THE PRINCIPAL WORKINGS. 



319 



no expi >sures up to the summit of the table-land, 200 feet al >ove the valley 

 bottom at A.rmington ; but sections of the rocks forming the table are seen 



in small lateral drainage cuttings. 



The rocks beneath the coal are seldom exposed, as the seam is gener- 

 ally hut 50 feet or so above the creek. Where the beds are cut by the 

 railway line in the northern part of the basin the following rocks were 

 found exposed : 



Sandstone. 



ij'° Coal. 



g^ ^^ B 



oo Sandstone, alternating with shale, 



Limestone 



Sandstone, thinly bedded, alternating with 10 to L3 foot belts of 

 shale. 

 "> I>ense limestone, brown and splintery. 



Figure 8.— Section 



near Belt Ci eek. 



At Armington similar rocks are exposed near the railway bridge. 



The largest opening is the Castner mine, which was formerly worked 

 to supply the Fort Benton demand. The main entry is some (500 feet 

 loni, of which 115 feet only is timbered. In the rooms, pillars and caps 

 are used to support the roof. The seam shows a total thickness of 12 feet, 

 the uppermost 3 feet being too slaty and dirty to work and showing but 

 12 inches of coal. The bottom bench shows 20 inches of clean coal that 

 is used for blacksmithing purpose-. 



< mi the eastern side of Bell creek is the Millard claim. The section of 

 this seam is essentially the same as that of the Castner mine, as will be 

 seen by the diagram (figure 10). In the room now being worked theseam 

 shows the following section : 



» Top coal; dull and hard, with bright streakings. 



. slate, 4 inches. 



• Coal : bright, bituminous, in part a coking coal. 

 Slate, :d to I inches. 



Coal; coking, and a good forge coal. 



Slaty coal ; dirty and sulphurous, L8 inches. 

 Sandstone. 



I IG1 ii 'i Si I 



in Belt Field. 



