Chapter 3: Geologic Structure and Landforms
Geologic interpretation of images begins with the identification of lineaments, “regional linear features caused by linear arrangement of regional morphological features such as streams, escarpments, and mountain ranges and tonal features that in many areas are the surface expressions of fractures or fault zones.”[i] The emphasis in this section is on geologic structures and landforms, both of which can be easily identified on air photographs and other images.
The sequence followed here is that often found in geomorphology books. Geologic structures and structurally controlled landforms are illustrated first, followed by images of mass wasting and of the results of the agents of erosion—running water, ground water, ice, wind and the sea. The meandering rivers of southern
3.67: Outwash Channels South of Baldur
This high-level, small-scale photo shows a series of outwash channels 1 merging into a single channel 2, today occupied by a small unnamed stream that runs into the
There is a marked contrast in land use between that on the end moraine areas and that on areas underlain by outwash. The hummocky terrain and the large number of lakes on the end moraine make arable agriculture difficult, and much of the land is tree or grass covered. The outwash areas are free of lakes and relatively flat; consequently much of the land has been cleared for agriculture, for example, between the outwash channels 8 and in the southeast. Fields in both areas are small with quarter-section sections divided into many fields 9. This contrasts with the situation in some parts of southwestern
On this small-scale photo the sections of the DLS system are very visible. Roads in the main follow section lines, for example, PTH 5 10 in the west and PR 342 11 in the east. PTH 23 12 can just be seen at the northern edge of the photo, as can the southern part of Baldur 13. The CN line is visible in the northeast 14 with a spur 15 branching off to the southwest near Greenway 16. It follows a somewhat indirect route south to
As this photo is the first in a job, details are given on the bottom left hand corner. The flight height was 24,100 feet above sea level; line 3 (photos A21852-1 to 17) was flown from west to east on August 12, 1970, as was line 8 (photos A21852-18 to 38). The camera lens had a focal length of 85.55 mm and a dark yellow filter was used.
Figure 3.67: Outwash Channels South of Baldur
Vertical air photograph: A21852-1
Flight height: 24,100 feet a.s.l.; lens focal length: 85.55 mm
Date: August 12, 1970
Scale: 1:79,200 (approx.)
Location: Townships 3 and 4; Ranges 13 and 14 WI
Map sheets: 1:250,000 62G Brandon
1:50,000 62G/6 Baldur
[i] In many cases railway lines identified on the air photos in this collection are no longer in use. However, they are mentioned because of their historical relevance to the area in which they are located.