The Mining Magazine, Vol. 45, No. 2

The Mining Magazine

M anaging Director and E d ito r : W . F . W h i t e . A ssista n ts : S t . J . R . C. S h e p h e r d , A .R .S .M .,D .I.C ., F.G .S.;

F . H i g h a m , A .R .S.M ., M .Sc., F.G .S.

P u b l i s h e d o n t h e 1 5 t h o f e a c h m o n t h b y M i n i n g P u b l i c a t i o n s , L i m i t e d , a t S a l i s b u r y H o u s e , L o n d o n , E .C . 2 .

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Vol. X L V . No. 2. L O N D O N , A U G U S T , 1931

C O N T E N T S

PAGE PAGE

E d i t o r i a l T o r o n t o ... 99

N o t C S 6 6 Porcupine; Kirkland Lake ; R o u y n ; Patricia D istric t;

Sixteenth International Geological Congress; Institution Manitoba ; New Beryl Mining Industry.

of Mining Engineers’ Summer Meeting; Report T n T ia n -n ^ c 'h n rc r 1 HO

of the Director of the Geological S u rv ey ; “ The J U i i a i l l i e s U U r g ... 1UZ Mines Handbook’’; International Safety in Mines Phenacite in the Transvaal; Interesting Finds in Conference at Buxton ; British Columbia Mineral Rhodesia ; A Rhodesian Gold Bounty (?) ; Northern Output for 1930; F.M.S. Mines R ep o rt; The Rhodesian G old; South African Tin Q uota;

Australian Gold Bounty. Platinum Outlook Brighter.

T h e R a n d G o l d G7 Pe r s o n a l ... 1 0 3 The latest stage of an old controversy on ore-genesis is

reviewed. T R A D E P A R A G R A P H S ... 1 0 3 T r a d e a n d F i n a n c e ■ • ■ ■ ■ ; 6 8 B ritis h C hem ical P la n t E x h ib itio n , 1931 . . 104 The main conclusions of the Macmillan Committee on

finance and industry are briefly examined. R u sto n -B u c y ru s No. 4 E x c a v a to r ... 105 F i f t y Y e a r s o f C h e m i c a l E n g i n e e r i n g 6 9 T h e W a tts V a rio m e te r ... 106 Attention is directed to the Jubilee Celebrations of the , _

Society of Chemical Industry and to the Chemical JYlE T A L M A R K E T S ... 1 0 7 Plant Exhibition.

Re v i e w o f Mi n i n g 7 0 St a t i s t i c s o f Pr o d u c t i o n... 1 0 9

Ar t i c l e s Pr i c e s o f Ch e m i c a l s ... I l l

T h e R u h u h u C o a lf ie ld s , T a n g a n y i k a S h a r e Q u o t a t i o n s ... 112

1 e r r i t o r y . ^

G. M . S to c k le y a n d F . O a te s 7 3 M i n i n g D i g e s t

The results are given of a survey over the coal areas of the G old M etallu rg y in C a n ad a . . C .S .P a Y S O U S 113 samples. baSin aad ° f preliminary tests on outcrop H a ll-In te rs ta te , L o st P ilg rim M ines, Id ah o

a'' i ri ' 1» *■ ■ > S. C am pbell 11 a

G r a n b y - 1 y p e M i n e C a r s r

C . M . C a m p b e ll 9 2 T h e T e s tin g of C hrom e O re . . L . W ein b erg 118 In this article it is shown how alterations in mining M ill R e tu rn V alu es C.C. F re e m a n 11 9 methods changed the outlook at the Phoenix mines T h e S la rk -T i n e R o n e w a v M M oore 121 of the Granby Consolidated Mining, Smelting, and i n e S IacK L m e r x o p e w a y ...m . m o o re 1 2 1

Power Company. T a s m a n i a n S t a n n i t e O r e

B o o k R e v i e w s D r . F . L . S tillw e ll 1 2 3

S ch n eid erh o h n a n d R a m d o h r’s " L eh rb u c h S am pling C yanide-G old Bullion

d er E rz m ik ro s k o p ie ,’’ Vol. 2 C. O. A . T h o m a s 124

D r . W . R . J o n e s 9 5 O re-L eaching J. D . S u lliv a n a n d E . O. O strea 125 S m ith so n 's " P a tte r n s fo r G eological R elief

M odels ” ... D r. M u r r a y S tu a r t 9 6 SHORT NOTICES ... 1 2 6 Ne w s Le t t e r s Re c e n t Pa t e n t s Pu b l i s h e d... 1 2 6 B r i s b a n e 9 6 Ne w Bo o k s, Pa m p h l e t s, e t c... 1 2 7 Production a t Mount Isa ; Eulogistic Speeches ; Mining

Work a t Mount Isa ; Overseas Capital for Mining; C O M P A N Y R F P O R T S 1 ? 8

The Mount Coolon O ptions; A Promising O utlook; x...

Queensland Coal In d u stry ; Broken Hill Central Ex-Lands Nigeria; Ipoh T in ; Kent (F.M.S.) T in ; Kramat Power P la n t; Broken Hill Block 14; Bendigo P u la i; Otavi M ines; Pena C opper; Rhodesia Broken H ill;

Goldfield. Tin Properties.

V a n c o u v e r 9 8 Di v i d e n d s De c l a r e d ... 1 2 8 GclBridge RiverVPlace^Minhig6; NomMetalli’c Mnerals.’ N E W C O M P A N IE S R E G I S T E R E D ... 1 2 8

2—4 65

E D I T O R I A L

I N view of th e generally adverse economic conditions th ro u g h o u t th e world, th e com m ittee on organization of th e 16th In te rn a tio n a l Geological Congress has decided to postpone th e m eeting of th e congress u n til Ju n e, 1933.

T H E Sum m er G eneral M eeting of th e In s titu tio n of Mining Engineers, p o st­

poned from Ju ly 8, will now be held from Septem ber 23 to Septem ber 25, in M anchester, th e program m e originally o u t­

lined and circulated to m em bers being ad h ered to.

I N his r e p o r t1 for 1930 th e D irector of th e Geological Survey of G reat B ritain reveals th a t fu rth e r experim ental work has been carried out in geophysical prospecting. This includes surveys in Scotland and L eicestershire respectively w ith a v ertical m agnetom eter an d a new ty p e of sm all E otvos torsion balance, details of w hich are to be published later.

T H E eighteenth volum e of “ T he Mines H andbook ” 2 m akes its appearance this m onth, th e previous volum e having been published in 1926. T his com pendium of inform ation of th e m ining in d u stry of th e A m erican continent first appeared in 1900 as th e “ Copper H andbook ” an d it h as now so grown in size as to be issued in two p arts, th e first an d b y far th e larger covering all th e com panies operating in th e U nited S tates and its dependencies an d th e second C anada, Mexico, an d C entral and South Am erica.

D E L E G A T E S from th e U n ited S tates, France, Belgium , an d G erm any a tte n d e d th e In te rn a tio n a l S afety in Mines C onference held a t th e B u x to n R esearch S tatio n from J u ly 11 to J u ly 17. The m eeting originated as th e resu lt of th e visit

1 S u m m ary of P ro g re ss of th e G eological S u rv e y of G re a t B rita in , 1930, P a r t I. P ric e 2s. L o n d o n : H .M . S ta tio n e ry Office.

