WORKING GROUP 9
MOLLARD
519
1. Land form. Examples: kames, eskers, outwash plains, pitted outwash
plains, glacial deltas, kame terraces, glaciofluvial terraces.
2. Expected dominant materials composing the landform. Examples: domi
nantly coarse gravelly materials, gravelly sands, chiefly graded fine to
coarse sands, “dirty” fine sands. In many cases the interpreter will preface
these terms with “expect” or “anticipate.”
3. Qualitative terms giving additional information about expected quantity
and quality of a prospect. Where the interpreter can do so, he should out
line a prospect, in heavy full line where the boundary is definite and dashed
where the boundary is indefinite or assumed. Qualitative terms frequently
used are these: shallow, deep, expect deepest portion of deposit at X, expect
deposit to be coarsest at X, deposit anticipated to be highly variable in thick
ness, very large volume of sand and gravel anticipated, small volume expected
(few 100 cubic yards), typically a “pockety” deposit, erratic stratification
pattern anticipated, depth of deposit is not predictable from airphotos, shallow
overburden is expected, prospect probably contains a detrimentally high shale
content, probably a high water table in the deposit, etc. Inferences shown on
photos, or on plans traced from them, depend largely on the occurrence and
character of landscape features the interpreter can confidently recognize in the
photos. Qualified inferences should be included if the interpreter believes they
will assist the person checking prospects in the field. If a deposit is very small
in areal extent and if it is highly doubtful that usable material exists at all,
the interpreter will often indicate a prospect by an X and, along side the X,
note simply “inspect”.
4. Finally, the interpreter will rate deposits according to relative chances of
discovering a deposit of usable quantity and quality. In the past we have
used excellent or very good to indicate the highest rating, followed by good,
fair, poor, doubtful, and “inspect”, which is the lowest rating. If in the field
the observer is near a place marked “inspect” on the photos he should check for
surface indications of sand and gravel. These relative terms, it must be pointed
out, have meaning only in terms of a particular survey objective. That is to
say, a given granular deposit may be marked “very good” in a search for high
way sub-base material but may be marked “doubtful” in a search for coarse
aggregate for use in concrete fabrication.
Common Photo-Identifying features of granular surficial deposits
The relative importance a photo interpreter assigns to a given diagnostic
feature depends to a large extent on the interpreter’s experience in that region.
In many situations only one identifying feature may appear in the photographs,
and even then it may be very weakly expressed. At the other extreme there
may be a half dozen features, all of which indicate a granular deposit. In
Western Canda the following photo-identifying features are most significant.
(See also figs. 3-8).
1. Physiographic, or geomorphic, setting.