; = 
242 B. N. A. BOUNDARY COMMISSION. 
way the glaciation of the plains is accounted for, must be supposed to 
have flowed away from the Buttes, cannot have taken a direct easterly or 
westerly course, as specimens of the rock are scarce in both these directions, 
Nor does there appear to be any considerable accumulation of debris 
immediately north of the Buttes ; and a southerly course, for the drift in 
this region, would seem to be indicated. 
558. The First Branch of Milk River, where it crosses the Line, 
flows in a moderately wide valley with banks forty to fifty feet high. 
These show good sections of boulder-clay, which almost exactly resembles 
that described in the East Fork, 140 miles eastward. It is, perhaps, 
however, of a paler tint, and rather yellowish in colour. — It. includes 
glaciated stones, and shows here and there traces of stratification; and as 
before, tends on weathering to break into upright columnar fragments, 
which give the cliffs a peculiar appearance. Pale green, slaty pebbles 
were noted here in some abundance for the first time. 
559. The superficial drift examined in a favourable locality, six miles 
west of this place, gave the following percentage ratios :— 
1. ‘Quartztte Wait. SSA Pee ee ee eels ee eee 42 57 
2. Granitic and gneissic rocks, chiefly pinkish and blackish.... 22°27 
3 Slates and altered clay-rocks, pale greenish, and greyish.... 18°31 
4, Limestone, some evidently from the mountains, but the 
majority of fragments resembling that of the Red River 
coamtry | -'.\..caes ae hb eee Pe coms bal wh bn Op Ste ge Rieti oem 6°43 
5. Soft sandstone and clay-shale (local)...............s.206: 4°45 
G6, Diortte <... cio ca sao ako pda bees SiO E sys Xs et aes ae 2°47 
7. Ironstone (local)......... ge aD EE aes ye 4, db heh 1°43 
8. Fragments of Ostrea (local)...:.....00cccerenecencceens 0°99 
9, Oreptaliing -UMAres soy’. basen ee Gt aehetee a erl kee 0°99 
560. Nos. 1 and 3 are, no doubt, identical in origin, and in 
considering the derivation of the material should be treated of together. 
The most striking feature in this collection is the remarkable abundance 
of the softer rocks, which though associated with the quartzites in the 
mountains, have not previously been observed to accompany them on 
the plains in any quantity. A portion of No. 4 is also from the 
mountains, but it is almost impossible to draw distinctions in all cases 
between the limestones of eastern and northern, and those of western 
origin. They have therefore been classed together. 
561. Near the Second Branch of Milk River, the plains have an 
average elevation of somewhat over 4,000 feet, and lie about thirty 
miles from the nearest spurs of the Rocky Mountains. The drift, while 
chiefly from the mountains, contains boulders of Laurentian origin, and 
apparently also a few of the eastern white limestones. Fifteen miles 
—— a eS | 

