MATANUSKA AND TALKEETNA BASINS. 
105 
Matanuska River rises on the western margin of the Copper River 
plateau, flows westward and southwest ward between the Talkeetna 
Mountains and the Chugach Mountains, and enters Knik Arm at its 
eastern end. 
The Talkeetna Mountains are roughly divided into two sections by 
the drainage of Chickaloon Creek and Talkeetna River. The former 
heads in a glacier and flows southward for about 30 miles, entering the 
Matanuska about midway in its course. Talkeetna River rises on the 
northern side ol the Chickaloon Creek divide and flows northwestward 
and southwestward to Susitna River. 
The western portion of the region delimited by this division is char- 
acterized by a radial drainage, the great majority of the streams 
therein flowing away from the center of the area. In the eastern por- 
tion the drainage is divided between Matanuska and Copper rivers 
by a northwestward-trending watershed. The recent drainage has 
incised many steep-walled canyons, and progress, except along the 
larger river systems, is exceedingly difficult. 
GENERAL GEOLOGY. 
STRATIGRAPHY. 
The rocks of the area investigated display considerable variety, 
both of age and of character, ranging from highly crystalline mica 
schists of unknown age to unconsolidated Pleistocene stream and 
glacial gravels. The following section shows, provisionally, the 
stratigraphy of this area: 
Provisional statement of stratigraphy of Matanuska and Talkeetna basins. 
Age. 
Character. 
Thickness. 

Pleistocene 
Unconformity. 
Post Eocene 
Unconformity. 
Upper Eocene (Kern 
Unconformity. 
Lower Cretaceous 
Upper Jurassic and upper 
middle Jurassic. 
Unconformity. 
Lower middle Jurassic 
(?) 
Upper p ale J(Sunrise series). 
ozoic(?). 1 
(?) 
Pre-Silurian(?) 
Stream and glacial gravels 
Basaltic lavas, breccias, and tuffs t 
Coal-hearing shales, sandstones, and conglomerates. 
Limestone 
Shales, sandstones, conglomerate, tuff, and arkose. 
[(Susitna slates) 
Graywacke, shales, sandstones, and conglomerate. 
Greenstones, tuffs, agglomerates, and breccias 
Graywackes, slates, arkose, and greenstones 
Slates and graywacke slates 
Garnetiferous mica schists, albite-zoisite schists. 
Feet. 
300+ 
1,000+ 
3,000+ 
300 
2,000+ 
1,000+ 
1,000+ 
(?) 
(?) 
(?) 
The distribution of the above rocks has been indicated in a broad 
way on the accompanying map (fig. 2). On account of its small 
scale a condensation of the stratigraphic column was found neces- 
sary. An effort has been made, however, to bring out with greater 
