KOYUKUK AND ARCTIC SLOPE PROVINCES. 45 



owing- to its feeble development to the northwest and to its remoteness from the 

 known Yukon Plateau feature, the present work, though it yields supporting- 

 evidence, has not gone far toward confirming this supposition. 



DRAINAGE. 



The drainage of this province, which is separated from that of the Arctic slope 

 by the above-described mountain range, is southwestward. The master stream is 

 the Koyukuk, which flows into the Yukon. It is navigable for some distance above 

 Settles, to near the sixty-seventh parallel. Next in size are John and Alatna rivers, 

 tributaries to the Koyukuk from the north, and South Fork from the south, all of 

 which at high water maj T be ascended by steamboat for 20 to 30 miles above their 

 mouths. Other prominent tributaries are Hokotena River or Wild Creek and Alashuk 

 River from the north and Kanuti River from the south. 



All the above streams, as shown on the map, meander over their broad, flat 

 valley floors, which vary from 1 to 10 or more miles in width. On the lower and 

 middle portion of the Koyukuk the flats attain a very much greater width, being, in 

 a measure, comparable with the Yukon Flats. To this portion the name Koyukuk 

 Flats a has been applied. 



ARCTIC SLOPE PROVINCE. 



This province, beginning at the north base of the Endicott Mountains, in latitude 

 68° 25', extends 160 miles northward to the Arctic coast. From the Anaktuvuk and 

 Colville it appears to extend eastward to the foot of the mountains, 70 to 80 miles 

 distant, while on the west it is inferred to probably extend to the Arctic coast, 

 between Point Barrow and Cape Lisburne, a distance of about 400 miles. It is mainly 

 with the eastern portion of the province that we shall here have to deal. This 

 portion embraces almost the whole of the Colville Basin, and consists primarily of 

 two distinct features, plateau and coastal plain. For the former feature the name 

 Anaktuvuk Plateau is proposed. 



ANAKTUVUK PLATEAU. 



Beginning at the north base of the Endicott Range, at an elevation of 2,500 feet, 

 as shown on the left in PI. IV, A, this gently rolling plateau or plains country, com- 

 posed of Mesozoic rocks, extends with gentle slope northward for a distance of 80 

 miles, to latitude 69° 25', where, at an elevation of 800 feet, begins the nearly flat 

 coastal plain next to be described. In the Anaktuvuk Valle}^ a still more gentle 

 aspect is given to the topography of the Mesozoic rocks by the glacial drift. 



The most prominent features of this plateau are a few low, broad ridges, which 

 lie parallel to or concentric with the curved front of the mountain range, and the 

 shallow drainage valleys (see PI. IV, A), trending north and south. These ridges 



aSchrader, F. C, Preliminary report on a reconnaissance along the Chandlar and Koyukuk rivers, Alaska, in 1899: 

 Twenty-first Ann. Rept. U. S. Geol. Survey, pt. 2, 1900, p. 468. 



