge of the county. There are some com- 

 paratively small patches of red Triassic strata on the east side 

 of the Trent valley just around Gainsborough and northwards 

 to Epworth and Crowle. 



The presence of these rocks in Lincolnshire is not only 

 attested by the outcrop of the red beds, but several interesting- 

 boring^s have been made which prove their existence underground, 

 and in some cases have also given their thicknesses. As to their 

 probable extension under the whole county, it should be noted 

 that in Nottinghamshire similar strata crop out rig-ht along- the 

 county, and often only a few miles away from the Lincolnshire 

 border. These rocks then dip eastwards under Lincolnshire and 

 become buried beneath newer strata. The most easterly point 

 at which they have been proved is at the boring now being put 

 down at the Lincoln Waterworks, and there is every probability 

 that they extend over the whole county, and hence may be 

 looked upon as the Great Foundation Stones of Lincolnshire. 



The Bunter rocks consist of an upper and lower bed of bright 

 red sandstone, with an intermediate bed of darker coloured 

 sandstone and pebbles. These beds cover some thousands of 

 square miles of surface, and undoubtedly form one of the most 

 important water-bearing- formations in the country. The water, 

 too, is generally of excellent quality. The Rivers Pollution 

 Commissioners describe the new Red Sandstone rock as the 

 most effective filtering- medium known, every trace of organic 

 matter being converted into innocuous mineral compounds. 



With regard to the Lincoln boring, the clays and limestones 

 of the Lower Lias have already been passed through, and at 

 the bottom of these were found the Rhaetic shales. Beneath 

 these black Rhaetic shales are red marks with bands of gypsum. 

 The boring has now penetrated these red marls to a depth 

 of 200 feet, and possibly a further 600 feet will be encountered 

 before their lower beds are reached. After the marls will come 

 beds of sandstone interspersed with numerous seams of compact 

 marl and some sands and pebble beds. Where these beds crop 

 out at the surface they throw out springs to such an extent that 



1904 October i. 



