204 
Psyche 
[December 
glaciation, its topography is due almost exclusively to stream 
erosion. A mantle of ‘muck’, in part decomposed organic 
material, covers the hillsides and the unconsoligated gravel 
deposits in the valleys. This mantle is in turn covered by 
varying thicknesses of moss on the hillside, which is com- 
bined with bunch grass, locally known as ‘niggerheads’ in 
the valleys. Spruce trees grow extensively on the side hill 
while clumps of birches, willows and alders are found in the 
valleys. Since the ground is permanently frozen over large 
areas and during the summer thaws to shallow depths only, 
the trees are for the most part stunted.” 
“The drainage in the area is controlled by the Tanana, the 
chief streams being the Chatanika, Goldstream, and the 
Tanana. Most of the tributaries head at about the same 
elevation, have about the same grade and carry approxi- 
mately the same amount of water. The courses of the small 
tributary streams are well defined and definite throughout 
their lengths, however, drainage conditions in the flat por- 
tion of the valleys traversed are poor, due in part to frozen 
ground and vegetation. In most of the valleys shallow 
swamps interspersed with 'niggerheads’ stand above the 
general elevation of the stream. In the broad valleys such 
as those of the Chatanika and Goldstream, large areas of 
such swamps are present. * * * 
The climate of the interior of Alaska is characterized by 
extremes in temperature and light precipitation. The so- 
called “interior” of Alaska is the drainage system of the 
Yukon River with its tributaries, the Koyukuk, Chandalar, 
Tanana, Kantishna and Porcupine Rivers. This region lies 
well to the north of the Gulf of Alaska and the Aleutian 
chain of islands. It is well known that the vicinity of The 
Alaska Peninsula is a continuous low pressure area and a 
breeding place for storms. The cyclones and anti-cyclones 
occurring in this region move eastward across the Gulf 
and follow several established routes across the United 
States and Southern Canada. The offshoots from these 
lows rarely affect the climate of the interior, although they 
