GEOLOGICAL SURVEY OF THE TEERITOEIES. * 449 



■svater, howeverj tlieir heating properties are not equal to those of the 

 older Carboniferous coals, while they are more liable to crumble from 

 exposure and handling. Still, when we take into consideration the great 

 scarcity of wood throughout immense areas of this internal jiart of the 

 continent, the thickness and extent of some of the beds, and their prox- 

 imity to the Pacific Eailroad, it will readily be understood that these 

 mines must be of great value. 



The main bed (division 5 of the section) must contain practically in- 

 exhaustible quantities of coal, and has a moderately firm roof of sand- 

 stone. Some difficulties, however, will be met with at places, in mining" 

 it, on account of faults and dislocations of the strata, but not greater 

 than in coal-mining in other disturbed districts. 



It is also evident that in mining these coals, great care should be 

 taken not to allow the refuse thrown from mines to accumulate at the 

 entrance, in contact with the outcrop of the coal-bed in place ,• because 

 this refuse coal, as thus exposed to the weather, is liable to take fire 

 spontaneously, and ignite the coal in the mine, causing great trouble 

 and loss, not always so much from the amount of coal consumed as from 

 filling portions of the mine with suffocating gases and smoke, as well 

 as from causing the falling in of the overlying strata. 



At Spriggs's mine, directly in Coalville, the strata, as already explained^ 

 do not conform to the general dip, and strike on the other side of Chalk 

 Creek, a little north and east of here, the strike being nearly north and 

 south, and the dip but little north of west, about 14° below the horizon. 

 The rising up of the beds here is almost co ncident with the western 

 slope from a little x^lateau of 30 to 40 feet elevation above the valley on 

 the southeast margin of the town. Formerly the mine here was worked 

 by drifts or galleries, following the coal directly from the surface under 

 the inclined sandstone, (division C,) which forms, at places, the surface 

 of the slope from the little plateau. Fire, however, was communicated 

 from the burning slack coal at the entrance of the mine, to the outcrop 

 of the coal-bed, and burned under, causing the sandstone to fall in, and 

 filling parts of the mine with smoke and gases, which were escaping 

 from cracks in the fallen-in sandstone and overlying earth when we 

 were there. 



Whether on account of inconvenience caused by the burning coal, or 

 for other reasons we did not learn, they were, when we were at the lo- 

 cality, sinking a highly inclined shaft, commencing a little above the 

 base of the slope mentioned, and cutting down obliquely through the 

 clay of division 7 and division 6, to strike coal-bed some distance below 

 the bottom of the valley. 



The dip of the strata here must cause the coal to plunge beneath the 

 valley, and, if there are no faults or fissures, to pass under Weber Eiver, 

 at a vertical depth of between 300 and 400 feet. It is therefore possible, 

 as suggested by Mr. Emmons, that there may be much trouble vath 

 water in working this bed far beneath the surface here, unless the 

 heavy bed of impervious clays (division 7) may prevent water from this 

 source from percolating down to the coal-bed. 



Th^ other mines, two to two and a half miles farther northeastward, 

 on the same bed, and at considerable higher elevations, will probably 

 be less troubled with water. Indeed, there is little reason for doubting 

 that slightly inclined tunnels might be started, at much lower horizons 

 on this bed, between the mines now worked there and Coalville, and 

 extended in a northwesterly direction, so as to drain themselves and all 

 the mines on this bed above. 



Of the mines over on Grass Creek, some four or five miles novtheast- 

 29 G s 