2 “ T h e M ines H a n d b o o k ," V olum e X V III. P a r ts I a n d I I . C loth, o c ta v o , 2,870 pages. P ric e $25, o r £5 5s. N ew Y o rk : M ines In fo rm a tio n B u re au ; L o n d o n : T h e T ech n ica l B ookshop, 724, S a lisb u ry H ouse, E .C . 2.

to th is co u n try of Mr. G. S. Rice, th e Chief Mining E ngineer of th e U.S. B u reau of Mines, in 1923. D iscussions w ere confined to th e subjects of explosives and explosions. As a resu lt of th e friendships an d alliances form ed, how ever, closer association in all m a tte rs affecting sa fety in coal m ining m ay be expected to follow.

F IG U R E S w hich are now available show th a t th e m ineral o u tp u t of B ritish C olum bia reached a new high level for 19?9, although th e value of th e p roduction at

$55,391,993 was 18-8% less th a n for che previous year, consequent on th e fall in silver and b ase-m etal prices. Increased q u an titie s of gold, silver, lead, an d zinc and a decreased am o u n t of copper were recovered.

T he gold o u tp u t of th e D om inion during 1930 a t 2,102,068 fine ounces also established a record and definitely places C anada in the position of being th e w o rld ’s second largest producer of th e precious m etal.

I SSU ED as a su p p lem en t to th e F.M.S.

G overnm ent G azette of Ju n e 5, 1931, th e rep o rt of th e ad m in istratio n of th e Mines D e p a rtm e n t an d on th e m ining industries of M alaya for 1930 p ay s trib u te to th e stern fight p u t up an d th e philosophic spirit displayed by th e Chinese m ine owner and his em ployees in face of th e fall in th e price of tin to a level below w hich it w as n o t generally believed he could continue to operate.

T he o u tp u t from E uropean-ow ned m ines in 1929 an d 1930 w as g reater th a n from th e Chinese-owned properties. In th is connexion interesting figures are published of th e p e r­

centage o u tp u t b y different m eth o d s as follows :— B y dredging, 38% ; b y gravel pum ping, 43% ; b y hydraulicking, 7% ; by open-cast w orking, 4% ; by lode m ining, 5% ; b y dulang w ashers, 2% , and b y oth er m ethods, 1% .

T H E recently-aw arded b o u n ty of one

pound per ounce on all gold m ined in

A ustralia in excess of th e average production

of th e p ast three years is to be reduced to

ten shillings as p a rt of th e Com m onw ealth

G overnm ent’s schem e for econom y in public

expenditure and th e rig h t is reserved of

again reducing the b o u n ty if th e exchange ra te shows a fu rth er increase. This, it has been p o in ted out, is n o t such a h ard sh ip on th e gold producers as it appears a t first sight, in view of th e advan tag e which th e y now possess in th e ra te of exchange. Thus th e b o u n ty as now fixed, allowing for the exchange, is practically the same as originally proposed an d is equal to a reduction of one shilling on every rise of three per cent, in the exchange. T he producers have been prom ised th a t any backw ard m ovem ent of th e exchange will be m et by a corresponding increase in th e bounty, w hich would give them th e full 20s. again should the exchange become norm al. T he gold producers will be fu rth er assisted as a result of an agreem ent w hich has been reached w ith th e labour organizations w hereby th e m iners will not, as heretofore, tak e their fo rtn ig h t’s leave together. In th e p a st th is custom of sim ul­

taneous holidays during C hristm as and the New Year has necessitated th e closing of th e m ines and the sh u ttin g down of plant.

T h e R an d G old

The functions of th e geologist on a mining field are som ew hat sharply defined and mining m en are generally rea d y to ad m it th a t his w ork is b o th necessary and useful.

N evertheless it is often difficult for the practical m an to appreciate th e h eated con­

troversies w hich arise over questions which to him are of a purely academ ic character.

I t should be rem em bered, of course, th a t such disputes are m erely th e outcom e of a search for tr u th and once th e tr u th is dis­

covered th e q uarrel dies an d useful w ork is able to begin from a new position. From such a stan d p o in t th e detached observer is able to view the controversy w ith equanim ity, for it is always possible to m ake use of new facts brought forw ard by th e protagonists of opposing theories, and th ere is no doubt th a t m any points of value to those responsible for th e developm ent of th e W itw atersrand goldheld have been bro u g h t out by the argum ents advanced by th e supporters of th e various theories which have been p u t forw ard to explain th e origin of th e gold on this held.

T he publication in May, 1930, of a paper by Professor L. C. G raton, of H arv ard U niversity, on th e origin of th e R and gold revived a controversy w hich has been in existence for m an y years. The subject was

review ed a t some len g th in th e

for Ju ly of la st year, w hen th e principles of th e m ain theories w hich are a t present held as to th e origin of th e gold in R and “ b an k et ” were outlined. I t was th ere sta te d th a t of th e three m ain theories, so well sum m arized by de L aunay in 1903 and w hich are known as th e placer, th e precipitation, and th e infiltration theories, only th e first and th e last are now widely held, and, fu rth er, in S outh A frica a t least, it is certain th a t th e preponderance of opinion is in favour of w h at m ight be term ed a modified placer theory. I t was th u s evident th a t th e publica­

tion of Professor G rato n ’s paper, which supported a h y d ro th erm al origin for th e gold and w hich therefore upheld th e infiltra- tionists, was bound to create considerable in terest and during th e p ast year m an y well- known geologist's have discussed his paper, either a t m eetings of or in w ritten co n trib u ­ tions to th e Geological Society of South Africa. T he excuse for fu rth er reference to th e m a tte r here is furnished by th e publica­

tion of an im p o rtan t contribution to the discussion by Dr. E. T. Mellor, whose work on th e W itw atersrand System is so well known and whose th eo ry of some sort of deltaic site for th e deposition of th e system has been widely supported, especially after proving so useful in in terp retin g th e peculiarities of distribution of th e Main Reef L eader on th e F a r E a st R and.

Professor G rato n ’s paper contained num erous references to Dr. Mellor’s w ork and his em phatic statem e n ts to th e effect th a t he could see no reason to refute th e dom inant philosophy of ore-deposition—

which, of course, involves a m agm atic origin for all p rim ary ore-bodies—and th a t he could only accept a h y d ro th erm al hypothesis in th e case of th e R an d gold was bound to lead to an equally em phatic reply a t some future period. Reviewing th e contributions of both these authorities it m ust be ad m itted th a t th ere were m any statem en ts in Professor G rato n ’s paper which seemed to indicate th a t he held a th eo ry before exam ining th e facts an d th a t in consequence all facts were exam ined and correlated in th e light of pre­

conceived views, so th a t his conclusions could

only be accepted after a careful exam ination

of his reasoning. Such an exam ination leads

one to feel th a t th e new explanations are at

least as difficult to accept as were th e old,

and it would seem th a t th ere is m uch yet

to be explained before either th eo ry can be

held to be proved. N evertheless, th e weight

6S

of th e evidence ap p ears to be in favour of a secondary origin for th e gold and th e enorm ous e x te n t of th e deposits un d o u b ted ly supports Dr. M ellor’s th eo ry of a deltaic or sim ilar origin. In addition, th e alm ost general acceptance of th e placer th eo ry by those m ost fam iliar w ith th e conglom erate reefs suggests th a t practical evidence is ra th e r in favour of th is th eo ry th a n th a t of infiltration.

