178
SYMPOSIUM PHOTO INTERPRETATION, DELFT 1962
beschaffenheit auftraten; 3) wo eine Bodengrenze fehlerhaft kartiert worden war, u.zw. in
folge der Rundformen des Gekrieches. Die geringste Divergenz zeigte sich im Thames-
Alluvium und auf der Terrasse des Überschwemmungsgebietes. Es scheinen somit Absatz-
Landformen für die Photo-Interpretation geeigneter zu sein, als Erosionsformen. Gelände
mit Gekrieche ist infolge seiner sanften Hänge und rundlichen Formen schwierig zu bearbeiten,
u.zw. besonders in Gebieten nicht-verfestiger Sedimente. Mit der möglichen Ausnahme von
physisch deutlich gekennzeichneten Gebieten mit intensivem Landwirtschaft, ist der Masstab
1 : 10.560 für die Bodenkartierung zu gross, um aus der Photo-Interpretation Nutzen ziehen
zu können.
It has been commonly accepted that photo interpretation for soil mapping
on a large map scale, for instance 1 : 15,000 or more, is impracticable or un
economic. The object of this work was to test the practicability of photo inter
pretation as an aid to soil mapping at 1 : 10,560, carrying out first a photo
interpretation of a test area followed by a normal soil survey without reference
to the photo interpretation, and than comparing the results. Two sheets were
chosen, covering a total of 3,100 hectares (12 square miles) which together
reflect the geology, geomorphology and land use of a large part of the London
Basin. The rocks consist of Eocene clays overlying chalk: the region is much
dissected and the land forms comprise plateau and river terrace surfaces which
have been considerably affected by Pleistocene solifluction.
Two maps for each sheet area were prepared by interpretation of the air
photographs, showing respectively physiographic and relevant cultural data,
and two further maps were then constructed to show coincidence of boundaries
between these and the soil map. The map of relevant cultural data portrays
those elements of the cultural landscape which may provide clues to the soil
pattern: these include types of land use; intensity of agricultural use; par
celling - that is, the distribution of enclosures according to shape and size;
and the distribution of excavations for clay, chalk and gravel, which are often
distinguishable separately. The soil survey was carried out as part of the routine
work of the Soil Survey of England and Wales.
The area of Sheet 1 comprises relatively high land near the headwaters of
minor streams. The physiographical interpretation is presented as a map of
land forms (fig. 1). The duplicated consequent drainage pattern parallel to the
strike, and the pinnate pattern of subsequent streams, are immediately apparent.
The divisions comprise 1. broad interfluvial summits, usually cambered into a
slight convexity, 2. gully bottoms, 3a. intermediate slopes, with 3b. steeper bluffs
in places, 4. the level land of the major valley in the south east, and 5. the steep
slopes bounding this valley to the north. The cultural interpretation of Sheet 1
(fig. 2) reveals a division into predominantly arable and predominantly grass,
the former being further sub-divided into areas with large fields (with one zone
of rectangular field pattern), and areas with smaller, less regular fields. Heath
is divided according to tone, with a further minor type - heath with trees.
To what extent are soil boundaries reflected by the photo interpretation?
Fig. 3 shows the physiographical photo interpretation and soils coincidence
map for Sheet 1. Similarities between soil and slope boundaries are recognis-
