RESULTS OP PREVIOUS INVESTIGATIONS. 37 



gion between the Porcupine hills and the base of the mountains, little 

 change can be made in the following statement given in the report of 



1882-'84: 



" Terraces in the entrance to the South Kootanie pass, at a height of 4,400 feet, 

 have ah-eady been described in my Boundary Commission Report (1875). In the 

 valleys of Mill and Pincher creeks, and those of the forks of the Oldman, east of 

 the actual base of the mountains, wide terraces and terrace-flats are found, stretch- 

 ing out from the ridges of the foothills, and running up the valleys of the various 

 streams. Actual gravelly beaches occasionally mark the junction of the terraces 

 with the bounding slopes, and they have no connection with the present streams, 

 which cut through them. The level varies in different localities, but the highest 

 observed as well characterized attains an elevation of about 4,200 feet. In the Bow 

 valley near Morley, and thence to the foot of the mountains, similar terraces are 

 found, which are quite independent of the modern river ; and in the wide valley of 

 the Kananaskis pass a series of terraces was seen from a distance which must rise 

 to an elevation of at least 4,500 feet." 



It is important to note that in all this region there can be no doubt as 

 to the origin of the crystalline erratics attributed to the Laurentian pla- 

 teau of the east. Neither the Cretaceous nor Laramie rocks of the plains 

 nor the Paleozoic strata of the mountains yield any such material, while 

 the eastern derivation of the granitic and gneissic drift is further evidenced 

 by its connected spread across the plains to the region of its supjDly. 

 Thus the western limit of such characteristic erratics clearly indicates 

 the extent of the drift from the Laurentian plateau. In regard to this 

 western limit, it then was observed that it practically reaches the base of 

 the Rocky mountains near the forty-ninth parallel, where Laurentian 

 boulders were found at a height of 4,200 feet. Some 30 miles to the 

 northwest and within a few miles of the mountains similar erratics were 

 found at the mill on Mill creek (3,800 feet), and one was seen near Gar- 

 nett's ranch (4,200 feet). It was added : 



" I did not, however, observe any Laurentian drift on the North fork of the Old- 

 man, and it is probable that it is absent or nearly so in the district sheltered by 

 the higher parts of the Porcupine hills. On the Bow river no Laurentian or 

 Huronian erratics were seen west of Calgary, and even after their first appearance 

 they were very scarce for some distance " (to the eastward). The elevation of the 

 Bow at Calgary is 3,393.6 feet,* and in comparing this with that of the more 

 southern localities the conclusion was drawn that " the westernlimit of the Lau- 

 rentian drift cannot conform strictly to any contour line of the present surface of 

 the country." 



The later investigations tend somewhat to modify the above state- 

 ments in showing that Laurentian drift does occur in a scanty and 



*This and some other elevations given here are derived from the results of the irrigation sur- 

 vey or from railway surveys. Most of the heights are less precise, depending on barometric ob- 

 servations reduced by comparison with Calgary. All may, however, be accepted within maximum 

 limits of error (i) of 20 feet, and are sufficiently exact for all purposes of the present paper. 



