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more accurate work accomplished has become paramount, This has led to the provision of
money on estimates for their purchase and thus a more ready supply of aerial photographs
either as contact prints or as enlargements where these are necessary for the proper re-
cording of field data, Photographs are no longer regarded as too valuable to mark and in
fact for some years photographs with matte and semi-matte surfaces were specified so as to
facilitate such marking, More recently pencils of several colors which will clearly and
easily mark glossy photographs and stand up to the vagaries of weather in the field have
become available, Every Soil Survey undertaken is made with the aid of aerial photographs
which are regarded as a prerequisite,
As well as being used for formal soil mapping aerial photographs have been used
extensively for recording field studies of land-use, soil erosion and surface hydrology,
especially where these studies have been associated with soil surveys, Many features of
land use show clearly on photographs of appropriate scale, including health and vigor of
fruit trees and vines, variation in crop and pasture growth, forest plantation vigor, and
some aspects of the use of fertilizer such as the method of application of superphosphate
to pastures e.g. the rotating type of spreader leaves an irregular pattern of response
readily detected on the photographs, The various forms of water erosion and deposition
such as gully, rill, sheet and tunnel forms, wind erosion sealds and blow-outs, and drift
sand deposits are all readily identified and mapped on aerial photographs, Land-slips in
various stages also show as characteristic markings on the photographs.
In several areas, ranging from closely to sparsely settled country where soil
surveys have been undertaken, lack of cadastral surveys has resulted in an absence of the
usual base plans on which to publish soil data, In these cases base plans have been com-
piled from controlled slotted template lays of the photographs or, less accurately, by the
use of uncontrolled photo mosaics at a scale of approximately h miles to 1 inch, In the
latter case photographs of a scale of 1 in 50,000 have been used to first record the field
work which under these circumstances is always of a reconnaissance type. In a number of
cases base plans based on early land surveys have been found inaccurate or incomplete in
some portions, Aerial photographs have been used to remedy these defects,
In a number of instances vertical aerial photographs have yielded information of
direct value in pedological studies as distinct from formal soil mapping, For example in
County Victoria north of Adelaide, S.A. the erosional geretic relationship between the
clay-loam and other members of the Belalie and Canowie series was initially postulated
from the pattern and topographic positions of these soils revealed on the photographs,
(Stephens et al 1945), The prior streams theory for the origin of certain soil patterns
in the Riverine plains of N,S,W, and Victoria was clearly defined from photographs (Butler,
1950), There are numerous other cases which could be quoted,
In one particular project an attempt was made to use trimetregon photographs but
the two obliques in each set of three, while not useless, proved difficult and exasperating
to use because of their changing scale and lack of definition with distance from the fore-
ground, However a number of obliques taken as opportunity offered during airline flights
have proved useful for demonstrating pedological and geomorphic relationships of different
parts of various landscapes, It is interesting to note too that the only recorded recog-
nition of barchanoid type dunes in Australia followed observation from a civilian airliner,
So far the cost of general unavailability of vertical color photographs have pre-
cluded their use in soil survey. However, an inspection of a limited number of examples
clearly indicates that they would have considerable advantages,
REFERENCES
Butler, B,E, (1950), A theory of prior streams as a causal factor in soil occurrence in
the Riverine plains of S,E, Australia, Aust... Jd. Ag, Res, 1. 231.
Marshall, T.dJ. and Hooper, P.D. (1932). A Soil Survey of Blocks A, B, C, D, and PF, Ren-
mark Irrigation District, South Australia, ¢.8.I.R,- (Aust. ). Bull, No. 56.
Prescott, J.A. and Taylor, J,K, (1950). The Value of Aerial Photography in relation to
Soil Surveys and Classification, Jour, 6.8. 1.R. (Aust... Yo1. 3. No. h. Dp.
229-232, L plates,
Stephens, C.G., Herriott, R.I., Downes, R.G., Longford Smith T,, and Acock, A,M, (1945),
A Soil Land Use and Erosional survey of Part of County Victoria, South Australia,
G.S, T.R. (Aust, ). Bull. No. 188,
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