226 Geological Soctety :— 
clay, (2) the red and brown clays; the former undoubtedly an ex- 
tension of the Upper or Chalky. Boulder-clay of Rutland and East 
Anglia, while the second includes the Purple and Hessle Clays of 
Mr. 8. V. Wood. These two types of Boulder-clay are very rarely 
in contact with each other, 
The brown Boulder-clays of Kast Lincolnshire rest upon a broad 
plain of Chalk, which appears to terminate westward in a concealed 
line of cliff, 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 Wyham, 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 Ferriby, 
and these clays 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 Glentham. 
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 §.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 &c., and resting 
upon blue Boulder-clay of the ‘“‘Chalky” type. Besides this sec- 
tion 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 e<in 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 these valleys. 
