314 



W. II. WEED — TWO MONTANA COAL FIELDS. 



The following section represents the strata exposed on McGriffin 

 coulee, a branch of Sand coulee, near the coal mines: 



25 Laminated hard brown sandstone. 



6 Massive coarse mottled sandstone. 



\2 Fine grained white massive sandstone. 



io Fine grained brown massive sandstone. 



id Shales, dark red, holding nodules. 



Calcareous conglomerate. 



Red shales, holding*arenaceous limestone nodules. 



Sandstone, massive, fine grained, white. 



Limestones, very arenaceous, light purple or red, with elay and calcite. 



Alternating purple and red clays and arenaceous limestone. 



Arenaceous limestone, massive, light red. 



Arenaceous limestone in purple shales. 



I 



zo Red and purple shales. 



13 Dark purple shales. 



20 Massive freestone or sandstone. 



„ Coal seam. 



i Fire-clay. 



s Gray and yellow 7 shales. 



iZ Soft ferruginous laminated sandstones. 



i'J? e Mottled gray laminated sandstones. 



t ?*v/s//y//y'/-/y\ * Stratum of impure iron ore. 



io Soft shales and clays, mostly gray. 



, Impure iron ore. 



6 Soft shales, very ferruginous. 



■3 Soft gray sandstone. 



' - * 6 Conglomerate. 



is Sandstones, massive above, laminated at base, 

 io Carboniferous (?) limestone. 



Figure 5.— Section at 

 Sandcoulee. 



The only working within this basin and the chief mine of the entire 

 field is thai of the Sandcoulee Coal company. In the prospecting of the 

 basin by this company several drill-holes were driven, which furnish 

 complete sections of the strata above the coal seam. By the kindness of 

 President ( Jocker* 1 have heen placed in possession of the records of these 

 drill-holes, sections of which are presented in the accompanying table. 

 Though sections of precisely identical strata, they differ somewhat in 

 detail and show the local changes of particular strata. The three borings, 

 designated respectively as numbers 1. 2 and 3, lie in a north-and -south 

 line at intervals of half a mile. 



*I am under obligation to him and to Superintendent Burrill for many courtesies and for 

 valuable information. 