T ra d e an d F in a n c e

T he feeling th a t som ething is drastically w rong w ith w orld affairs w hich has been generally experienced for some tim e is now being openly expressed and in m any places it has been acknow ledged th a t a sta te of em ergency, if it does n o t already exist, is a t least im m inent. In consequence m uch th o u g h t is being given to necessary reconstructions of th e w orld’s financial edifice and a degree of clarity is given to th e position, a t a n y ra te as far as it concerns th is country, b y th e publication of th e R ep o rt of th e C om m ittee on F inance and In d u s try ,1 of w hich Lord M acmillan was th e chairm an. T he M acmillan Com m ittee

— to give it its short title —w as set up in N ovem ber, 1929, p a rtly in response to criticism s of th e m o n etary policy of this c o u n try and p a rtly to m eet allegations th a t ad eq u ate assistance to depressed industries h ad n o t been forthcom ing from th e banks. In addition, som e explanation was required for th e far-reaching effect of financial speculations in any one p a rticu lar country. T he com m ittee’s term s of reference w ere to inquire into banking, finance, and credit an d to m ake recom m endations calculated to enable these agents to prom ote th e developm ent of tra d e and commerce and th e em ploym ent of labour. Its rep o rt is divided into tw o p arts, th e first being historical an d descriptive and th e second containing its conclusions and recom ­ m endations, while th e re are, in addition, various addenda and reservations. The principal conclusions arriv ed a t are : (1) A dherence to an in tern a tio n a l gold stan d a rd should be continued ; (2) a rise in com m odity prices tow ards th e 1928 level is to be recom m ended, cen tral b an k s to w ork for sta b ility of price le v e l ; (3) th e currency of th is co u n try should be a m anaged system , th e m anaging a u th o rity being th e B ank

1 R e p o rt of th e C o m m itte e on F in a n ce an d In d u s try , J u n e , 1931. P ric e 5s. L o n d o n : H.M . S ta tio n e ry Office.

of E n g la n d ; (4) th e B a n k of E n g lan d should be em pow ered to increase its norm al note circulation in order to give a d d itio n al tem p o rary e lasticity and should b y law not be p e rm itte d to allow its gold reserve to fall below £75,000,000, except tem p o rarily by perm ission of th e T r e a s u r y ; (5) arran g em en ts betw een th e jo in t-sto c k b anks and th e cen tral b an k should be modified in such a w ay as will provide for th e m aintenance of cheap credit, and (6) fu rth er develqpm ent of financial organization should be aided b y th e settin g u p of in stitu tio n s to act as financial advisers to in d u strial com panies.

T h e m ain conclusions of th e re p o rt w hich principally concern us h ere are those w hich urge th a t a re sto ra tio n of world price levels is u rg e n tly needed and w herein price sta b ility on an in te rn a tio n a l basis is suggested. I t is proposed th a t th e ce n tra l b an k s of th e w orld should ad o p t th e objective of raising prices in order to p rev en t stab ilizatio n a t present levels, which, th e re p o rt subm its, would be disastrous for all countries. W hen prices becom e ap p ro p riate to existing wages and salaries it is recom m ended th a t the m o n etary policy should endeavour to keep those prices stable, th is being th e principal reason for suggesting th e placing of th e m o n etary system of th is co u n try under control. I t is recognized th a t, how ever desirable these objectives m ay be, th ey are not easy of achievem ent an d can only be reached b y in te rn a tio n a l agreem ent.

F u rth e r a tte n tio n should, p erh ap s, be given to th e recom m endation of th e com m ittee th a t adherence to an in te r­

natio n al gold sta n d a rd a t existing p a rity is to be desired, especially as it has been recognized th a t an insufficiency of gold will u n d o u b ted ly occur in th e future, w hen a fall in prices is inevitable. N ev erth e­

less, it is considered th a t, given in tern atio n al good will and u n d erstan d in g , dangers th reate n in g price levels from th is source are so rem ote th a t consideration of this side of th e problem m ay be postponed.

T he insistence on th e fact th a t th e gold

sta n d a rd m u st be allowed to function

freely is sufficient recognition of th e p a rt

th a t m aldistribution of th e w orld’s gold

has played in creating th e presen t depression

an d herein lies th e cause of th e restiveness

m anifested in m any q u a rte rs b y a dem and

either for a new sta n d a rd of values or for

th e reh ab ilitatio n of silver by a re tu rn to

a bi-m etal stan d ard . T he m ain difficulty w hich lies in th e w ay of fixing th e gold- silver price ratio has recently been expressed as th e im possibility of relating th ree m ovable and moving objects, for it is clear th a t, while goods m ay be quo ted in term s of gold or of silver, th e ra tio of gold to silver will v a ry w ith th e sep arate quotations.

N evertheless, it is th e opinion of m any people th a t th is problem m ight well be evaded a t th e p resen t' ju n c tu re b y th e establishm ent of an in tern atio n al price ratio for th e tw o m etals.

F ifty Y ea rs o f C h e m ic a l E n g in e e r in g

T he jubilee celebrations of th e Society of Chemical In d u stry were held in London last m onth. W hile th e field covered by th e society is now all-em bracing, it should not be forgotten th a t th e bran ch of technology which has come to be known as chem ical engineering has its roots deeply im planted in th e ancient a rt of m etallurgy.

T he m etallurgist it was who first grappled w ith th e problem of applying th e processes of pure chem istry to in d u strial usage and from th e industries of copper, lead, and zinc extraction—some of th e oldest in this country—sprang a m u ltitu d e of ancillary industries which form ed a nucleus of th e great chem ical in d u stry as we know it to-day. Im p o rtan t as are th e great dye- stuffs, alkali, and o th er non-m etallurgical industries in th e world, th e industrial chem ist has a three-fold deb t to th e m etallurgist, who developed first a technique, th en a generation of chem ical engineers, and finally produced m etals and their alloys of a p u rity and stre n g th which alone have m ade possible th e im plem ents and equipm ent a t th e disposal of th e in d u stry to-day.

A ppropriately enough th e celebrations opened in th e G uildhall, w here th e society signified its appreciation of th e valuable support its m em bers had received from the Corporation and L ivery Companies of the City of London b y presenting suitable m em orial plaques an d addresses to each of th e bodies concerned, p articu lar a tten tio n being p aid to th e princely donations made to th e City and Guilds Engineering College, th e presen t im m ediate neighbour of th e R oyal School of Mines. This interesting function was followed b y th e presidential address of Sir H a rry McGowan, th a n whom no one is b e tte r qualified to speak of th e

close association of chem istry and industry, holding as he does th e position of chairm an of th e greatest chem ical combine th e world has ever known. Of th e various sub­

sections into w hich th e general m eeting subsequently broke th a t held under th e auspices of th e F uel Com m ittee is of chief interest to m ining men. H ere th e discussions centred round th e question of producing oil from coal, w ith a view to rendering this country independent of foreign supplies of a fuel which is displacing coal more and more every day. F rom these it appeared, as it has in previous discussions, th a t hydrogenation, in th e light of present knowledge, provided th e m ost prom ising future, especially in its application to the products of low -tem perature carbonization.

