148 CONSTRUCTION SOURCES OF GRAVEL, MINTZER 
the geological information. The ridges appeared as patterns, changes in drainage, color 
tones, erosional features and land use were found to be associated with changes in each 
pattern. Once each separate pattern was delineated, these images as a portion of the 
areal concept were kept in mind during the detailed stereo study. The stereo study of 
the landforms and the pattern elements soon revealed the area as a potential gravel 
source. Each of the potential gravel sources was delineated on the mosaic along with 
the field stations where sampling of aggregate would be taken for laboratory checking. 
  
Fig.3. An aerial reconnaissance revealed some possibilities. 
| One is seen in the oblique view: notice the light and dark 
streaks in the center of the view. 
Then several potential sites were listed on the field itinerary. About seven locations 
were sited in the study area. All sites were in either glacial lake beach ridges, morainic 
aprons, or river terraces. 
An aerial reconnaissance over the area eliminated some of the sites selected 
| previously, and those presenting real possibilities were then visited on the ground. 
While visiting and visually inspecting the potential sources, field samples were taken 
for laboratory analysis. The interpreter received an excellent idea of the pattern as 
seen from the air; see Fig. 3. To see if the gravel materials met the Ohio specifications 
laboratory tests, i.e. the Mechanical Analysis and Atterberg Limit, tests were made. 
Some of the sites were eliminated when results of the laboratory tests were made known. 
Finally, three of the original seven sites were found to contain quite suitable materials. 
The pattern of one of the best sites is outlined in Fig. 4. By close examination the 
reader should see a distinct mottled photo pattern. As it was in this case, this type of 
pattern is often a quick indication of a potential source of subbase materials. 
| Results of the study. 
Subbase sources were found within the limits of the area investigated. Two sources 
of suitable subbase materials were defined. As a result of laboratory classification tests, 
both sources were found to include suitable material meeting the specification, having