112 I. i. RUSSELL URFACE GEOLOGY OF ALASKA. 



At Andreiefiski the river, or rather the Aphoon branch of it, is nearly 



> miles broad, and, as is usual throughout the lower Yukon, is cutting its 



jht hank. The difference between high and low water is about live feet. 



Throughout the portion of the Yukon delta that I saw, hut which must be 



:haracteristic of its entire extent, there are many abandoned channels and 



ild water-ways, some of which contain lakelets. The greater part of the 



akelets on the tundra, however, originated in other ways. See page — . 



The abandoned channel.- .-how that the stream is unstable and subject to 



many changes. This is also known from the experience of the steamboat 



captains, who have been familiar with the region for many years. 



THE HANKS OF THE tfUKON. 



Erosion oftht Right Bank. — After entering the Yukon river proper — that 

 i-. after passing the head of the first or highest branch which meanders 

 through the delta — the right bank is usually high and bold, while the left 

 bank is commonly bordered by lowlands. The fact that the Yukon through- 

 out the lower portion of its course is cutting its right bank has been men- 

 tioned by Dall and others and need not be discussed farther at this time. 



The right bank is frequently bold and rocky, and at times forms palisades, 

 all the way from the head of the delta to the Koyukuk, about twenty miles 

 above Nulato. Above that point the river Hows through broad, swampy low- 

 lands for seventy or eighty miles, and then the Lower Ramparts begin ; both 

 banks become higher ami frequently form bluffs and headlands of great 

 beauty. 



Lower L''iu>/>>irls. — In the Lower Ramparts there are high lands on each 

 side of the river. The stream is greatly reduced in width, is without islands, 

 and flows swiftly. The scenery is wild and picturesque, but scarcely more 

 impressive than the Highlands of the Hudson. 



Lowlands. — Above the Lower Ramparts for a distance of about 250 miles 

 the Yukon flows through a low. densely wooded region, which is frequently 

 Bwampy and widely overflowed during spring freshets. The river spreads 

 out into many branches, which unite and divide so a- to enclose thousands 

 of islands. 



The breadth <>t the lowlands on each side of the stream is unknown, but 

 in ascending the river the bordering highlands were frequently so distant 

 thai they could not !>• Been from the steamboat's deck. The conditions jusl 

 d< scribed extend for fully one hundred mile- up the Porcupine river. This 

 river, however, does not divide so a- to enclose islands, but forms a Bingle 



. tortuous channel where it cuts it- way through the lowlands. 



The great flatlande jusl described are of interest, as they indicate recent 

 chaugea in tie aphy of tie region. Everywhere through them there 



abandoned stream channels, showing thai probably the entire region 



