THE GEOLOGY OF MINES AND I MINERALS.

Otago Witness, Issue 1851, 29 January 1902, Page 71

THE GEOLOGY OF MINES AND I MINERALS.

Bt Peofessok Park.

Trough Faults. — When two paiallel faults dip towards each othe_, permitting * portion of strata and coal to be thrown down between them, they form what is xpoken of a? a " trough fault.' 1 A wellknown example is -the trough fault of Dudley Port Mine, in Staffordshive, has thrown down the great 10-yard seam a d'"tance of 450 ft, as shown below: —

ordinary thickness of the coal is increased by 1 depression of the floor. Coal seams which rest close to the basement rock are always the most subject to irregularities in thickness. This is a very noticeable feature of the Auckland coalfields of Xew Zealand, where the seams conform to some extent to the contour of the basement rock. The result of this conformity is that the coal thins where the floor rises in ridges, and thickens in the hollows. Shaken coal is coal which appear* to have been completely crushed by some pressure or movement of the stiata. It is

Hitches. — These are caused by «mall and | ofte a mere heap of shapeless coal-dust, partial parallel faults, where the dMoca- wliicl is --o soft that it may be dug out tion does not exceed the tuickne=s of the with a spade. coal seam. They are veiy aptly termed B°i ding of Coal Seam R — The effect of "steps"' by coal miners. faults \ok.-ui.c ihHumou*-. or lateial pies-

Intrusive Djlcc and Their V.nc t* — Dykes consist of wall-like masses, of -gneous rock, often basaltic. They are veitictl. or inclined at various angles. ar.d often act the part of faults by displacing the strata on the opposite wall«. They sometimes run parallel to faults'. A well-known example is the Cocklk-ld dyke, which traverses the Xoiih of England coalfields. It varies from 7ft to 70ft wide, dipping north-east *t angles vaiying from. 55deg to 80deg. The walU aie bounded by 3 layei of c!a\ iiom 6111 to 12in thick. Where a dyke cros^e* ;> coal <-f-am the coal is broken up into cindery <,r b.ul todl. The injurious effects may extend to *ome distance on each *ide of the dyke Igneous intrusions and volc-an c ouibur«-t^ in coal countries may be accompanied by some adrantages. D>kes and ihea day walls often dam back water iv iniue s : and there are cases where they have enabled large tracts of coal to be woiked by damming back water in wet giound When a coal pit takes fire, the d\k". like the wall of a hou^e. H of giea/t value m arresting and confining the fire to a paiticular portion of the coalfield. Where coalfields have been intruded by great ma^es of igueou ejection's, the coal is .frequently conveited into anthiacite. When masses of coal have been entangled and enveloped in lavas, the coal ku= become changed into graphite. Mount Egmout, in New Zealand, a volcanic cone lising from sea level to 8000 ft in beautiful cuive?, is piled up on the underlying coul measures, and amoog the debris brought down by the torrents which descend from its bnow-capped peak, and furrow its sides are often found large fragments of sandstone with adhering masses of fine graphite. It is now believed that the va^t depowtof jeti oleum in tlie Baku region? were the result of the destructive distillation of the Miocene coals in the neighbourhood, caused by the volcanic outbursts of later times. Dykes cause the gieatest tioiible and loss of coal when they thiow out ramifying branches among the coal mea-uies. Cindery, or haidened, «ooty coal, produced by a dyke intru-ion, is called " dant, ' or " swad." by minets. Irregularities of Coal Seam* — The troubles met with in coal mining are chiefly '"balks, "' "nips,"' "gaws,"' '".saddle-bncks "swelbes," "put bottom^," "hoi^es and "fchaken coal." Balks are tudden thinnings in the coil. ©ccaroned Yy a depression of the roof of the seam, accompanied by a- eoiresponding depression of the floor. When the stratum above the coal invades "th* thickness of the seam, so as to almost or entirely take the place of the coal, it is called a " nip " or '" want. ' " Gaws "' and " saddle-backs " appeal- to be the reverse of nips, as the floor i« either irregular, or rises into and interferes with the continuity of the coal seam. l& " gwelUes " an 4 " pot bottoms " the

