Geology of Norfolk. 
475 
his strong land district. It may be divided into two sub-districts 
— those of the thick and the thin warp — though each of these, in 
point of fact, consists of many districts, separated from each other 
by soils of a different quality. 
1 . T^ie Sub-District of the deep Warp. 
A line drawn from Trimingham to Loddon, and another from 
Loddon to East Caistor, will, with a few trifling exceptions, 
include between them and the sea-coast all the best loams of East 
Norfolk, interspersed among much of a lighter and thinner staple 
and some sand, and among the peat which borders the rivers and 
broads. The areas occupied by these different varieties of soil 
are extremely irregular, the deep and strong loams being found 
in the bottoms of valleys and other low situations not covered by 
peat, the thinner and lighter loams occurring on the summits 
and upper slopes of the high ground, and the sand on steep 
escarpments, in the manner already explained. 
2. The Suh-district of the thin Warp. 
In the ti act cast of a line drawn from Trimingham to Loddon 
the better descriptions of loam prevail. In the other part of the 
eastern light land district of Smith's map there are small areas 
of the same description of soil in the valleys, but they form the 
exception, the greater portion of the district being occupied by a 
thin warp on the summits, or by the sand and gravel of the upper 
drift and crag exposed by denudation on the steep escarpments 
bounding the valleys of the principal streams. 
III. District of thk lower Drift. 
This comprises the space in southern and central Norfolk 
marked in Smith's map with the tint denoting strong land. That 
map represents, wilh as much accuracy as is possible on so small 
a scale, the area throughout which the clay of the lower drift has 
been exposed more or less by denudation. Irregular as the 
boundaries are, as shown on that map, the ramifications are 
found to be far more irregular where we follow the denudation 
into its details. This district of Smith's map is divided into two 
by the Wensum, the smallest lying to the north of that river. 
The separation is caused by the denuding action having extended 
alonof that great line of drainage through the till down to the 
sand and gravel of the crag, a large extent of which has been 
exposed on the steep sides of the valley. Within each of his 
strong land districts there is likewise every variety of soil, arising 
in some cases from denudation to a similar depth, though on a 
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