The most important sources of gravel and sand in the Lethbridge area are high and low level alluvial terraces associated with the Oldman River valley. These terraces contain gravel and gravelly sand, exposed at the surface in the case of the high terraces. The low terraces commonly have up to 3 m of fine sand and silt overlying the sand and gravel. The largest of the alluvial deposits, in the vicinity of Fort MacLeod, covers approximately 40 square km and is composed of coarse gravel with a consistent thickness of 3.0 to 3.5 m.
Extensive gravel deposits of preglacial age are located in upland areas south of Fort MacLeod, south of Magrath, and in the Del Bonita area. In the vicinity of Del Bonita, 45 km south of Lethbridge, preglacial gravel covers an area of approximately 50 square km. The material varies in thickness from 3 to 5 m and generally has less than 3 m of overburden. These preglacial deposits are not being widely utilized at present but may become an important source of granular material in the future.
Good sources of coarse and medium sand are found in the same deposits within hummocky moraine zones along the Rocky Mountain Foothills, in the southwest quarter of the area.
Shetsen, I. (1980): Sand and gravel resources of the Lethbridge area; Alberta Research Council, ARC/AGS Earth Sciences Report 1981-04, 69 p.