I 'me due in (lie coniinction of tl.e ciusfc of ihe c;uth lias been sometimes to bend 'die coal and in some ta--eb throw them into complicated folds, which increase the cct of working. ;md cau^f a gioat Wli'-ic of cojl hi mining. ) •» Vmuitieb 01 L'o\i.. J Ihe piinciiMl variet'es of coal recognised in 'oir.merce aie as follows: — ] Anthracite. — Haid and .-trong. with a '•hilling fracture — almost pure caibon. Steam or Smokeless L'nal — Less haid th .in Hiitbracite, which it much resembles. j Fire-burnins; C'u.-l — .Still colter; burns with ".null flame, but docs not cake togetliei : -'t 1- o known <i-> piich-coal j Caking Coil — Burns with much fl line ; ' gi\c< off much Miioke aiid cjL.es together; , \<.lual)le foi coke and gj — makmj : often ! called bituminous conl. I Ciinnel or Candle C'o^I — Bieak'. with a smooth conchoidal fractwe, and burns with a very blight flume; veiy rich 111 I iiumn C'o.il — A «;iperior ligni'e. with . e.ntliy and slialy aiipearaiice : munbles on exposure to atmo'-pheie ; seldom '•hnv <• woojy structure. LigJiite. — Ha<^ a mote in le;-s woody ai. pi'ai.mre, and i-s \ciy liirln when div. LOAL IX NEW ZEALAND. Ihe co.ili of tli.- country ure piobabh of Ko.-ene age. 1 uey coiiii«c chiefly of the varieties known as j Browu coal, containing 5 io 20 pei cent, wa'cr Pitch costl, containing 5 to 8 per cent water .Bituminous coal, containing gent^aliy le^s than 3 i>er cent, water liie brown co.ii^ predominate, and generally contain a luige propoilion of ash. They are ptmcipylly developed in the Wa:kito. Waipn and Utago coalfield*. The aveiage coinpo-ition of biown < oal is a<! follows . — Hyrt'ocaihou^ .. .. .. .. i~ j-> l ? ixc-cl caibon 3 5.2-t "Water 17 60 A-li 203 100 00 I^rxpo'jii.-c power a Ib The pij.ch coals are biuht. shiny, and fr.able. and do not c-dke. but form "■bieeze"' nlien burnt in a. retort. They include the Mokau and North Auckland coai.« The aveiage composition is a*- follow 1 - — Hvcliocarbor.s .. , 46 12 Kivl carbons .. .. 41 13 Wuter 7 45 A^-h 5 00 1 00 00 Evapcrav\ c power 30 The so-called bituminous coals en-t exclusively on the Webt Coast of the South I-land. They are valuable for steam, smithy, ga>., aad household puipo-e^. Tlie chief port of expoit is Wft>tport, follow td by Gieymouth. Turnip Seeds of the leading kinds, such as i "Standard" Swede, Rcmncy ilarcli, Sulton's All the Year Hound, Aberdeen Green, and Pidple Top Yellows, of best quality and strain, obtsuasibie icojqg i^iiuio agd B^axb, Ciuiedia.

