520 
SYMPOSIUM PHOTO INTERPRETATION, DELFT 1962 
Fig. 5. Several tens of millions of cubic yards of granular construction materials were required 
to build a major earthfill dam at centerline X-X. Large volumes of pervious earthfill as well 
as concrete aggregates were needed. A number of photo-identifying features are shown in 
this photo: “gravel-type” gullies in deep coarse gravels A, C and E; gullies in deep stratified 
sands to fine gravelly sands at B, D and F; faint current scars at H; a kettlehole at G. These 
features occur on a series of channeled deltas that were built into a glacial lake at different 
elevations of the lake surface. Letter D is located on the frontal slope of one such delta. The 
inflowing river to the glacial lake came from the upper part of the photo. Thus the interpreter 
may expect to find a gradual coarsing of granular strata toward the apex of individual deltas 
(i.etoward the top of the photo). 
2. Slope details, such as relative steepness of slopes and intersection angle 
between contiguous slopes. 
3. “Fossil - ” current markings and old channel scars- often largely obliterated 
by longtime weathering and erosion, unless the deposit is quite coarse in 
texture. 
4. Kettleholes in glaciofluvial materials (kettleholes in glaciofluvial sediments, 
incidentally, appear quite different from kettleholes in glacial till deposits). 
5. “Gravel” gullies. The length-breadth ratio, location, density, cross-sectional 
shape and physiographic setting of gullies are all significant. 
6. Details of microrelief. Tapioca-like appearance is one of several diagnostic 
tonal patterns. The pattern of small dark depressions reflects higher mois 
ture contents, higher organic contents and, generally speaking, deeper and 
heavier-textured surface horizons. 
7. Tonal pattern and relation of soil tones to microrelief features. 
8. Land use. Existing pits. Also granular subsoils have low moisture-retention