blackfoot-valley

west side of the valley on Ranch land, easily identified by their smooth slopes and mostly treeless, grassy cover. (They’re not true foothills, of course, hav- ing been deposited long after the basic slopes were formed and by a wholly different agency.) Moraines range in height from a few dozen feet or less to a few hundred feet. The lateral moraines, such as just described, represent one of the most common types. The common type in this valley, smaller but more numer- ous, are the terminal moraines, which were deposited at the ends of glaciers. Since the rocks they carry can be taken no farther, they pile up there as long as the glacier foot remains at that spot. If the rate of the glacier’s flow more or less equals the rate of melt at its foot for some time, it may build up a size- able hill of such rubble. If, say, it then retreats a bit, its foot may pause in a new position long enough to build up another such pile, and so on. These are often called recessional moraines to make the process more clear, though they are really just special cases of terminal moraines. Terminal / recessional moraines such as these pepper much of the Ne- vada / Blackfoot Valley north and west from the vicinity of Helmville. If you are driving from Helmville to the Ranch headquarters, you cross a small mo- raine, a low rise that gives you your first view of the Ranch buildings. More are found in the Ranch’s northern sector (the Wales Ranch), the largest one being a prominent pair of hills connected by a saddle, seen to your right as you drive northbound on Wales Creek Road. They rise 100 to 200 feet higher than the road and about 300 feet above Blackfoot River on the other side. (The summit of the higher hill is crossed by a trunk power line.) Where the road passes by the nearer hill you can see the gouge of the activity used to quarry for rocks and gravel. Moraines are often convenient sources for these, being built of rocks ranging from sand to boulders, concentrated and often well differentiated as to size, with no more than a thin soil cover. On the other side of the Blackfoot, mostly north of the Ranch land, a jumble of “bumps,” dot the landscape, rising haphazardly from alluvium more recently deposited by stream action, with the hollows between filled by ponds. The Helmville-Ovando county road passes through the heart of this area. Meriwether Lewis, returning east with a small party temporarily sepa- rated from William Clark’s party in the summer of 1806, passed through the locality and called it, in his casual spelling, “the prarie of the knobs.” Ovando is nestled among a group of higher morainal hills or “knobs” that dominate the town’s immediate surroundings and extend some miles south. 28