Dr. D unstan, th e chief chem ist of the Anglo-Persian Oil Company, in dealing w ith another im p o rtan t subject, a ttrib u te d over-production of oil to increased technical efficiency, which brings unem ploy­

m ent in its trail. This, unfortunately, is equally tru e of th e m etal industries, where reduction of mining costs, im prove­

m ents in recovery, and similar advances have b rought us a toll which is now hard to pay. This, however, m ay be regarded as b u t a lim ited view, for corresponding advances in other industrial spheres have been taking place which u n fortunately hav e failed to m aintain th a t level of consum ption which m ight have helped to preserve th e balance.

Any reference to th is com m em oration would be incom plete th a t om itted to m ention th e Chemical P la n t Exhibition, w hich was held concurrently and which proved to be one of th e m ost interesting of its kind th a t can be rem em bered. Some a tte n tio n is paid to th e individual exhibitors elsewhere in th is issue, so th a t reference here will be confined to th e research section.

This was organized b y th e Chemical Engineering Group and consisted of a rem arkably com prehensive display to illustrate th e service rendered b y th e various research organizations, chief am ong which should be m entioned th e N ational Physical Laboratory, th e B ritish N on-Ferrous Metals R esearch Association— of w hich more detailed m ention was m ade here last m onth

—and th e Fuel Research Station. Specimens

and ap p aratu s testified visually and their

guardians eloquently to th e great benefit

th a t persistent technical research confers

on h um anity.

R E V I E W O F M I N I N G

In tro d u ctio n .— Conditions during th e past

m onth can h a rd ly be said to have im proved, a lack of confidence being evident in nearly all com m odity m arkets. Prices of m etals have been generally disappointing. W hilst th e position of tin m ay be regarded as b e tte r th a n a m onth ago, copper has shown m arked weakness, th e price on A ugust 11 of £32 6s. 3d. being th e low est recorded.

As to zinc, th e position has been som ew hat stren g th en ed by th e renew al of th e cartel, as sta te d in the M etal M arkets report.

T r a n sv a a l.—T he o u tp u t of gold on th e

R and for Ju ly was 872,198 oz. and in outside d istricts 44,645 oz., m aking a to ta l of 916,843 oz., as com pared w ith 897,750 oz. in Ju n e. T he n u m b er of n ativ es em ployed in th e gold m ines a t th e end of th e m onth to talled 208,155, as com pared w ith 207,209 a t th e end of Ju n e.

Reference was m ade here last m onth to th e striking of th e R andfontein leader in th e No. 2 n o rth sh aft of R an d fo n tein E sta tes.

F u rth e r advice has now been received to th e effect th a t th e W est R eef was intersected in th e sam e sh aft a t a d e p th of 4,536 ft., assays a t th is p o in t showing 6 dw t. of gold over a w idth of 41 in., th e reef dip being 27°. A t th e oth er extrem e of th e R an d field th e D aggafontein com pany announce th a t th e reef has been encountered in No. 3 sh a ft a t a d e p th of 3,880 ft., th e average value a t th is p o in t being 26'48 dw t. over

1017 in.

A t a special m eeting of th e M arievale Nigel Gold Mines and E sta te , to be held in S eptem ber, a resolution will be m oved to confirm a provisional agreem ent w hich has been concluded w ith th e Union C orporation in connexion w ith th e disposal of th e com pany’s p roperty. T he Mjirievale Nigel ground adjoins th e farm V lakfontein No. 21, in th e H eidelberg d istrict, w hich is already being exam ined b y th e Union Corporation, and th e proposed agreem ent gives th em th e rig h t to prospect th e area and th e option, u n til Ju n e 30, 1935, to purchase it.

T ow ards th e m iddle of la st m o n th it was announced by th e M inister of Mines in th e Union G overnm ent th a t it was n o t proposed to a c t on th e in te rim re p o rt of th e Low G rade Ore Commission, th e in ten tio n being to aw ait th e final rep o rt.

T h e d e p a rtu re of Mr. A lfred Jam es for S outh A frica was m entioned in th e

for O ctober la st an d it h a s now been announced th a t he is in stitu tin g legal action

against various R an d com panies in connexion w ith th e use of certain p a te n t processes of gold ex tractio n , th e rig h ts of w hich are sta te d to be held b y him .

Shareholders of th e W olhuter Gold Mines have been advised th a t th e balance of th a t com pany’s assets has now been realized and it is expected th a t th e first and final liquida­

tion d istrib u tio n will am o u n t to about Is. l i d . p er share.

D ia m o n d s.—T h e h ead office

of th e P rem ier m ine is being tra n sfe rre d to K im ber­

ley and it is s ta te d th a t th is tow n will becom e th e centre of a group system of diam ond houses sim ilarly organized to th e gold m ine groups in Joh an n esb u rg . The controlling board is to be increased from 12 to 16 m em bers in consequence of th e De B eers’ larger interests.

S o u th ern R h o d e sia .—T h e

o u tp u t of gold from S outhern R hodesia during Ju n e was 44,118 oz., as com pared w ith 43,731 oz. for th e previous m o n th and 45,208 oz. in June, 1930. O th er o u tp u ts for Ju n e w ere : Silver, 5,647 oz. ; copper, 59 to n s ; coal, 51,954 tons ; chrom e ore, 3,305 to n s ; asbestos, 1,317 tons, an d m ica, 3 tons.

N orth ern R h o d esia .—T h e accounts of

T an g an y ik a Concessions for 1930 show a decrease in profits of £249,289 to £232,866, which, w ith th e balan ce of £475,951 brought in, gave an available to ta l of £708,817. Of th is am ount £179,000 was ta k e n for income- ta x provision, £50,000 w ritte n off share values, and £100,000 tra n sfe rre d to reserve, leaving a balance of £379,817 to be carried forw ard. T he re p o rt shows th a t th e output of copper during 1930 b y th e U nion Minière du H a u t K a ta n g a w as increased to a record to ta l of 138,949 tons, th e proved reserves of th e m etal being e stim a te d a t 5,000,000 tons.

O ther im p o rta n t in te re sts of th e com pany are in th e B enguela R ailw ay, ju st com pleted, and in th e R h o d esia-K atan g a com pany, which is developing th e K an san sh i mine, for w hich a tre a tm e n t p la n t capable of pro­

ducing 50,000 to n s of copper p er ann u m is being designed.

T h e rep o rt of th e Zam besia E xploration Com pany, w hich is a large sh areh o ld er in T ang an y ik a Concessions, shows th a t during 1930 a profit of £39,167 was m ade, as com­

pared w ith £106,502 th e previous year.

