Vertical air photograph: A16405-16
Flight height: 10,500 feet a.s.l.; lens focal length: 152.63 mm
Date: October 19, 1958
Scale: 1:18,600 (approx.)
Location: Township 8; Range 14 WI
Map sheets: 1:250,000 62G Brandon
1:50,000 62G/11 Glenboro
The main requirement for sand dunes to form is a plentiful supply of sand which can be transported and subsequently deposited by the wind. In southern
The largest area of dunes in
The photograph shows a group of active dunes known as the Bald Head Hills. Bare sand is almost white on the photograph. The dune waves have a gentle upwind side (to the northwest) and a steep lee face (to the southeast). Tracing the dunes from the southeast, at least seven faces 1 can be seen with steep slopes at the angle of repose of the component sands (about 35°). On the gentle windward slopes, ripple marks can be identified especially on the first three dunes, counting from the southeast; 2 and at the back of each slope, vegetation (grasses and trees) is growing in the lowland between dunes 3. The dunes are moving slowly to the southeast in response to the prevailing northwest winds, in some cases burying trees in the process.
Another dune complex can be seen further north 4. Here there is less bare sand, although some is seen near the southeastern edge 5. The area is mainly grass-covered, but all this area was active in 1928. Also recent photographs and personal observation reveal there is much less bare sand in the southern dune complex than there was at the time of the photo.[iii] In addition to the two dune complexes, there are two dune ridges 6 both of which are now stabilized by grass and trees.
This area lies in a region where three major North American vegetation formations overlap: the Grassland (or “prairie”), the Boreal (northern coniferous) Forest, and the Temperate (eastern)
The white line in the east 13 is a path that was probably originally a fireguard but is now used for visitor access. The Bald Head Hills are now part of the
[i] Rogosin, op. cit., 1996, 56.
[ii] Rogosin, op. cit., 1996, 56.
[iii] “Of the original 6,500 square kilometers of deltaic sand, only 4 square kilometers remain open” Guide to Spruce Woods Provincial Park.
[iv] The area of open sands is also referred to as The Spirit Sands or the