150 ALASKAN MINERAL RESOURCES IN 1904. [bull. 25 
The lands in this region that are known to be eoal bearing have fc 
the most part, if not entirely, been located, and it is understood thsj 
some of the holders are about to secure patents. It seems probabl 
that there are unlocated coal lands in the unexplored area to the eas 
and northeast. 
The features to be considered by the investor and mining enginee 
embrace faults and their attendant problems, including the questio 
of local pockets; steep dips, the proportion of the seams above watt 
level, accessibility, and the physical properties of the coal as affectin 
its shipment and market value, a tendency to crush being especiall 
noticeable. 
One of the most serious of these is the question as to how much tr 
thickness appearing at the present openings may represent loc; 
expansion of the seams. This question can not be finally answere 
without extensive underground exploration. Nevertheless, there 
little doubt that the extremely great thicknesses (25 to 60 feet) repr 
sent pocket swellings and are of limited extent. Almost all sue 
great thicknesses as known in other fields occur in local pockets, ar. 
most fields with a structure like this have such pockets. But in spii 
of this there is little doubt that there are many seams which will pixn 
to be of workable thickness over large areas, and several seams whic 
will have average thicknesses of from 10 to 20 feet. The amount < 
coal, even above drainage level, is enormous. 
The shipping problems are serious, but the amount and quality < 
the coal would seem to be sufficient to justify large initial expend 
tures. It will, however, require strong companies to develop tl 
field. 