D uring 1930 Loangw a Concessions carried

on prospecting and geological m apping,

diam ond drilling bein g em ployed w hen

indications w arran ted , b u t so far no m ineral

deposits of m aterial value have been discovered. R eference is m ade to good gold assays of q u artz float found in th e con­

cessions, b u t th e value of th e find is not yet known. T he B ritish South A frica Com pany have been app o in ted consultants to the com pany, in place of R hodesian Anglo Am erican.

The th ird u n it of th e p lan t a t th e Roan Antelope mine was s ta rte d up on Ju ly 25.

Gold C oast.—An interesting featu re in

the developm ent rep o rt of th e A shanti Goldfields for J u ly is th e cu ttin g of the A shanti reef by extension No. 12 cross-cut N.E. from No. 16 level, a w idth of 5 ft.

being revealed, th e ore having an average assay value of 5'5 dw t.

N igeria.— O perations

of Ju g a Valley Tin Areas during th e year ended F eb ru ary 28 last were on a v ery restric ted scale, the o u tp u t having decreased to 153-| tons of tin concentrates. As it was found uneconom ical to work th e p lan ts th e y have been closed down, th e tin produced being won by tributors. T he accounts show a loss of

£6,872,. increasing th e d ebit balance to

£19,143.

T he rep o rt of th e N igerian E lectricity Supply Corporation for th e y ear ended F eb ru ary 28 last shows th a t electric power was first supplied in Ju n e, 1930, th e com pany being in a position to offer a perm anent supply of cu rren t to th e tin m ines a t th e end of October, and th e power house has since continued to function satisfactorily.

The accounts for th e year show a profit of

£17,524, a balance of £16,625 being carried forward.

A ustralia.—The rep o rt of th e Broken

Hill P ro p rietary Block 14 for th e six m onths ended March 31 last shows th a t operations at th e mine were a t a standstill for th e period, th e price of m etals being too low to w arran t resum ption of operations. The working loss for th e six m onths am ounted to £2,821, o th e r expenses m aking th e to ta l n et loss £8,244. T he credit balance now stands a t £11,189. T he p lan t is being kept in good condition w ith a sm all staff.

Cabled advices from M elbourne give th e profit of th e B roken Hill P ro p rietary com­

p any for th e year ended May 31 last as

£83,257, a fte r providing £232,752 for deprecia­

tion an d £64,659 for deb en tu re interest.

This figure com pares w ith £161,890 in th e previous year.

¿C ontract m iners em ployed a t B roken Hill b y th e Zinc C orporation ceased w ork last

m onth owing to a reduction in prices offered, th e m anagem ent being forced to suspend oth er underground operations. U p to the tim e of going to press no news had been received of th e settlem en t of the dispute.

Shareholders of th e Boulder Perseverance have been inform ed th a t th e com pany proposes to issue £50,000 of 10-year profit- sharing notes in denom inations of £5, £50, and £100. In te re st will be a t th e ra te of 10% and, in addition, th e notes will carry the rig h t to 50% of th e profits of th e com pany as from Ja n u a ry 1 next. T he notes will be repayable on Ju n e 30, 1911, a t th e ra te of

£120% , but m ay be redeem ed at any tim e after June, 1936. The proceeds of th e issue are to be utilized for th e installation of new tre a tm e n t plant.

A W iluna Gold Corporation circular states th a t during Ju ly 25,952 tons of ore was tre a te d for bullion valued, w ith exchange allowance, a t £36,700, working costs being

£26,241. W hile th e power plant is running more steadily, a restriction of ou tp u t to 30,000 tons m onthly is an ticip ated to m eet a lack of capacity in the grinding section.

Mr. C. O. Lindberg has been asked to m ake a fu rth er report on the property.

New Z ealand.— Interesting developm ents

on th e No. 5 level of the Jun ctio n E astern area of th e W aihi Gold Mining Company provide yet another instance of a mine dying hard. A reef averaging 3 |f t. in w idth intersected south of th e M artha lode has been driven on for 14 ft., th e ore assaying

£4 Is. per ton. In addition, driving has been com m enced in a n orth-easterly direction on q u artz intersected south of th e main shaft.

This averages 1 ft. in w idth and th e first 7 ft. was in high-grade sulphide ore.

In d ia.—W orking places in th e N undy-

droog mine h ad been generally freed from th e poisonous gases resulting from th e serious fire by th e m iddle of last m onth and stoping and developm ent have been resum ed. Milling was expected to re s ta rt by th e end of th e m onth.

On th e Mysore a serious rockburst occurred on J u ly 22 in th e E d g ar sh aft, th ree m en being reported as missing. D am age to the brickw ork of th e sh aft was rep o rted to be qu ite extensive and it was estim ated th a t a t least th ree weeks would be required for th e com pletion of repairs.

M alaya.—D uring th e year ended M arch 31

last M alaysiam Tin tre a te d 539,030 cu. yd.

of ground, recovering 2 6 2 | tons of tin

concentrates, w hich realized £18,730. The

profit for th e y ear was £2,789 and, afte r w riting off th e d eb it balance b ro u g h t in, th ere rem ained a sum of £32 to be carried forw ard. A t th e annual m eeting h eld last m onth it was agreed th a t 100,000 of th e unissued shares should be called preferred ordinary shares and th a t th e 595,504 issued and th e rem aining 304,496 unissued shares should be called ordinary shares, th e preferred shares to have th e right to a fixed preferential dividend of 7% and to p articip ate in any balance of profits. I t is proposed shortly to issue th e preferred ordinary shares in order to finance th e purchase of th e Glami property.

A t a m eeting of shareholders of Siput Tin, held la st m onth, it was decided th a t th e com pany should go into v o lu n tary liquidation, efforts to raise additional w orking capital having proved unsuccessful.

T he accounts of T eja M alaya Tin Dredging for 1930 show a loss of £8,977, increasing th e d ebit balance to £34,461. T he com pany’s claim against th e dredgebuilders was settled during th e year, th e com pany receiving cash and spare p a rts to th e value of £12,072. T he o u tp u t of th e tw o dredges was 337-47 tons.

In a circular accom panying th e rep o rt shareholders are in v ited to subscribe to an issue of loan notes carrying in tere st a t 10%

per an n u m and rep ay ab le a t 105% on or before Ju ly 31, 1936, th e am ount raised to be lim ited to £30,000, w hich it is estim ated will enable th e com pany to carry on operations and provide for d e b en tu re interest.

K orea.—Conflicts betw een K oreans and

Chinese hav e caused so m uch dam age to th e p ro p e rty and stores of th e Chosen C orporation th a t it has been tho u g h t p ru d en t to postpone th e p ay m en t of dividend No. 2 pending fu rth e r advices. T his dividend, 3fd. per share, was declared in M ay last and w as due to be p aid la st m onth.

P a n a m a .— Shareholders of P an am a Cor­

poration were inform ed last m onth of progress on th e various properties. A t th e R em ance broken ore aw aiting tre a tm e n t was restricting w ork in th e m ine, b u t it was expected th e com plete mill would be running a t an early d ate. U p to J u ly 13, w hen th e statem en t was issued, th e mill h ad tre a te d 800 tons of ore of an average value of 36s. p e r ton, th e ex tractio n being 92-3%. Cyaniding com m enced on Ju n e 12 and th e p recipitation p lan t on Ju n e 17, th is running a t a reduced capacity pending th e installation of a cone- crusher. No proper clean-up h ad been m ade a t E l Mineral, w here th e w ork was still in its initial stage. On th e Sabalo section 14,000 cu. yd. of ground h ad been tre a te d in opening up th e paddocks, in addition to

ab o u t 10,000 cu. yd. of overburden, b u t no clean-up h a d been m ade.

