The Alaska daily empire., 1922-01-04

GeitSIfu1uS upon tue percentages bi it's component parts. Any change in the relative proportion of these va rious parts will cause a difference in the heating value of the fuel The Matanuska Valley has suffered great physical disturbance since the coal { beds were formed, this disturbance supplying heat sufficient to drive off much of the volatile matter and mois. ture and raise the grade of the coal from Ignite to bituminous.
 When, through movements of the earth. rocks are folded so that the strata dip toward each other like the sides of the letter V. the structure is said to be a syncline; when they dip away from each other like the sides of the 1etter A,'the structure is' known as an anticline, and when a portion of the earths crust has moved relative to another portion. the plane eff slippage is known as a fault" The sides of an anticliue or syncline are called the limbs, and a line along the center of the fold, its axis
 At Eska, the beds have been folded to form a syncline, the axis of which trends east and west, the southern lfGb, where exposed, dipping about 32 degrees toward the north, and the northern limb, where exposed, dip ping from 10 to 30 degrees toward the south Six SeamA have been opened on two horizons, the upper containing the Maitland, David, and Emery beds; the lower, the Eska, Shaw and Martin. These vary in width from two and a half to five feet with az. average Of three. The beds in e2ch. series are from. 10 to 90 feet apafti and the two series are probarly separated by several hun drei feet of strata, though it is i'm. possible ;o get an accurate cross-sec 5,on on account of the faulting which .ss concealed by the overlying gravel. FaliNs were encountered on the east side, efS .Eska Creek. where the David and Dfnery beds have been dropped On the west side, several minor faults and one large one have been found. When approaching the larger fault the outcrops on the surface were mapped beyond the broken zone, their position underground plotted, and crosscut driven 600 feet through the rock to intersect them Since this time no serious faulting has been encountered
 System of Mining
 All coal produced al Eska is mined 'Jy what is known as the room and pillar" system. A tunnel, or entry. about ' by feet, is first driven on one of the coal beds with sligh; grade for drainage, and is known as
 he main haulageway or gangway. ibout 25 feet above this, and on the same bed of coal, second tunnel is driven parallel to the first, being known as the airwayi, as gall ytheg air to ventilate the minea'is taken in at this point
 The main haulaSeway is lighted by electric lights and about every 30 faft a secondary openings ocenrs eightgfece wide .and fopr4 feet. hfgh eonnecting tbes ma in. ha,tlage yiy 4o the airway Half of this opening Is occupied by a chute for coal; the ether half by q ladder. ,il TiIal. dis. tance from the main haulageway to the airway is 9 feet. and about 15 feet above the airw1y the by foot opening is wiiened out to 20 feet This is what is called room These rooms are driven every 50 feet and are 20 feet wide. which leaves a 30 foot pillar of coal between the rooms Crosscuts are driven between the rooms every 50 feet for ventilation. the average length of the room be- ing about 300 feet As the face of the room is advanced, the coal is shoveled into the chute (which is built up as the room lengthens), and drawn into the mine cars on the haulageway below. When the room has advanced 300 feet, crosscut is driven to the next room and the work of removing the pillar between the two rooms undertaken. commencing ffL Ni'V tOP F~S tiP l'iiihi ID btliOfCtt the ground behind is allowed 10 cave and that portion of the workings abandoned
 Twelve Miles of Work
 The gangway on the east stie of the mine, which opens the Shaw Eska Emery and David seams, has been driven a little over 900 feet, and on the weat side the gangway which opens the Martin. Shaw and Eska seams is something over 5000 feet in extent If all the main haul ageways, airways, rooms and cross cuts are considered, there are be tween II and 12 miles of underground work in this property.
 To ventilate the workings, short crosscut is driven through the rock to the main haulageway. and a sue tion fan Is installed. capable of pro ducing an air current of 50,000 cubic feet of air per minute. The air en- ters the mine through the airyay, is drawn up and through the rooms and back to the main .hauiageway, where 1t travels back to the fan. Doors, mar fha ont rastcn nf tho an ain haul.