The average composition of "We^tport and Gtermouth coals is as follows 1 — "Westport. Creymouth. Hydrocarbons.. .. 63 81 "3.25 Fixed caibon .. .. 31 S3 38. 73 .Water 3 OS 1.48 Aah 1.23 C.54 100 o,"> 100.00 Evaporative power 13.8:b :iSib In most of the Xcw r Zealand coalfields theie is only one seam of workable coal, and in mnny ploces it le^ts very close to the old flooi-rock. On the We^t Coa«t the bitiiminons coil ie«ls ou accumulations of fluviatile deposits, often of consideiable thickness. Coal Measure* — The sequence of the brown and pilch coal meaMiies is practically the 'ame throughout Xew Zealand, ard is a* follows: — - (\) Shelly limestone .. .. 40 to "!OOft tli.rk (Bi llirlv t !ay=— mari'ie .. GO to 200 ft thick (c) Soft rnariy sandstone — marine .... . 40 to CGOit thick (D* Firecl^s, gut=!, ar.d '.halea, with con! 15 to (jlit t'nck {\) The shelly limestone 1. h.nd, compact, and sub-crystalline; or meiel\ a yellow i&h-brown calcareous c tone It i^, the most distinctive horizon of the coal rocks, and -hieds or isolated patches of it aie found on ev^ry coalfield It has received mmy diffticnt names In different place, being kuow n as the Wmton, Weka Pa^b, Oaniaiu, Waipa, Waihao, Mokau, Raglan. Huntlv. Whangarei, or Waiomio limestone, all of which are local names intended to dL'«i<rnate the sime hoiizon. The mo^t cluirict°i"-iic io<---A 101111 s - me '" Pecten Hochstetlon" — ? fiat, vmootli pecten with very fine radiating <-tMffi on the outer surface of shell — and " Scalaria lylata. ' \.n) The maily clays undprlying the ]imescmiQ contain a fer. indistinct fo~M!s. piincipai.j foinmiuikri. Iv 'owe locaJitie^ they aie absent or only repic^euted by 1 few feet of ciumbling clays. (<") The soft, inaily sandstones- overlying the coal are of a greyish 01 bluMi-green colour. Thfy tjften contain a laige assemblage of maiine form«. nmoncr which tlic following aie characteristic: — Terms. Dosma, Tuiutelia, Natica, P-ecten. In pla_-e« tliej- are more clayey than arenaceous, and contain lines of lenticular calcareous concretion c , which are frequently crowded with fc-sil leuiain*. (d) The coal of New Zealand is composed of the lemoins of fein 5 . mo^es, conifeis. cycad'J, and deckluou- finest trees, the latter including the oak. elm, mynle, beech, and others. Mode of Occunence. — At the clo.*e of the Cretaceous period, Xew Zealand presented tlie appearance of a Uiuuntain throwing out branching ridges jutting into tho bej. The iesult of this configuiation was to pieient an extended and deeply•ndented coastline. Kxtensive marihy pltins foi the giowth and accumulation of co.-i vegetation did not exi^t. Vegetation could not :ici-umulatc on the steep hill side*, aid the only places where it could grow uucl>tuibed were the liver flats bordering tlie bjy.s and c-tuaiic. or on the mai'liy land-* reclaimed by laige rivei* For thi 1 * lejsou the coalfields of thi.- country c-oiiM--t of small isolated patche«-, following the contouis of the old mountain chain, rii 1 .unifying some ancient valley A rypK al station of the cojl rock*- of Xe\\ Zeilai.d I s - -*hown in the an ompanving ■■eclion —

