wind has assumed the form of dunes from 10 

 to 75 feet high, either covered with bushes 

 aud a few characteristic plants, or too barren 

 to grow even sedges. 



THE UPPER VALLEY, 



West of Brandon new conditions obtain. 

 After passing the upper end of the delta of 

 Lake Agasdiz, another series of delta deposits 

 are reached near Gnswold and thence west- 

 ward, which represent a delta of the old 

 Lake Sourio into which the Upper Assini- 

 boine fell. The geology of this region is 

 rather difficult, as valleys are met with 

 through which as the levels changed the 

 waters flowed westward find afterwards east 

 ward. Suffice it to say that this delta was 

 remorselessly hollowed out and eroded by 

 the voracious Assiniboine, which in this case 

 as in that of the Lake Agassi z delta, like the 

 old Saturn cf the myths devoured its own 

 children, and now runs with rapid current 

 bordered for no less than 120 miles by the sand 

 hills originally formed by its own waters. 



THE GLACIBE THEOEl . 



It but remains to state a little more fully 

 the theory we have assumed as to the forma- 

 tion of our drift deposits. It will be noticed 

 we have postulated a vast field of land ice of 

 great depth, extending all over the north 

 of this continent, even from Labrador to the 

 Rocky mountains. It is just to state that 

 this theory is not held by all. Sir William 

 Dawson, in his "Handbook of Geology," 

 published quite recently, advances the ice- 

 berg theory by which to explain our wide 

 prairie drift deposits. He says : "There does 

 not seem to be any evidence necessitating the 

 supposition of a great northern ice cap or its 

 southward progress." He admits, however, 

 that "the glaciating agent of the Laurentian 

 plateau in the Lake of the Woods region 

 cannot have been other than glacier ice ;" and 

 further that there are difficulties yet unac- 

 counted for by the theory of tieglaciation and 

 deposit of drift on the plains by icebergs." 

 Now to all this we have to say that the thor- 

 ough measurement and examination of the 

 country by Mr Upham and other observers, 

 and the satisfactory explanation of the chief 

 phenomena seem to justify our thorough 

 acceptance of the glacier hypothesis. 



HOW ACCOMPLISHED. 



When the great ice cap extending far south 

 near tVie mouth of the Missouri began to melt 

 it receded in lobes. The mass of northern ice 

 kept a steady pressure southward. As the 

 ice receded great masses of ground up rock 

 were spread around the glacier lobes. The 

 honeycombed and broken surfaces of 

 Laurentian, Silurian and Cretaceous rocks 

 were crushed to powder, or became sand or 

 gravel ; gushing out from beneath the glacier 

 the muddy stream carried southward its load 

 and deposited it in the slack water of lakes ; 

 along the edges of the retreating ice lobe 

 vast ridges called moraines were fornned as we 

 see in any glacier in the Rockies, or Selkirks, 

 or the Alps at the present day. And these 

 formed the barriers containing lakes which 

 resulted from the melting ice. The direction 



of these great ridges with a general north to 

 south trend shows this to have been the case, 

 though there are exceptions. The great Mis- 

 souri Coteau is the terminal moraine of the 

 western glacier as it receded northward. The 

 Tiger Hills, Riding Mountains, Brandon 

 Hills, Arrow Hills and the lake are /ast 

 moraines. 



STONY MOUNTAIN. 



One of the memorials of this glacial forma- 

 tion remains to us in Ston^ Mountain north- 

 west of Winnipeg There rising 80 feet above 

 the prairie is a mass ot solid Silurian lime- 

 stone. It used to be a puzzle to us to make 

 out whether this was an enormous drift 

 boulder or was a mass of the old Silurian bed 

 in situ. Observations of late years to the east 

 on Lake of the Woods and Lake Winnipeg 

 have given us hundreds of cases of glacial 

 striee running from N. B. to S. W. showing 

 thit the course of the glacier was m that 

 direction. But to the west of Stony Moun- 

 tain the striae are seen abundantly at Stone- 

 wall and are all from N. W. to S. E. We ac 

 cordingly reason that while the tremendous 

 glacier force was ploughing out and grinding 

 up the rock surface and forming the material 

 of our fertile soil the two forces met south of 

 Stony Mountain, and left the mountain north 

 of the point of impingement, as an archaeolo 

 gical monument of the glacial era. The 

 gradual way in which the ground up material 

 was spread by lake currents over the surface 

 of the underlying rock is shown in Fig. 2, B. 

 where a. layer of boulder clay is seen covering 

 the shale of which Pembina Mt. is com- 

 posed. 



bikd's hill 

 The origin of Bird's Hill, a few miles north- 

 east of Winnipeg, was an object of considerable 

 speculation even to the old settlers. Its structure 

 hasbeen laid bare by the great excavations in it 

 made by the Canadian Paci6c and we are now 

 able to make out its origin. It consists of a 

 hill from one quarter to half a mile wide, and 

 its crest is from 805 to 810 feet above the sea. 

 The ridges of this great formation run in 

 lines of gravel and sand from northwest t > 

 southeast; the hill called by the old settlers Oak 

 Hummock to the south is a part of the sam? 

 formation, whilst the prominent eminence 

 called Moose Nose is but a continuation 

 of it. Mr. UpLam's explanation is that 

 this whole group of elevations is com- 

 posed of gravei and sand, irregularly 

 bedded (Sec. Fig. 2 B), which appear 

 to be deposits formed near the mouths of 

 glacial rivers when they flowed between walls 

 of ice and were here and there divided by ice 

 islands, When the ice about and beneath 

 melted, then the deposits sank to the bottom 

 of Lake Agassiz here about five hundred feet 

 deep Formations such as this are known to 

 geologists as "Osars." On the northern slope 

 of Bird's Hill numerous granite and gneissic 

 boulders are found, but few or none on its 

 southern slope. Osars of this kind are found 

 to the northwest of Winnipeg, ia what was 

 known to the old settlers as Grosse Isle, and 

 in that not very far from it called by the later 

 settlers Burns's Ridge. These likewise are 



