110 ALASKAN MINERAL RESOURCES IN 1906. 
Last season's work extended the known area of Tertiary coal-bear- I 
ing rocks approximately 18 miles up Chickaloon Creek, though no 
outcrops of coal were observed. The discovery of an area of Mesozoic i 
rocks in the upper Matanuska Valley also extends the field in that j 
direction, as indicated on the map, though all the outcrops of coal 1 
north of Anthracite Ridge, which lies between Hicks and Boulder j 
creeks, are of a lignitic nature. 
The following paragraphs contain a brief description of the several j 
localities where coal has been observed: 
ANTHRACITE. 
Anthracite occurs along the flanks of the Talkeetna Mountains, 1 
between Boulder and Hicks creeks. It has the ordinary physical 1 
characteristics of most good coal of this kind, being heavy, firm, hard, \ 
and not much fractured. It has a high luster. The seams are not j 
much broken by small partings of shale and bone. Two sections] 
were measured by Martin. One, on the south side of Purinton Creek I 
_ _„ .^ ._,,_ 
Fig. 3. — Cross section showing relation of anthracite to intrusive diabase near Purinton Creek. 
• 
at an elevation of 3,4] feet, showed 38 feet of clean coal with both ^ 
roof and floor concealed. At this point the rocks strike N. 40° E. 
(magnetic) and dip 10° NW. into the mountain. The rocks in the 
vicinity are chiefly graywacke and sandstone and show considerable 
variation of strike and dip. A mass of diabase occupying the axis of 
an anticline which is in other places broken by a fault occurs a short 
distance below the coal. 
Martin " states that "the anthracite is probably restricted to a zone 
along the face of and in the mountains which is cut off from the valley 
plateau by a fault following the base of the mountains." 
About a mile northeast of this locality, at an elevation of 3,460 feet, 
the second section measured by Martin showed four seams of coal 
aggregating a thickness of 21 feet. The strike is N. 60° E. and the 
dip 55° SE. 
Two sections measured during the last season, farther east on the 
ridge, showed in one place 7 feet oi coal more or less mixed with shale, 
a Op. Cit., p. 18. 
