A CxEOLOGIST'S PARADISE 



511 



Lower Yoho Valley the limestones of 

 Mount Ogden are lying nearly level, but 

 on the eastern slope above Sherbrooke 

 Lake Canyon the same beds are turned 

 down at right angles and disappear be- 

 neath the canyon bottom. Everywhere 

 the keen eye of the geologist will rind 

 evidence of mountain - building on a 

 grand scale. 



The panoramic photograph, taken by 

 the author from Burgess Pass, 3,000 feet 

 above Field, and published as a Supple- 

 ment to this number of the National, 

 Geographic Magazine:, shows at a 

 glance over 9,000 feet in thickness of 

 bedded rocks, 6,000 feet of it in an almost 

 sheer cliff in the mass of Mount Stephen. 

 Many thousand feet more may be seen 

 to the westward in Mount Denis and in 

 Mount Vaux. From Mount Stephen the 

 eye follows to the left across the great 

 canyon of the Kicking Horse River to 

 the summit of Mount Field, two miles 

 away, where the same limestone and 

 shale beds carrying the same fossils in- 

 dicate that thousands of feet in thickness 

 and many million cubic yards of hard 

 rock have been removed by erosion from 

 between the two mountains, Stephen and 

 Field. From Mount Field a gentle slope 

 carries the same beds northward through 

 Mount Wapta, where they undulate 

 across the President Range and plunge 

 to the westward beneath the corrugated 

 and more readily broken Ordovician 

 rocks of the Van Home Range. 



EARLY MARINE El EE 



All of the Cambrian rocks were de- 

 posited in waters teeming with marine 

 invertebrate life. As far as now known, 

 this was before the day of fish or of any 

 other vertebrate animal ; land plants and 

 even marine vegetable life were almost 

 unrepresented. Other animals of the 

 sea, however, existed in great profusion, 

 and here and there conditions were so 

 favorable for their burial in the mud and 

 sand of the Cambrian sea that they were 

 preserved unbroken, and throughout all 

 the processes of rock-making and moun- 



tain-building they have escaped destruc- 

 tion. 



In one of these favorable places the 

 most delicate of organisms, like the jelly- 

 fish, have been exquisitely preserved and 

 we have crustaceans of many varieties. 

 Among these many preserve the most 

 delicate branchiae and appendages, and 

 one can hardly realize that they were 

 buried in the mud 15 to 20 million years 

 ago and ha ye remained undisturbed 

 while several miles of thickness of sedi- 

 ment were deposited over them, changed 

 into rock, elevated into mountain masses, 

 and later eroded into the present moun- 

 tains and canyons. 



We have long considered that the trilo- 

 bite (page 516) was the most highly 

 developed animal in the Cambrian time, 

 but last summer a crustacean was found 

 by the author in the fossil bed near 

 Mount Wapta that was the king of the 

 animal world in its day (page 517). 

 That it was prepared to assert its right 

 to the control of the Cambrian sea is 

 shown by the claws with which it was 

 armed. 



To the geologist interested in the vol- 

 canic rocks a great field is waiting in the 

 Selkirks to the west, and for generations 

 to come there will be unsolved problems 

 for the special student in this great re- 

 gion of mountains, glaciers, and rivers. 



SUMMARY OE GEOLOGIC FORMATIONS 



In the long panoramic view the rocks 

 seen in the distance, forming Mount Bal- 

 four, belong to the Sherbrooke forma- 

 tion of the Cpper Cambrian, or the most 

 recent rocks of the Cambrian section. 

 Beginning with these and going down- 

 ward, the following formations arc 

 passed through : 



UPPiCR CAMBRIAN 



Feet 



Sherbrooke formation ( mainly lime- 

 stones) 1,375 



Paget formation (limestones and 



shales) 360 



Bosworth formation ( limestone and 



shale) 1,855 -f 



Total Upper Cambrian 3,590-f- 



