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—————— INE TEEENEN -—
REPORT OF COMMISSION VII 47
alignment in the central Atlantic coastal plain. In postulating that these fea-
tures were formed by the impact of a great swarm of meteorites, a controversy
was started which has lasted to the present time. Suffice it to say here that con-
tenders of both sides of the controversy based their views to a considerable ex-
tent on photo-interpretation (Johnson, 1942; Prouty, 1952).
In the study of sand dunes, air photography has made available for study vast
areas of desert regions extremely difficult of access on the ground, and has
thrown new light on areas already well known from the ground view. As a result,
our knowledge of dune types and varieties and their regional trends has been
greatly enlarged, and photos now available but not yet adequately studied will
make possible further extension, refinement, and perhaps revision of existing
concepts. In this subfield the work of the following deserve mention: Cooper
(1935), Madigan (1936, 1946), Melton (1940), Smith (1940), Hack (1940),
Fedorovich (1940), Tague (1947), and Capot-Ray (1948).
Shoreline geomorphology has attained a new degree of precision as a result
of air photography. Erosional and depositional forms, both subaerial and sub-
aqueous, may be studied in a degree of detail not previously feasible (Raisz,
1934; Lucke, 1934; Evans, 1940). The work of waves and currents in action
may be permanently recorded for deliberate laboratory analysis (Munk and
Traylor, 1947; Dietz, 1947; Shepard, 1950). The immediate effects of great
storms may be quickly studied (Nichols and Marston, 1939; Howard, 1939).
When the results of photo-interpretation of shoreline features have become
sufficiently extended and consolidated, they undoubtedly will lead to consider-
able revision of the once-standard treatises on this subject.
A more specialized phase of shoreline geomorphology is the study of coral
reefs. Here also the use of air photos has permitted the research worker to effect
greater speed, economy, and efficiency (Teichert and Fairbridge, 1948, 1950;
Fairbridge and Teichert, 1948).
The study of erosional and depositional phenomena of streams is a fertile
field for photo-interpretation. The principal contributors in this subfield have
been Melton (1936) and Fisk (1944, 1947). The work of the latter is of particular
significance for its effective use of photo-interpretation, together with other
methods, in unraveling the complex history of the alluvial valley of the lower
Mississippi, with particular reference to practical problems of engineering.
In the investigation of geomorphic phenomena in the permafrost areas of arctic
and subarctic regions, air photography has been of particular importance, and
the judicious combination of photo-interpretation with ground studies has led
to rapid advances in knowledge of both theoretical and practical phases of the
subject. Photo studies have permitted the selection of representative localities
for detailed examination on the ground, thus eliminating much random travers-
ing of inhospitable terrain, and have permitted extrapolation of results from
these selected localities to other areas having similar characteristics. Although
much work has been done in this field, particularly by the U. S. Geological
Survey, comparatively little has been published yet. Of historical interest are
the record of the arctic flight of the Graf Zeppelin (Weickmann, 1932) and an
earlier exploratory account by Nichols (1932). The most recent summary of
results, though with little specific mention of methods, is by Black (1951).
Other contributions dealing with various phases of the subject are by Washburn
(1947, 1950), Black and Barksdale (1949), Benninghoff (1950), Sager (1951),
and Black (1952). The latter is of particular interest for its presentation of the
most comprehensive account yet published on the polygonal ground so wide-
spread in the far north.
Other types of geomorphic features which have been studied with the aid of