S p a in .—Shareholders of

Tigon Mining and F inance were inform ed last m onth th a t th e operations of th e tre a tm e n t p la n t to d a te h ad n o t proved w holly satisfacto ry and th a t fu rth e r w ork on th e extension had been suspended for th e tim e being. Four furnaces of an im proved Gill ty p e hav e been installed and these h av e proved so satis­

factory th a t a second four are u n d er construc­

tion. On th e Chile p ro p erties production has been curtailed, stocks having accum ulated to an e x te n t which m akes th is step advisable.

U nrest am ong m iners in th e H uelva d istrict, owing to th e Rio T in to com pany reducing th e w orking w eek to five days, is giving cause for som e anxiety.

C y p r u s . —

T he re p o rt of th e Cyprus A sbestos C om pany for 1930 shows a profit of £245. A fter tran sferrin g £10,000 to Stock D epreciation R eserve th e balance carried forw ard was reduced to £29,072. D uring the y ear 177,161 to n s of ore w as m illed and 7,256 tons of fibre produced, th e recovery being 4-1% , as com pared w ith 3-4% the previous year. A t a m eeting to b e held in C yprus n e x t m o n th it will be proposed th a t th e u n d ertak in g should b e sold to a new com pany, called th e C yprus an d General A sbestos Com pany, h av in g a c a p ita l of

£750,000, divided in to 150,000 6% redeem ­ able preference shares of £1 each a n d 600,000 ordinary shares of £ l each. Shareholders are to be in v ited to ap p ly for shares in the new com pany cred ited as 18s. paid, the balance of 2s. being p ayable Is. on allotm ent and Is. in D ecem ber next. I t is considered th a t th e alte rn a tiv e to acceptance of recon­

struction will be th e w inding-up of the com pany.

C o n so lid a ted T in S m e lte r s .— F o r th e

nine m onths to J u n e 30 la st th e accounts of Consolidated Tin S m elters show a profit of £177,698. A dividend of 5% h as been declared, th e balance carried forw ard being

£81,513. C u rtailm en t of sm elting operations has been m et by centralizing operations a t certain p lan ts and th is procedure will be continued if necessary.

T in .—A fter th e m eeting of th e In te r ­

n ational Tin C om m ittee on J u ly 21 la st th e following ann u al quotas for th e four p a r­

ticipating countries were issued, covering th e period Ju n e to S e p te m b e r; N etherlands E a st Indies, 25,167 t o n s ; N igeria, 6 733 tons ; Bolivia, 26,827 tons ; M alaya,’ 45,369 tons. W ith regard to th e excess o u tp u t of M alaya, arrangem ents hav e been m ade to

tak e th is off th e m a rk et for th e tim e being.

TERRITORY

By G. M. STOCKLEY, A.R.C.S., D.I.C., F.G.S., and F. OATES, A.R.S.M., B.Sc.

T h e authors, b o th officers of the T an g an y ik a G eological Survey, give the results of a survey over the coal areas in the R u h u h u basin a n d of p relim inary tests in ou tcro p sam ples.

I n t r o d u c t i o n . —

Search for coal in E ast Africa com m enced as far back as 1860, when S u ltan Seyid B argash of Zanzibar had the M akaa-Ituli outcrop on th e Middle R uvum a (on th e Portuguese border) examined. Loads of coal were brought to Zanzibar b y dhows and te st experim ents were carried out on several of th e S u ltan ’s steam ers. H asslacher, a m ining engineer who carried o u t a num ber of surveys of prospects for th e G erm an G overnm ent, says th a t even th e erection of a gasworks was under consideration. Since th e n search for reasonably thick seam s of coal has gone on in term itten tly , now by G overnm ent, now by p riv ate com panies. B o th in K enya and in T anganyika (then G erm an E ast Africa) th e respective G overnm ents have endeavoured to find a coalfield w hich would supply th e ir railways, b u t, so far, w ithout success. All the coal a t present used b y th e K enya and U ganda railw ay an d th e T anganyika railways is shipped from N atal.

W ith th e exception of th e coalfields in Portuguese E a st Africa and N yasaland (chiefly th e Sum bu an d Mt. W aller Coal­

fields) recent discoveries have all been m ade in T anganyika. Coal has been know n near M anda as far back as 1890 and B orn h ard t carried out an exam ination in 1895-7 of a small coalfield in th a t locality, condem ning it. He also exam ined another field to th e north of Lake N yasa, n o t far from T ukuyu near th e K ivira-Songw e R ivers and this proved to be m ore prom ising, as seams of economic thickness were found, some 8 m etres of coal occurring in several seams, slightly sep arated from each other b y th in shale intercalations. R um ours of coal also came from n ear Songea, b u t were not actively followed up. Coal was reported to the G erm an G overnm ent from th e Lum echa R iver by J o h n B o o th ; in G erm an file No. G.2408 1 a le tte r from B ooth shows th a t the outcrop is ab o u t a d a y ’s m arch n o rth ­ west of Songea in th e L um echa and N yaka Rivers. He says he could not give an estim ate of th e thickness, b u t “ th e coal lies so high an d free, under a yellowish clay surface soil th a t considerable qu an tities

1 S e c re ta ria t. D a r es Salaam .

could be obtained w ith o u t g reat working costs ” . T h at was in 1902 and nothing has been done since on th a t area, which, if any deposit of value h a d been discovered, w ould surely have a ttra c te d th e atte n tio n of those locally interested in mining. A ttach ed to th a t file is a m em orandum in which it is sta te d th a t a sam ple of the coal gave an ash percentage of 27’06.

Then, in 1907, th e D istrict Officer Songea, while journeying along th e Portuguese border, three days’ m arch from Songea, m ade another discovery of coal, which proved to have an ash content of 25T2%

and a calorific value of 4,778 sm all calories per gram (equivalent to 8,600 B.T.U.

per lb.).

O ther rum ours of coal came from near th e Central R ailw ay a t Kilosa, b u t Scholz, th e G erm an governm ent geologist, failed to find any. A fter th e w ar this area was again exam ined and one of our colleagues, F. B. W ade, found an im pure coal seam w ith a m axim um thickness of 42 in. An analysis however, proved it to be m ore of the n atu re of a carbonaceous shale th a n true coal, th e ash co n ten t being 63% . This area was referred to by Mennell in a paper read last year before th e In tern atio n al Geological Congress a t P retoria. Mennell h a d carried o u t several exam inations for p riv ate companies looking for coal in the coastal area, in th e h in terlan d of Mombasa, near Tanga, and along th e Rufiji close to th e P angani falls, b u t ap p aren tly w ith o u t success. In 1921, ju st prior to Mennell’s visit, Dr. E. O. Teale and Mr. F. B. W ade were engaged exam ining for th e T anganyika G overnm ent the various areas of known K arroo rocks w ithin th e coastal lowlands w ith a view to finding w orkable seams of coal. In the T anga area prom ising black carbonaceous shale was found, b u t no coal.

