200 VEGETATION OF THE PEAK DISTRICT [cH. 
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remain white; and the presence of black or white stone fences 
is a convenient indication as to whether one is in the area of 
sandstone or of limestone respectively. 
Hedgerows in the Pennine district are rare, and only occur 
where the shales are of great superficial interest, as, for example, 
near the confluence of the rivers Noe and Derwent. 
At its upper limit, the permanent pasture frequently abuts 
on the uncultivated grassland. A distinction is made on the 
Ordnance maps between “land under cultivation” and “land 
not under cultivation”; but, at and near the upper limits of 
cultivation, the boundaries shown on the Ordnance maps are 
not always reliable. A comparison of the boundary line between 
cultivated and uncultivated land as shown respectively on the 
Ordnance maps and on the accompanying vegetation maps will 
reveal rather considerable discrepancies. 
I am unaware of the principles used by the Ordnance 
surveyors in making this distinction. In the present vegeta- 
tion survey, the plan has been to make lists of the species of 
the difficult tracts, and compare the lists thus made with lists 
of tracts which are indubitably uncultivated or cultivated, as 
the case may be. There are, without doubt, many areas with 
regard to which there may be differences of opinion as to whether 
or not they should be mapped as land under cultivation; but 
this does not explain all the details of the mapping of the 
Ordnance surveyors, who, indeed, are sometimes very incon- 
sistent even on the same “six-inch” quarter-sheet. 
On the accompanying vegetation maps, the grassland not 
considered to be cultivated, although it may be more or less 
grazed, is coloured as siliceous grassland when the flora contains 
many heath-loving or humus-loving species, and coloured as 
calcareous grassland when there are many lime-loving species 
present, These two associations or groups of associations have 
been discussed in the chapter on grasslands. Some of the 
enclosed fields have apparently once been cultivated and have 
been allowed to become derelict; and such areas, by the in- 
vasion of plants from the uncultivated land, gradually approach 
in character to the neighbouring subspontaneous or spontaneous 
associations. However, up to about 1250 feet (379 m.) the 
cultivated fields may generally be kept in good condition 
without much difficulty; and one frequently sees, even at the 
