WORKING GROUP 3 
WEBSTER 
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defined in terms of its morphology, its position in the landscape as a whole, 
and the nature and variation of the material of which it is composed. Fig. 1 
suggests the way in which several facets occurring in the English Cotswolds 
might be defined in terms of the first two criteria. 
Others concerned with land survey have used similar units and the facet 
may be compared, for example, to the Australian land unit [Christian and 
Stewart 1952], to von Englen’s [1942] third order relief form, or, also in air 
photo interpretation, to Lueder’s [1959] unit land form. 
The Pattern 
Thus facets are basic subdivisions possessing similar soil conditions wherever 
they occur. They are definable and where their recognition has been checked 
in the field air photographs can be annotated to show their appearance. 
However, since there are likely to be several thousand facets in the world 
correct identification could prove very difficult. What is required is some larger 
unit of classification in to which facets can be organised to assist both inter 
pretation and the collation of air photographs when they have been annotated. 
Returning to Bourne we find that he observed on his sampling strips that 
certain sites were repeated again and again in association with one or several 
other sites but that sooner or later a point was reached beyond which the site 
was no longer encountered. More important, however, most or all of the 
associated sites ceased to recur from the same point, and their place was taken 
by a different assemblage of sites. This point marked the boundary between 
two distinct regions each with its own peculiar association of sites. 
Bourne’s region then is characterised by a regularly repeated pattern of a 
few, and only a few, sites or facets. Furthermore on analyses of a landscape it 
will usually be found that, except for a few outliers from adjacent landscapes, 
the facets are related to one another in the same way. All occurrences of the 
pattern may not have the same proportions of constituent facets and occasion 
ally facets may be missing from an occurrence. Nevertheless provided that the 
facets present are inter-related in the same way the pattern retains its distinctive 
character. 
Parallel to Bourne’s region is the catena concept introduced by Milne [1935] 
in order to map the soil patterns he observed in East Africa. More recently 
the soils of the whole of Uganda have been mapped using such units [Chenery 
1960] whilst several large parts of Northern Australia have been similarly 
treated using roughly equivalent land systems [Christian et ah, 1960]. 
When viewing air photographs stereoscopically one sees the land pattern 
rather than the region as a whole. It is the author’s belief that interpreters 
recognise analogues between areas largely because they exhibit similar land 
patterns which are reflected in the air photo image. Such recognition is some 
thing more than that of drainage patterns or pattern of tone, vegetation or 
land use. Lueder (loc. cit.) has illustrated the air photo appearance of some 
depositional landscape patterns but the above examples taken from Australia