Blue Jay, Vol.19, Issue 3

14.0 THE BLUE JAY Vol. XIX No. 3 An Odd Corner of the Province - Old Man on His Back Plateau by John H. Hudson, Saskatoon If one drives past Robsart on were the 7000-foot altitude Bearpaw Highway 13 one may see a low range Mountains of Montana, and that my of hills on the southern horizon. The distance estimate was not too far off. casual observer dismisses them as It should be added that on later visits another of our numerous stretches of I found that the East Butte of the dry morainic hills. The naturalist, Sweetgrass Hills may be spotted on however, might observe that the west the southwestern horizon. end seems to end abruptly in a sharp drop, which at the distance of Rob¬ Returning from the skyline to the sart appears as a nick in the southern immediate neighbourhood, I saw that horizon. This is abnormal for mor¬ here at its west end the plateau top is ainic hills and means some unusual almost flat, perhaps with a slight land form. One learns nothing from slope eastward. A few quartzite maps, as there is no contour map of cobblestones and glacial erratics were the area, and ordinary maps no more lying about. Save for the erratics, than name the hills “Old Man on his glacial drift was almost lacking. The Back Plateau” without more data. vegetation of the plateau was that of ordinary dry prairie, in spite of the Becoming curious about the area, altitude of over 3500 feet above sea I drove down from the Cypress Hills level. No trees were to be seen, and to the west end of the plateau in late the brush in gullies on north slopes June, 1956. A reasonable sort of earth was pretty stunted. This is dry coun¬ road brings one precisely (Fig. 1) to try south of the Cypress Hills. this west end 12.4 miles south from From the foot of the sharp drop Robsart. The south side may be view¬ the ground slopes gently awa'y for a ed by going south another three couple of miles or so till it reaches the miles, then turning east on Highway general prairie level of about 3050 46; the plateau lies to the north all feet. This outer slope is rather sad- the way east to Divide. looking country, especially to the At this west end the first thing that northwest. Seamed with shallow struck my eye was the steep rise (Fig. arroyos, and wanting in sloughs, it 2) up to the plateau top, a rise of 200- abounds in clay-shale outcrops and 300 feet above the road. This rise is burn-out pits, plain token of a short¬ covered with creeping juniper (Fig. age of glacial drift cover. 3) , from which towards the top of the Later I did run across some pub¬ slope protrudes the odd cliff of yel¬ lished information on the plateau. A lowish sandstone. When I scrambled good description and early map were up to the top, a magnificent view was given by McConnell in 1885 (1), and seen. Along the northern horizon some description and a good geologi¬ thq Cypress Hills were laid out in cal map by Furnival in 1946 (2). order from the West Block to Ravens- Their writings may be summed up crag Butte. To the southeast a squar¬ thus: The plateau is roughly oval ish tableland rose up to about eye with the long axis running about 8 level at no great distance—10 or 15 miles E.S.E. from its western tip in miles, I judged. (I later found this SE«4-10-3-25-W3rd. Glacial drift one to be Boundary Plateau). The is banked up against the north side unexpected sight was to the south. A and east end, blotting out its limits; range of jagged mountains rose about the plateau merely fades away into 1 y2 degrees above the horizon, and rolling morainic hills. (These hills are swept round in a 30° arc from 8° responsible for the origin of the east of south to 20° or 22° west of name, according to a yarn I have en¬ south. By their degree of haziness I countered somewhere but cannot guessed them about thrice the dis¬ place; their skyline as seen from the tance of the Cypress Hills, which put northwest is said to resemble the sil¬ them about sixty miles away. At that houette of a fat old man lying on his time I did not know their name or back with his knees drawn up.) Con¬ location; later I found out that these trariwise, the almost driftless west September, 1961 THE BLUE JAY 141 Views of Old Man On His Back Plateau View of west end from the north; distance View of west end from the west; distance 1V2 miles. Vl mile. Close-up of west scarp; looking E.S.E. from View from top looking north-west; shows 200 yards away. Shows juniper-covered sand¬ sandstone ledge covering plateau with, steep stone slopes. drop to barren plain beyond. end and south side stand up as a pied an interstream area in preglacial steep-sided escarpment with good time—the areas furthest from the bedrock exposures. The hard cliff¬ rivers are the last to be worn away. forming yellow sandstones (Fig. 4) The hard sandstone of the topmost of the Frenchman formation are the stratum tends to slow down erosional uppermost strata, about 60 feet thick. removal of the plateau. This old land Below lie softer strata; a few feet of surface may once have extended Whitemud white clayey sands, 18-70 quite widely south of the Cypress feet of mostly orange sands of the Hills as a lower bench, of which Eastend formation, and then grey Boundary Plateau and the bench Bearpaw shales continuing on down along the north shore of Cypress slope to prairie level and deeper. One Lake, along with our Old-Man-on- doesn’t see much of the Bearpaw on his-Back Plateau, may be remnants the slopes due to a sandy juniper- sundered by the slow erosion of covered talus, but west of the road it rivers; at any rate they all rise to outcrops on the gentle slope as light about the same elevation, 3500 feet. grey silts and clays. To the eastward along the south side of the escarp¬ REFERENCES ment, the glacial drift becomes 1. R. G. McConnell, 1885. Report on Cypress thicker, outcrops fewer, and land Hills, Wood Mountain, and adjacent country. forms more rounded. Annual Reports of the Geological Survey of Canada, part C. As to the origin of the tableland, 2. G. M. Furnival, 1946. Cypress Lake Map it is thought to be a remnant of an Area. Geological Survey of Canada .Memoir #242. old land surface like the Cypress A few further comments may be found in M. Hills, left as a hill by the removal of Y. Williams and W. S. Dyer, 1930. Geology of surrounding material. We may fur¬ Southern Alberta and Southwestern Saskat¬ chewan. Geological Survey of Canada, Memoir ther surmise that it may have occu¬ #163. .

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