WORKING GROUP 3
PERRIN
187
Origin
It is not the purpose of this brief note to discuss the origin of the patterns,
which is to be the subject of further research. They were almost certainly formed
under periglacial conditions but, without further careful study it is not yet
legitimate to equate them with previously reported phenomena such as frost
wedges or stone stripes. If they are periglacial, they are most likely to have
formed at the end of the Gipping Advance and during the Hunstanton.
The use of air photographs in further studies
There are four main aspects of the present study of patterned ground:
1. Reconnaisance
This is directed to the discovery of new examples and of any new types of
patterns that may exist. It will be accomplished by direct observation and
oblique photography from slow-flying aircraft and by intensive search of
existing routine vertical cover.
Air photography here is an indispensable tool; as pointed out above, many
examples are too subtle for initial detection on the ground and, even if they
were, the labour of plotting every new occurrence by ground survey would be
very considerable.
2. Geographical distribution
About 150 occurrences have so far been mapped from routine vertical cover
at 1 : 10,000-1 : 20,000 scale. This has shown that the patterns are specially
characteristic of fairly shallow, light-textured brown calcareous soils or brown
earths, overlying chalk or chalky drift. Although best developed in the Breck-
land they occur also in similar circumstances on the north Norfolk coast, in
Cambridgeshire, Kent and elsewhere. Recently, air photography has shown that
patterns apparently of a very similar character exist on the Chalk in northern
France. Round the margins of Breckland where the drifts become heavy-
textured, the patterns can no longer be seen on air photographs, although similar
subsoil disturbances are sometimes seen to be present in sections.
3. Relationships with environmental factors
It is clearly of fundamental importance to relate the type and distribution
of patterns to topographic features such as slope and aspect. Although ground
checks are necessary, simple standard methods of photo-reading and photo-
grammetry afford by far the easiest approach. Preliminary work suggests that
the patterns occur on slopes facing in all directions but are best developed on
southerly slopes.
The nature and depth of the soil or substratum on which patterns are formed
can be deduced with only limited reliability from air photographs. However,
it has been found that, in very familiar areas, they can be of great value in
