BOULDER-CLAYS OF LINCOLNSHIEE. 121 



the Witham, nothing is known of this brown Boulder-clay, because 

 it has never been looked for ; but there can be little doubt that, if 

 looked for, it would be found, because it occurs on the further side 

 of the Witham, and it is not likel}^ to be absent in the intermediate 

 area, unless it has been removed hy detrition and erosion. 



Crossing the Pens which occupy the ancient estuary of the Witham, 

 we find a strip of Boulder-clay occupying a peculiar position along 

 their south-west border. It has been already mentioned that the 

 ground occupied by the Lower Oolite south of Lincoln is entirely 

 free from Bouider-clay of any sort. The existence of this strip of 

 Boulder-clay along the Fen border was not then spoken of, because 

 there is reason to think that it belongs, not to the Chalky Clay, but 

 to the other series we have been following. 



When mapped in 1878, it was supposed to belong to the mass of 

 grey and blue Boulder-clay which comes down to the fen-level on the 

 eastern side ; the existence of Purple or Hessle Clay so far west- 

 ward was not then thought of, and the question of separating the 

 Boulder-clays had not then been raised. My note-book, however, 

 contains a mention of peculiar brown and grey mottled clay, with 

 small fragments of chalk, as seen at Martin Wood near Timberlaud. 

 I have not had an opportunity of revisiting this, but have little 

 doubt that this clay is of the East-Lincolnshire type. 



This ridge of Boulder- clay (which is capped by a remarkable 

 series of quartzitiferous gravel) passes into sheet 70 between Tim- 

 berlaud and Thorpe Tilney and becomes a promontory jutting into 

 the Fenlaud as far as BilliDghay. Its western border has, in fact, 

 been cut back by the erosive agencies which have formed the post- 

 glacial valley of the Scroby beck ; and there can be little doubt that 

 this Boulder-clay was once continuous from Walcott and Billinghay 

 to the neighbourhood of Anwick and Ewerby. 



Of the Boulder-clay of Ewerby I can speak, again, from personal 

 knowledge. By Haverholme Park it is a mottled buff and brown 

 clay, full of small chalk stones, with a gritty or sandy feel, and in 

 every respect like the clays of East Lincolnshire. At Ewerb)^ 

 Thorpe it is of a uniform dull purple-brown colour ; but this is ex- 

 csptional, and to the southward by Howell and Heckington, the 

 buif and grey tints predominate over the brown, though the mottling 

 and sandy admixture remain conspicuous features. 



Near Heckington it occupies a tract of ground which is five 

 miles wide, and it passes eastward under the silt of the Eenland. 

 The gravels associated with it and on which stand the villages of 

 HeckiDgton, Great Hale, Little Hale, and Helpringham, all contain 

 rounded pebbles of quartz and quartzite, together with flints and 

 fragments of Jurassic limestones. 



Boulder-clay of the same character continues southward by 

 Swaton and Horbling, though here the fen-beds encroach upon and 

 narrow the tract which it occupies. I have not traced it further to 

 the south than Horbling and Stow Green, and here, therefore, 

 further exploration is required with the object of acertaining its 

 -southern limit. In appearance it is so different from the grey or 



