136 Reports and Proceedings — Geological Society of London. 



Wood's papers on the Glacial beds of Yorkshire and Lincolnshire, 

 and stated as the result of his own investigations, that two distinct 

 types of Boulder-clay occur in Lincohishire, (1) the grey or blue 

 clay, (2) the red and brown clays, the former undoubtedly an ex- 

 tension of the Upper or Chalky Bouhler-clay of Rutland and East 

 Anglia, while the second includes the Purple and Hessle Clays of 

 Mr. S. V. Wood. These two types of Boulder-clay are very rarely 

 in contact with each other. 



The brown Boulder-clays of East Lincolnshire rest upon a broad 

 plain of Cbalk, which appears to terminate westward in a concealed 

 line of clifp, this cliff-line coinciding with the strike of the slope 

 which descends from the Chalk Wolds to the Boulder-clay plateau 

 by which they are bordered. The present boundary-line of the 

 Boulder-clay runs along this slope for long distances, though in 

 many places the clay has surmounted the slope and caps the hills to 

 the west of it. 



From Louth the main mass of the " brown clay " is bounded by 

 a line drawn through Wybam, Hawerby, Laceby, and Brocklesby 

 to Barrow and Barton on Humber, sweeping round the north end 

 of the Lincolnshire Wolds and occurring on both sides of the 

 Humber. Previously to the author's inspection of this district, no 

 Purple or Hessle clay had been discovered west of South FeiTiby, 

 and these cla3'S were supposed to be entirely absent on the western 

 side of the Wolds. The officers of the Survey have, however, 

 mapped several tracts of such clay in the valley of the Ancholme. 

 It occupies the surface at Horkstow, Winterton Holme, Winterton, 

 and Winteringham. It probably underlies the alluvium of the 

 Ancholme near and south of these places, and occurs again at higher 

 levels in the neighbourhood of Brigg. South of Brigg it has been 

 seen at low levels on either side of the valley of the Ancholme, as 

 far as Bishop's Bridge, near Gientham. 



Beyond this point it was not traceable in the Ancholme valley, 

 but south of Market Rasen patches of reddish-brown clay, mottled 

 with grey, and containing small flints and pebbles of chalk occur, 

 and cap the low ridges separating the valleys of the brooks. 



Another tract of Boulder-clay, which the author considers to 

 belong to the same series, occupies the western border of the Fen- 

 land, S.E. of Lincoln, what is left of it forming a ridge which runs 

 southward for many miles. It passes eastward beneath the Fen 

 deposits ; and similar mottled clay was seen in the excavations for 

 the Boston docks beneath about 20 feet of Fen-clays, etc., and resting 

 upon blue Boulder-clay of the "Chalky" type. Beside this section 

 at Boston, there are very few places where the two types of clay 

 are in contact, or so near as to afford any evidence as to their 

 relative age. Near East and West Real, and again near Louth, the 

 " Brown Clays " are banked against the slopes of hills which are 

 capped with the "Chalky Clay." The same is the case also near 

 Brigg, where the country seems to have been originally covered by a 

 sheet of the Chalky Clay, through which valleys were eroded into 

 the Jurassic clays, and the brown (Hessle) clay is found only in 



