PLAIN AND VALLEY WEST OF THE PORCUPINE HILLS. 49 



height of 4,400 feet; but no more eastern drift of any kind was found 

 along the valley for 30 miles northward. If not entirely absent, it must 

 here be extremely scarce. 



At the distance just noted, near the chain of small lakes between the 

 North branch of Willow creek and the South branch of the Highwood, 

 where the wide gap of the Highwood valley begins to lay the country 

 traversed more open to the eastward, a single Laurentian boulder was 

 again seen. This was opposite the third or northernmost lake, at an 

 elevation of 4,406 feet. 



In this vicinity a well marked terrace was also found at 4,270 feet, with 

 several others faintly impressed on the hillsides up to 4,500 feet, but no 

 higher. The upward limit of terracing and of thick drift deposits ap- 

 pears here to be well defined. Large fragments of Rocky Mountain lime- 

 stone are found here and there throughout this part of the foothills gen- 

 erally stranded on prominent ridges of sandstone. 



At the head of the South branch of the Highwood, brownish earthy 

 boulder-clay, with stones wholly derived from the mountains, was seen 

 in the bank of a stream apparently resting directly on bed-rock. The 

 surface of this boulcler-clay forms a wide terrace-level in which the stream 

 valley is cut out, with an elevation of 4,240 feet, rising to about 4,290 feet 

 where it meets the slopes of the hills. In following the South branch 

 northward to a point six miles from its confluence with the main High- 

 wood, at a height of 3,960 feet, boulder-clay like the last was again seen, 

 but here holding a few very small Laurentian fragments. 



Highwood River and Vicinity. 



To the eastward of the South branch Mr McConnell made a long detour 

 among the northern ridges and plateaus of the Porcupine hills, the high- 

 est of which are there about 4,740 feet. Upon these he found abundance 

 of Rocky Mountain limestone and quartzite, but no eastern drift above 

 4,150 feet and very little drift of this origin anywhere. 



In the bank of the main Highwood, four miles above the mouth of the 

 South fork (13 miles from the base of the mountains, elevation about 

 3,700 feet), Mr McConnell examined a section showing 35 feet of boulder- 

 clay overlain by a considerable thickness of silts, and these in turn capped 

 by river gravels. The boulder-clay is dark brownish below and light yel- 

 lowish above, with stones seldom exceeding six inches in diameter, which, 

 so far as observed, are wholly of western origin. 



From the mouth of the South branch the Highwood was followed down 

 to the crossing of the railway, and midway between these points some 

 fine sections were found (see plate 1). The height of the river is here 