present rank of captain. Torpedoes and gunnery are the Prince's special studies. In addition, he is a keen sportsman, and as his officers in the Implacable include some firstrate cricketers, his desire to carry off the Malta Cup next season may be gratified. — Everyone who has reason to use the Zoological department of the Natural History Division of the British Museum knows Mr Kichard Bowdlcr Sharpe, the assistant keeper of the department. About half the catalogue of birds in the British Museum i« the result of his work, and he is a special authority on certain forms of bird life. He was also the first librarian to the Zoo, an office he left to become senior as-istant in the Zoological department of tlie museum. He was 54- on November 22. — Sir Edward Groy. M.P., is one of the most attractive front bench figures of tho House of Commons. As a speaker he is agreeable and pleasant, and at times really clcquont ; if he errs at all, it is in being too shoi r. He is a distinguished sportsman, and is said "to prefer fly-fishing to political success, and would rather be successful 111 n great tennis match than in an altercation with tho present Government." Sir Edward, in 1897, proceeded to the West Indies a= a member of the Sngar Commis- = 1011 He ii only 39 years of age, and he can. if he will, become one of the leading poht'ciaus in Great Britain. — Oho point affecting tho coronation has bo-^ii settled. The Duke of Roxburghe's claim to carry the stewards' staff during the CiTPinouy lias been allowed. A young man of 25, his Grace is still, to the chagrin of multi-imllioued American heiresses, a member of tho Bachelors' Club. And this, notwithstanding a \ i*it to Newport and whole columns of the New York papers devoted to his comings and goings. Had not hi? ducal coi'ain ot Marlborougb rruccumbed at the same spot? However, the Duke was bevst man at the Majoribanks-Brodrick wedding on No\ ember 30, and such occasions afford favouraWe opportunities for Cupid to sl'oot his di»rt.«. The head of the House of K^r. who succ°eded hw father a« eighth Di'ice in 1892, after the nows of Col^nso Aoluntfercd for tlio front, and c €rved under Lord .Roberts till after the fall of Pretoria. S<r,ce then ho has gained much valuable experience as one of the staff of%the Prince of Wales during the tour of tho Opbir. For nohtioa he has not shown much inclination, but there is plenty of time for that yet. — Dr Temple was 80 year* old on Xovpiubpr 30 E\er a fighter, the Pnmato by his absolute ho'iie^ty and fcrco af character has won the respect of those who differ from him ou almost every point of church policy. Tlie day has indeed long gone by when the archbisiiop was legarded as heretical, and denounced 111 unmeasured terms by the militant Low Churchmen. If his t-cholar-sh.p is not profound, ho is po<s=e=socl of a genius for administrative work which no member of tlie bench of bishops can hope to u' al. I]i foot, hi-) is the commanding figura 111 the church, and its fittest representative. It is 54- years «mc& his ordination : 32 years «ince he ceased to be the "jupt bea^t" who ruled Rugby : 16 years since be was tiansferrcd from Exotcr to London : and five ycar<> t-ince he became Primate of All England. Ail ad\ aiaced temperance reformer, he had ncveclJieless .Uirued 50 before he became a teetotaller. Thero arc but two bishops senior to his Gtscc — the ■» Pnerable Dr Kllicott, now in hi- eighty-third year, and the Bishop of LlandafF, who was SO la. c t . March. i — The Jtight Hon. Mr Balfour. who !:2S lately iccovor»d from a severe attack of i>ifluenza, could hardly have cho^ri a better house in which to fall ill than Taplow Cnurr. Maidenltead. and ee-rtairJy it would be difficult to find boat and hostess who would bp more kind and attentive to any c ick guest than Mr and Mrs W. H. Grenfell. Mr Grenfcll i^ a man of whom athletic Eneland is • proud. A double Blue (he> represented Oxfoid in rowing and athlotics), he has twice Xiagara, and is still Leenly interested in all matteis pertaining to oarsmanship. Tlif Daik Blue crew are often his guests during part of their training, and no man is tnorp familiar at Heniey than Mr Grenfell. He has decided viewis on the question of foreign on fries, and The Times accords hi* letters on tiic subject "" leader " type. At odd timo^ he lias acted as war correspondent, and has boon in and out of Parliament »ince 18S0. He created a mild sensation by resigning his seat for Hereford in 1892, because he could not sunport Mr Gladstone's Home Rnlo Bill. Mrs Gronfcll is a daughter of tl.p Tion. Julian Fane, and was married in 1537.

1 L.iiiL-tor-e. .| nicJ.m, »t,t nv a co?[. J Marly and an>ii]3 > c'ava. ",. Cascihcut ruck. J Soft muily <=andstonc.-, or ?o"t b'ovn b.\i.i'