In th e Rufiji region a th in streak of coal was found in black shale, b u t nothing of prom ising thickness was discovered.

The best known coalfield in T anganyika

occurs on th e Ufipa P latea u an d was

discovered in 1914 b y F a th e r Poultier de

M ontechov of th e Chala Mission in the

Namwele valley. The G erm an G overnm ent

73

T H E M IN IN G MAGAZINE

Disusedmotorro»o

sent D r. K irschstein to exam ine the area.

It occurs 885 m etres above and 80-110 kilom etres from Lake T anganyika and is close to, b u t above, Lake R ukw a. Several seam s of coal are exposed in the Namwele valley an d are as follows : (1) U pper seam, flaky and poor quality, 106 cm. thick containing 39 cm. of coal ; (2) m iddle seam, pyritiferous, 262 cm. thick w ith 160 cm.

of c o a l; (3) lower seams, m ore m assive th an the former, thickness 461 cm. w ith 97 cm.

of coal. I t was considered a good coking coal an d th e ash varied from 19 to 28%.

Recently th e N yasaland M inerals exam ined the area extensively an d proved th e existence of w orkable coal seam s by boring. M arket and other conditions however delayed developm ent and work has been suspended.

All these areas are confined to th e K arroo form ation which is, of course, th e principal coal-bearing form ation in Africa. Coal has also been found to th e west of Kilwa and Lindi in the younger form ations near to the coast, b u t no definite details of thickness or extent have y e t been determ ined.

The latest discovery is th a t by th e T an ­ ganyika Geological Survey of the num erous coalfields in th e R uhuhu basin, south and south-east of th e Livingstone M ountains.

This region, situ a te d to the east of Lake Nyasa, comprises 1,300 square miles an d lies both in the N jom be an d Songea districts.

Between th e lake an d th e old Njombe- Songea road is an area of K arroo rocks

Fi g. 2 . — Fa u l t Sc a r p— Ma n d a Be d s f a u l t e d a g a i n s t Gn e i s s— Ma n d a- So n g e a Ro a d.

Fi g. 3 . — Pa r t o f t h e 1 7 f t. Se a m, Mk a p a Ri v e r, Ng a k a Co a l f i e l d.

which has been let down by norm al faults betw een walls of gneiss. These boundary scarps are very im posing in some portions, although in much of th e area th e walls have been eroded, leaving broken rem nants in th e form of pyram idal hills. A t one point a t Ndem be M ountain, th e scarp has a precipitous face of 1,500 ft. T he country w ithin th e depression is n o t very m oun­

tainous, being in th e n atu re of ridges and low erosion scarps, which very seldom a tta in 500 ft. above th e surrounding country.

Kingori M ountain, which is situ a te d close to the R u h u h u -R u tu k ira confluence and th e Liham o and Likenuli ridges are the chief features in th e depression. From Kingori to th e east an d to th e south-w est a ridge extends an d is fairly prom inent and distinct. The general altitu d e of th e country from Lake N yasa to th e Njom be-Songea road rises from ab o u t 1,700 ft. to about 2,500 ft. a t th e H an g a-R u tu k ira confluence.

The cou n try around th is confluence rises

to ab o u t 3,000 ft. a t ab o u t seven miles b o th

to th e so u th and th e north. Thus generally

th e country is gently rolling broken by a

few low scarps. The drainage is tow ards

th e lake, th e principal river being th e

R uhuhu, which is th e largest river in th e

south-w estern regions of T anganyika and

m ay be com pared w ith other b e tte r know n rivers of th e T erritory, th e R u v u m a an d th e R uaha. The R u tu k ira, th e largest trib u ta ry , drains th e n o rth -eastern portion of th e area, while th e R u h u h u R iver drains th e m oun­

tainous cou n try to th e east of th e Livingstone M ountains. Three oth er large trib u ta rie s are th e L um echa R iver, draining th e so u th ­ eastern portion, th e N gaka, th e so u th ­ w estern m ountain region, and th e K etew aka, the' Livingstone M ountains to th e n o rth of Manda.

Fi g. 4 . — 1 7 f t. Se a m, Mb u y u r a Ri v e r, Ng a k a Co a l f i e l d.

G e n e r a l G e o l o g y . —

T he general geology of th e . rocks exposed an d th e stru c tu re of th e coalfields h a d n o t been previously determ ined an d th e Geological Survey was able to m ake fossil discoveries of sufficient u tility to enable a close correlation to be m ade of these s tra ta w ith th e coalfields and associated rocks of S outh Africa, Southern Rhodesia, and N yasaland. The Survey was able to prove th e existence of tw o rep tilian bone beds, w hich w ith other fossiliferous discoveries show th a t these rocks m ay be correlated from th e base of th e E cca to th e Lower Storm berg. I t was possible to divide these rocks into eight distinct divisions. These divisions have been based on lithological differences and on economic and palaeontological grounds. An unconform ity was proved betw een th e basal

Very nearly all th e best coal seam s are confined to th e Lower Coal Measures.

F rom a re p o rt on th e re p tilia n bone fragm ents from D r. S. H a u g h to n of the S outh A frican Geological Survey th e Lower Bone Bed is of B eaufort age ; th e Rhexoxylon

a M olteno age (Lower Storm berg) an d the

which therefore indicates an age from the Middle B eaufort to th e to p of th e M olteno Beds. I t is therefore certain th a t th e M anda Beds can be correlated w ith th e Chiw eta G rits of N yasaland w hich are of M olteno age ; th e K ingori S andstones an d th e Lower Bone B ed are included in th e B eaufort;

the rem ainder, down to th e base of th e B asal Sandstones an d Conglom erates, are correlated

1 Id e n tified b y J. W alto n , of G lasgow U n iv e rsity . 2 Id e n tified b y L. R . Cox, of th e B ritis h M useum (N at. H ist.).

beds an d th e b asem ent gneiss, th e low est bed being a coarse conglom erate containing large boulders of gneiss. T he succession is as follows :—

K 8 M an d a B eds. P in k fe ls p a th ic sa n d sto n e s 440 ft. a n d m arls w ith one bone b e d ; also c o n ta in s U nio spp.

a n d R hexoxylon tetrapteri­

doides.

K 7 K in g o ri S an d - C oarse, c u rre n t-b e d d e d stones. g rits a n d sa n d s to n e s con- 1,200 ft. g lo m e ratic in p a r t.

--- L o ca l d is c o n f o r m ity --- K 6 L o w er B o n e B ed G reen ish a n d g rey m ud-

300 ft. [stones, lim e sto n e n o d u les a n d sa n d sto n e s, w ith r e p tilia n b o n es a n d fossil (wood a n d tre e s (D adoxylon).

--- L ocal d is c o n f o r m ity --- K 5 [R u h u h u B eds. F in e -g ra in e d g re en ish sand-

700-1,000 ft. stories a n d silt-s to n e s, m u d ­ sto n es a n d sh ales calcareous th ro u g h o u t, w ith m ag n esian lim esto n e b ed s a n d n o d u le s ; o cca sio n al fossil w ood

(.D a doxylon) ; c o n ta in s P a la o m u te la keyserlingi a n d Glossopteris frag m en ts in th e u p p e r beds.

