48 . REPORT OF COMMISSION VII
air photography and photo-interpretation include soil mounds (Rich, 1934;
Krinitzsky, 1949), desert desiccation cracks (Lang, 1943), lakes (Zumberge,
1952), meteor craters (Guppy and Matheson, 1950), intersecting ridges (Hor-
berg, 1951), and desert ripples (Ives, 1946).
in geomorphology are represented by the following: Smith (1941), Bobek (1941),
and Troll (1943). In summary, it may be said that the use of photo-interpretation
has given a new and revitalized approach to many fields of geomorphic study,
and will lead sooner or later to considerable rewriting of the textbooks in the
field. Research studies have been suggested and expedited by photos, a new
degree of refinement in areal studies has been made possible, regions formerly
inaccessible have been brought within the range of observation, practical ap-
plications have been facilitated, and new ideas and concepts have been stimu-
lated.
The closely related field of Pleistocene and glacial geology has benefited in a
similar way. Investigations of glacial ice and other forms of ice, with the aid of
photos, are set forth in the writings of Washburn (1935, 1941), Gould (1931,
1935), Büdel (1943), and Siple (1945). Mapping of glacial landforms on the
basis of photo-interpretation, either wholly or partly, is illustrated by the
work of Norman (1938), Wilson (1938, 1939, 1945), Sproule (1939), and Thwaites
(1943). The discovery of new types or varieties of glacial landforms is noted in
the papers of Gwynne (1942), Armstrong and Tipper (1948), and Smith (1948).
The value of photos in the study of giant ripples related to the draining of a
glacial lake is noted by Pardee (1942). Numerous other studies of Pleistocene
geology in which photo-interpretation plays a part are now in progress.
In so far as studies in geomorphology and Pleistocene geology are concerned
with depositional landforms produced by wind, running water, glaciation, and
waves and currents, their results are applicable in the field of sedimentation,
which is concerned with the mode of formation of sedimentary rocks. It is thus
evident from the preceding paragraphs that the use of photos has been signifi-
cant in this field also. Mention may be made also of a recent study by Rich
(1948), which reveals ocean bottom-features significant in the interpretation of
sedimentary rocks.
Turning now to bedrock geology, we find that here also photo-interpretation
has come to play an important part. In stratigraphy, photo-interpretation has
become an invaluable aid in tracing rock formations across country, and, under
especially favorable conditions, in recognizing variations and making sub-
divisions that are obscure on the ground. Much of this work is carried on in gen-
eral mapping projects, and the procedure is to such a degree self-evident that
comparatively little has been written specifically about it. The paper by Moore
(1947), however, does particularize.
In structural geology, the ease with which folds, faults, and fractures may be
recognized from the aerial view was early noted (Willis, 1921; Rich, 1928;
Eliel, 1929), and subsequently has been widely exploited. General aspects of
photo-interpretation in this field are discussed by van Nouhuys (1937) and
Loel (1938), and examples are described by Barton (1936), Jolliffe (1942), and
others referred to in a later paragraph concerned with areal mapping. An
unusual application of photo-interpretation to rapid reconnaissance mapping
of salient structural features on a broad regional scale is found in the work of
Wilson (1948). The role of photo-interpretation in such specialized procedures
as measuring dip and drawing structure contours is discussed in a later section
concerned with petroleum geology.
In petrology, the application of photo-interpretatior has evoked less com-
Contributions of a more general nature dealing with the use of air photos |
