164 PKOCEEDINGS OF THE GEOLOGICAL SOCIEXr. 



north, until, as shown in fig, 11 (p. 169), the trough enters the 

 body of the chalk itself near Thorpe le Mere, the Glacial clay re- 

 maining bedded up to the chalk in that part. 



The erosion of the greater part of the Subcretaceous beds, and the 

 bedding of the Glacial clay solidly against the residue of them, ac- 

 companied with an overlie of this residue by the clay at a higher 

 level than the bedded-up portion (which has led to a much greater 

 Postglacial denudation of the overlying part of the clay), is precisely 

 analogous to what we find exhibited by the Glacial clay in the case 

 where it encountered the Subcretaceous sands in Cambridgeshire, 

 and the Bagshot sands in Essex. In Cambridgeshire, along a 

 line extending from the chalk at Eversden (where it is overlain by 

 the Glacial clay, as shown in the section, fig. 7, page 402, of the 23rd 

 volume of this Journal) towards Bedford, there is the same removal 

 by the Upper Glacial sea of the greater part of the Subcretaceous 

 beds, and the bedding-up of the deposit of that sea against the unde- 

 stroyed part of those beds, as we find presented by our foregoing 

 sections (figs. 6, 7, and 8) smaU patches still remaining over the 

 undestroyed part, attesting the former overhe of this portion by the 

 Glacial clay *. Throughout central Lincolnshire, where any of the 

 Glacial clay remains, we see it resting on the shelving edge of what 

 was the Glacial sea-bottom, formed by the Prseglacial slope of the 

 Subcretaceous outcrop f. We may thus assume that it was the 

 scour of this sea, in the shallow condition obtaining at the period of 

 its first entry into the mid- Lincolnshire depression, which destroyed 

 much of the Subcretaceous series in this partj. 



The hill- ranges of Glacial clay formed by the erosion of the mid- 

 Lincolnshire valley-system, and traversed by the preceding sections, 

 are solid masses, equalling in height the chief part of the Lincoln- 

 shire Wold, being only exceeded by a small portion of it near Sten- 

 nigate. They even appear to surpass in height the northern part 

 of that Wold, where, for sixteen miles, it presents the continuous 

 scarp crossed by fig. 5 ; but the elevations not being given in the 

 Ordnance maps of this part, we have no means of knowing them pre- 

 cisely. The western heights of the Bain valley form a continuous solid, 

 range of this clay, that is in effect a continuation of the Wold-brow 

 for twelve miles from the Heneage Arms Inn to Horncastle. South 

 of that place the ridge sinks to low elevations, but is continuous to 

 Kirkby-super-Bain, the whole forming a narrow ridge nearly twenty 

 miles in length, formed throughout of the Glacial clay. The mass 

 which divides the Bain vaUey from that of the Steeping forms an 

 equally persistent range, ten miles in length, and extending from 

 near Scrivelsby to Mavis Enderby on the one side, and Wood En- 

 derby on the other § ; but, having a greater breadth than the former 

 range, it is denuded into a number of lateral valleys, through which 



* In the identical case of the Bagshot sands of Essex, see diagram sections, 

 figs. 1, 2, and 3, at page 396 of the 23rd volume of this Journal. 



t See section, fig. 11, p. 169. 



I Assisted probably by a preceding Glacier-erosion during the Lower Glacial 

 period. 



§ Fig. 7 crosses the northern, and fig. 8 the southern end of this range. 



