58 Mr Scouler's Voyage to the Pacific Ocean 



the winter rains, and the great rise of the river during the 

 summer months, great quantities of sand are deposited in dif- 

 ferent situations. In this manner the islands of the Columbia 

 are formed, and the numerous sand banks and shoals which 

 render the navigation of this river exceedingly disagreeable. 

 Some of the islands are from two to three miles in extent, and 

 would afford the most favourable soil the Columbia possesses 

 for agricultural purposes, if this were not inundated for two 

 months every year. It is probable that all the mud and sand 

 of the Columbia is not employed in forming islands and shoals, 

 but that part of it is carried to the ocean, and by the efforts 

 of the westerly winds, is deposited to the north of Cape Dis- 

 appointment, there helping to protect the rocks from the fur- 

 ther encroachment of the sea. The nature of the rocks in the 

 vicinity of Fort George and Fort Vancouver appears to be 

 calcareous, and rocks of this character seem to prevail from 

 the cascades to the ocean. I have never been nearer than 

 sixty miles to the cascades, but from the specimens of the 

 rocks brought down by Mr Douglas, it is easy to ascertain 

 that many of them are calcareous. In addition to the calca- 

 reous rocks brought from the cascades, he also procured many 

 beautiful specimens of petrified wood, retaining their fibrous 

 texture in a very evident manner. The rocks in the vicinity 

 of Fort George were more within the sphere of my observa- 

 tion, and from that station I obtained a complete series of spe- 

 cimens. They are generally of a dark bluish colour, and in 

 some places, particularly to the north of Cape Disappoint- 

 ment, very soft, and contain many caverns. Those between 

 Tongue Point and the ocean are more hard, and consist of 

 limestone, containing many masses of a spherical form and 

 much harder consistence than the rock in which they are im- 

 bedded. They vary in size, from that of a hazel nut, to the 

 magnitude of a cannon-ball, and when broken do not exhibit 

 any traces of a crystalline structure. The quantity of fossil 

 shells was very great, although the species were not very nu- 

 merous. The shells I obtained were all bivalves. The lar- 

 gest was a species of Pecten in a good state of preservation, 

 and by no means uncommon. Two other shells were very 

 frequent, but it was difficult to ascertain to what genus they 



