two miles in width, sunk 500 to 1,500 feet (152 to 457 m.) 

 below the present sea level. They are occasionally 

 straight, but as a rule follow a winding course, sending off 

 branches at intervals, and often opening out around rocky 

 islands. 



Two theories have been advanced to account for the 

 origin of the fiords, one that they have been excavated 

 below sea level by moving ice, the other that the coast has 

 been depressed and that they are sea filled stream valleys 

 smoothed, straightened and probably deepened to some 

 extent by glacial action. The complexity of the system, 

 the presence of midstream islands, and the northerly trend 

 of a not inconsiderable number of the fiords are difficult 

 to explain if the cutting was done entirely by ice. 



Geology. 



The Pacific Coast from Vancouver northward for 

 several hundred miles is bordered continuously by a wide 

 belt of granitoid batholithic rocks, the intrusion of which 

 commenced and reached its maximum in upper Jurassic 

 times, but continued also into Cretaceous times. These 

 rocks vary little in general character along the coast for 

 hundreds of miles. They are described in connection 

 with excursions Ci, C2 and C8. The ordinary variety 

 outcropping everywhere along the coast is a coarse, 

 greyish granodiorite, usually massive, but frequently 

 distinctly gneissic. Dark basic and light colored acid 

 varieties are not uncommon, but seldom cover large areas. 

 The roof of the long line of batholiths has been largely 

 removed by erosion, but inclusions of the rocks through 

 which they were intruded, ranging in size from small 

 fragments to areas several miles across, are seldom absent 

 in sections across the granitic belt. 



Between Vancouver and the northern end of Vancouver 

 island, the western edge of the series of batholiths follows 

 closely the mainland coast, and sedimentary and volcanic 

 rocks, referred mostly to the Triassic, outcrop in the 

 bordering islands. North of Vancouver island, the coast 

 trends more to the north, and the groups of islands fringing 

 it northward nearly to the mouth of the Skeena are all 

 granitic in character. Opposite the mouth of the Skeena, 

 a wide belt of altered sedimentary rocks, mostly quartz 

 mica schists and crystalline limestones, border the 



