Arizona weekly citizen., 1882-01-01
COAL.
A Report on the Deer Greek ooal-Fieids-Iheir or,gtn and Present Condition Scientifically
 

| Report on the Doei S1eS~ S'1-- ,, origin and Present Condition scientinoAlJ Considered
 r,,,-.....u .o-,be Ene-s sec7ing and Mining Jour
 nal. hy Walter B. DeycreuS. b. M'I
 Coal was discovered in Deer Creek Valley in the early part of the present
 wear bv Anderson and Lilhe, two pros
 nactors. As soon as the discovery be-
 came known, a great deal of excitement
 onsned and in a short time tho whole
 roIlav was staked out into claims. Dur
 ;no the month of April, made brief
 y;s;t to Deer Greek, in order to aseer- 'r,rF,, possible, whether it's coal veins erecting ten stamp --hla. fuel for metal .. for twenty stamps. Inc = -
 1alh' II t''-aady completed, and all the
 would afford deslr;s- -er the ground.
 lurgical purposes, and have since De-.
 come more or less acquainted with the
 surrounding country. So many errone-
 ous statements have been published in regard to these new coal discoveries that | I propose to note briefly such observa-
 tions as have been able to make, and l the conclusions which they seem to in- | dicate. Owing to the lack of develop
 ment, only surface conditions can be de seribed, and the results of future de-
 velOpments must be considered as more
 or less prOblematieaL
 The Deer Greek cOal-felds occupy the
 eastern half of Q narrow elliptical basin, which ls surrounded .s sides by high
 ranges Of nlcan.ailis ,4h.5 basin is
 about 30 miles long and from three to five miles wide, and lies nearly east and
 west. It Is divided centrally across its
 axis by the Gila River, which has cut
 through the mountain ranges, forming a
 deep and rugged canyon. The eastern
 half of the basin is drained by Deer
 Creek, and the half west of the Gila
 River Is known as Disappointment Val
 ley. Geologically, the whole basin is
 most remarkable example of an abrupt
 synclinal valley. That portion of the
 sedimentary series which underlies 1t appears to have sunk nearly 2O00 feet | with reference to the surrounding cOun- | try. As the width of subsiding territory | was so small, the slope of the sides nec- | essarily became very abrupt; although, | at the western end, the strain was re- lieved by a series of verti cal faults, from |
 
 sedimentary series throughout this DOT ton of Arizona is exceedingly simple, | being invariably composed of a base of | quartZite, or its equivalent, and, resting | cOnformably upon the quartzite, lime | stone. The quartzite Is generally high | ly metamorphic, and its thickness is at | least several thousand feet. It has yield | ed no traces of fossils that am aware | of. The limestone Is of light gray col or, and seldom shows section over thousand feet in thickness, although where undisturbed 1t may exceed that. It contains comparatively few fossils. \ few that l obtained at Deer Creek were pronounced CarboniferOus by Dr. New berry, who kindly identified them for me.
 The third number of the sedimentary series, and one which I have so far ob- served only at Deer Creek, is brownish sandstone, friable in texture and contain ing occasional quartz pebbles It is in this sandstone that tine coal veins are found. Both appear to conform in their bedding to the underlying limestone, and consequently to the quartzite, thus bear Ing evidence that the epoch of great geological disturbance took place after the deposition of the coal
 As will be seen from what follows, cer- tain eruptiye rocks form some of the most important characteristics of thIs coal basin, and their age bears close relation to that of the coal measures It will be interesting tO note in passing that the history of these rocks Is insepar- ably connected with that of the great surface dislocatiOns of this portion of the territory, and also with that of all of our mineral veins; consequently, a care ful and critical study of this coal system will be necessary, before satisfactory in- ferences or generaliZations can be de- duced from the study of our vein sys- tems. Many valuable mineral deposits are found in the ranges which form the walls of the basin, and it Is not unlikely that others will be discovered in the basin itself
 The first discovery of coal was made | near the head of Deer Creek. The sur render this portion of the val i ley unapproachable, except over the rugged Indian trails, the one from the . San Carlos Agency, which Is about fif- ; teen miles distant, being generally fol- l lowed. The valley at this point IS about three mics broad, and 1t is here that the , great force of the subsistence Is most i clearly shown. The inner surface of the . wall is limestone, with its lines ] of stratiticatiOn nearly vertical, and in places actually reversed. Back of the ( limestone are quartzOse rocks, those on ; the north being quartZites, and those on , the sodth schistOse; their dip ill both , cases conforming to that of the lime I stone. \ short distance farther back ( from the basin, We find the quartzites i a position nearly horizontal, 1 I with their upper surfaces nearly two { thousand feet above the bed of Deer I Creek. The disiutegrati0n of the sur { country has left these quartz i ties standing Tn great masses like table t with perpendicular walls for ( hundreds of feet below their tops. From q the present appearances, 1t. seems as if the support had been removed from un- Ter the strata which overlay the area oc- ,upied now by the Deer Creek Valley, md that they had sunk down perpen- iicularly, breaking of abruptly from the [ adjoining country. Ten miles farther q town, the valley widens ont, and the ' strata on either side dip toward the cen- S Ter at an angle of about B degrees. Coal ,roppings have been discovered at inter- ( 7als down as far as the Gila River. On ,he Disappointment Valley side of the a liver, no discoveries Of coal have been a made. and, so far, l have found none of c he sandstone above described. It may, however, be concealed by the vast { mount of disintegrated material which a ills the bottom of the valley and ex- G ends mp the sides. The valley of Deer s Creek, except at the extreme eastern portion, has been greatly changed by in- I -F | appears in a large tract directly south 6 This rock consists of gray or greenish V natrix, containing large, perfectly-forIn- O d crystals of black hornblende, which I rive 1t a porphyritic appearance. The b natrix does not appear to be orthCclase, O md in the absence of the means for s making a critical examination, am in- a 'lined to consider the composition of D he whole mass as essentially dioritic, as | appears to occupy the same geological position as the diorite found abundantly trough the surrounding country. The ubsidence of the coal basin bears evi- | lence of being closely connected with S he appearance of this eruptive rock, 8 md the same relation seems to exist be- a ween the western portion of the basin il md the diorite, winch Is there found un- V by the porphyritic rock. b
 In addition, the upper end of the val s ey is intersected by two parallel dikes s f characteristic quartz porphyry, about I, hree hundred yards apart These ap- W roximate in their direction parallel fl sm to the axis of the basin, and bear D vidence of having appeared after the ' ubsIdence had ceased. The porphyry O ! almost white, and in a hard feldspar D latrix carries grains and crystals of F uartz and orthoclase. The first discov- D " of coal was made between these two Il ikes, at point about a mile from the orthern slope of the valley.
 Just on the edge of the western dike,
 second vein was discovered. These wo velns have about the same dip, " amely, 8 degrees to the south, and are d nnareuflv from siy to aigbt faat i'm l ..