G rey c lay -sh ales w ith coal seam s iro n sto n e s an d sa n d sto n e s.

C oarse g r i tt y san d sto n e s a n d m a r l s ; g re en ish or re d d ish , a n d u s u a lly one lim e sto n e s tr a tu m .

G r itty sa n d sto n e s w ith coal seam s, carb o n a ce o u s shales a n d iro n sto n es .

K1 /B asal S an d sto n e s T h e p a ssa g e b e d is a a n d Con- c h a ra c te ris tic in d u ra te d [glom erate. s p lin te ry shale.

1,690 ft.

T o ta l th ic k n e ss 5,865 ft.

K4 U p p e r Coal

‘M easures.

1335 ft.

K 3 [In term ed ia te . M arls a n d S an d sto n es.

[450 ft.

K 2 L ow er Coal M easures.

450 ft.

Fi g. 6 . — Th e 5 f t. Se a m, Mt a m b a l a l a Ri v e r, So u t h Ma n d a Co a l f i e l d.

N.N.W . ; th ey are chiefly represented by straig h t lines ; consequently th e m ap (Fig. 1) appears like a jig-saw puzzle. The west faults are older, th e north-w est and northerly faults are younger. The whole of th e area is alm ost surrounded by these straight-lined faults w ith large downthrows. One fault has a dow nthrow of a t least 10,000 ft.

The faulting 1 is norm al and vertical and is due to th e sinking of blocks of stra ta , the relative displacem ent of which is irregular.

V ertical walls of gneiss were observed w ith K arroo rocks a b u ttin g against them ; this is illu strated in th e photograph (Fig. 2) where a w aterfall tum bles over a wall of gneiss some 50 ft. high an d the M anda Beds are seen outcropping a t th e base of th e wall, dipping dow nstream . They also outcrop on the fault face, although th e y are not very distinctly seen, behind th e trees. Dragging of s tr a ta down th e fault face was observed ; in some cases th e drag has been downw ards and th e dip is aw ay from th e fau lt face of th e gneiss. In other cases th e beds have been pulled down in th e direction of dip a n d down th e fault plane. In all th e innum erable sections of the K arroo rocks observed in th e rivers and stream s close to th e fault not one instance of folding was observed. All th e faults are norm al and th e tectonics therefore support th e view of tensional strain in th e

1 V ide F igs. 7-11.

w ith th e Ecca. This corresponds exactly w ith th e S outhern R hodesia Series from the E scarp m en t G rits down to th e Lower W ankie Sandstones. The rest of th e U pper K arroo in T anganyika is found in the Kigoma area, n o rth -ea st of Lake T a n ­ ganyika, w here b o th Dr. E. O. Teale, D irector of th e Geological Survey, and P. F ourm arier have shown th a t there are stra ta described as R ed Beds an d overlying lavas believed to belong to the K arroo Period. These s tr a ta m a y be Jurassic.

This probability of a continuous series in th e K arroo extending in to Middle Mesozoic corresponds w ith th e long range of th e Gondwana System of In d ia , which includes rocks from th e U pper Carboniferous to the Jurassic. T here is, however, a suggestion th a t there is an overlap of Ju rassic m arine sedim ents on to th e K arroo in th e coastal area, since no continuous series has been proved. In th e upperm ost p o rtion of th e Tanga Series th ere is a g reat thickness of sandstones which probably belong to the upperm ost K arroo, an d Jurassic beds are apparently faulted against them .

T e c t o n i c s . —

The general tectonics of the area are closely connected w ith th e earliest R ift m ovem ents and app ear to be prior to the N yasan faulting. The m ain directions vary from N .E ., N .N .E ., through N., to

Fi g. 5 . — Th e Bu r n i n g Co a l Se a m, Mh u m b i, Ke t e w a k a- Mc h u c h u m a Co a l f i e l d.

GENERALIZED SECTIONS O f

UPPER COAL MEASURES

S M A N D A C 0 D L /7 E LD K E T E V M K A

HWSALO A/GAKA N D E M B E HCHUCHUMA

F l r COALFIELD COALFIELD CO A t F/ELD.

Fi g. 7 .

rocks of this region to account for the dislocation of th e blocks. In th e Rufiji area, 240 miles to th e north-east of the R u h u h u coalfields and possibly an extension of them , overfolding has been observed.

F o r instance Mennell asserts “ U pstream th e chief features of in tere st are th e faults an d th ru sts a n d th e sandstone ‘ dykes Dr. E. Parsons also reports th ru sts in the h in te rlan d of Mombasa, th e K enya so u th ­ eastern coastal area. The sandstone dykes of th e R ufiji p o in t to tensional m ovem ent, which ap p are n tly followed th e com pressional

m ovem ent. I t is ap p a re n t th a t a g reat deal of th e com pressional phenom ena so observed m ay be explained as local over­

tu rn in g consequent on th e wedging of sedi­

m ents after block faulting.

I t is unlikely th a t an y orogenic m ovem ent can have affected th e K arroo rocks, for no evidence of com pressional m ovem ent local or otherw ise was noted. T he hypothesis th a t forces a t d e p th have resulted in a vertical u p th ru s t m ovem ent is consistent w ith th e features observed in th is region.

U pw ard m ovem ent is necessary to provide th e conditions of real or ap p a re n t sinking of th e blocks an d norm al faulting is characteristic of m an y of th e K arroo areas in E a st C entral Africa. I t appears therefore th a t differential m ovem ents, w hich have affected th e K arroo rocks an d resulted in block displacem ent in th is region, induced tensional results in th a t po rtio n of the upper cru st com posed here of K arroo sedim ents.

H i s t o r i c a l G e o l o g y .

—T he sequence of events is as follows :—

(a) P eneplanation ;

(b) w arping an d sed im en tatio n ; (c) u plift a n d erosion ;

(d) rift valley faulting, an d (e) recent erosion.

The to p ography to th e n o rth a n d so u th of the depression shows th a t previous to the deposition of th e K arro o th e ancient topography was flat a n d was subsequently w arped down, form ing a shallow depression in which th e K arroo lacu strin e sedim ents were deposited. D eposition com m enced in U pper C arboniferous tim es a n d continued to the U pper Trias. A round th is lake and in th e shallow w aters reptiles abounded and th e p ictu re suggests a large, som ew hat shallow, lake, w ith ta ll reeds a n d horsetails and bordered b y forests. T he carbonized rem ains exh ib ited in m uch of th e coal indicate a flora of th e reed ty p e, b u t as fossil trees an d fragm ents of fossilized trees are found in various horizons of th e overlying sedim ents it is probable th a t d rift m aterial helped in th e form ation of th e coal. Dr.

Cyril F ox (Vol. lviii, Geol. Survey of In d ia , 1931, “ The G ondw ana System a n d R elated F o rm atio n s,” p. 14) considers th a t a dam p to w et tem p erate clim ate was b est su ited to th e Glossopteris flora.

Subsequently to th e accum ulation of coal,

conditions of lake sed im en tatio n were

continued, w ith altern atio n s in th e deposition