154 ALASKAN MINERAL RESOURCES IN 1904. Lbull. 259. 
formation in which the coal beds are contained consists of sandstone, 
slate, and shale. Concerning the structure Mendenhall says: a 
The Matanuska River flows nearly along the strike of the series, although both 
strike and dip exhibit great local variations. The former is generally about N. 60° 
or 70° E., and the latter is to the northwest at various angles. * * * The beds 
are everywhere full of small faults, as though folded under slight load. 
On the basis of a few fossils found in Bubb Creek, the rocks asso- 
ciated with the coal have been tentatively referred by T. W. Stanton 
to the Lower Cretaceous, but their age has not been definitely 
determined. 
A number of creeks tributary to the Matanuska from the north are 
said to intersect the coal beds. On Moose Creek an exposure of 5 feet 
of clean coal is reported, and on Eska and Young two seams each 6 
feet thick. On King Creek a 10-foot and a 6-foot seam are said to be 
exposed. Probably the largest seams of coal are on Chickaloon Creek, 
where five beds, 5 to 35 feet thick, are reported. 
The coal ranges apparently from lignite to bituminous. It is bright 
black in color, has conchoidal fracture, but is friable and will not stand 
severe handling. It burns well in an open fire, and Jamme says that 
he made excellent coke in a miniature oven. A small specimen in 
the writer's possession is granular, having a crushed appearance, ancl 
crumbles easily. 
An analysis of an air-dried sample of coal from the Matanuska River 
field is given on page 170. 
TYONOK. 
A brown lignite of inferior quality occurs in the bluffs at Tyonok 
near the head of Cook Inlet. The inland extension of the coal-bearing 
formation is covered by gravel. Eldridge infers 6 that the Tyonok 
field extends for several miles inland and from a point 7 or 8 miles 
west of Tyonok along the coast as far northward at least as Theodore 
River. The section in the beach bluff is composed of sandstone, shale, 
and coal seams which dip southeast at angles ranging from 35° to 60°. 
The general strike of the beds, north-northeast, would carry the strata 
to a point about 10 miles up the Chulitna, where coal is reported. 
Thirty-six seams, large and small, are exposed along the beach of 
Tyonok, but it is possible that some are repetitions by faulting. They 
vary in thickness from 1 foot to 15 feet, many of them being from 4 
to 6 feet thick. Not only is the coal poor grade, but the seams are 
much broken by clay and sandstone partings. There are three or four 
seams in which one or two 3-foot benches of moderately clear coal 
might be found. 
a Op. cit., p. 308. 
*> Eldridge, G. H., A reconnaissance in the Sushitna Basin and adjacent territory, Alaska: Twen- 
tieth Ann. Rept. U. S. Geol. Survey, pt. 7, p. 21. 
