253 Geology and Botany of Northern Pacific Railroad. 



appearance. Douglas's spruce becomes more abundant, and the 

 trees grow larger, evidently feeling more at home, while the 

 western larch (Larix Occident alis), the western arbor \\tsd (T/iu- 

 ja gigantea], the western hemlock (Tsiiga mertensiana), and 

 Pinus monticola, never seen on the east side of the mountains, 

 multiply until they constitute the greater part of the forest. 

 The upper Columbia is the special home of the western larch 

 and the mountain pine, though they extend westward to and on 

 to the Cascade Mountains ; but about the mouth of Clark's Fork 

 they often constitute half the forest. The western hemlock be- 

 gins here with small trees, which have the aspect and indeed all 

 the characters of its eastern representative, of which it is in fact 

 only a variety. In the moist and equable climate of the lower 

 Columbia it acquires the greater size, smoother bark and more 

 fine-grained wood, which are its distinguishing characters. 



The interval between the Rocky Mountains and the Cascades is 

 quite different in its topography, geological structure and vege- 

 tation from any region east of it. It is generally destitute of 

 trees, though a few scattered yellow pines reach out from the 

 Rocky Mountains on the one side and the Cascades on the other, 

 along this line, and though not numerous grow to a large size.* 



In a general way this is a plain, but the monotony of the sur- 

 face is broken by a great number of low hills and knobs of 

 black or brown basalt, the product of the volcanic eruptions by 

 which the plain has been repeatedly flooded in Tertiary and 



* Further south this arid belt is the special home of this tree. One hun- 

 dred miles south from the Columbia Kiver, it forms continuous forests 

 where the trees, rooted in the light volcanic soil, closely set, are often four, 

 five or six feet in diameter. In these forests there is no other tree and 

 scarce any undergrowth. Here and there a clump of Cercocarpus or red 

 gooseberry is seen. The ground is usually bare, and so soft that horses 

 sink into it to the fetlocks. The absence of animal life is also striking : one 

 may travel through this forest an entire day and scarce hear the chirp of n. 

 bird or the hum of an insect ; and yet the yellow pine is there in its glory, 

 its huge, cylindrical trunk covered with large plates of cinnamon-colored 

 bark, standing as they have done for ages waiting the advent of their insa- 

 tiable enemy, the railroad man, who will some day split their trunks for 

 ties and burn their branches for fuel ; and the forests of yellow pine, like 

 those of the redwood and white pine, will be gone from the face of the 

 earth. 



