Annual Report of the

Geological Survey Department

For the year ended 31st December, 1959

A. INTRODUCTION

During 1959 the Geological Survey was in the last financial year of a 4-year development programme. During this 4-year period provision was made for expansion in the establishment of the Geological Survey and this has con­,Iderably increased the range of the Department's activities. This development period ends on March 31st, 1960. The past year has largely been a period of consolidation and re-organization to ensure that maximum benefit is gained from the expansion made possible in the earlier years of the scheme. Estimates for a new 4-year development period have been submitted to continue Geolo­w,ieal Survey in the Bechuanaland Protectorate to 31st March, 1964.

The Geological Survey Department of the Bechuanaland Protectorate has lis headquarters at Lobatsi in the south-eastern portion of the Territory and I hese are provided with a mineralogical and chemical laboratory, drawing office l'neilities, a library and a small museum. The Geological Survey, which was eslablished on 1st April, 1948, has been financed throughout its life by grants made under the Colonial Development and Welfare Act. During the 1956-60 development period the Territorial estimates have been making a local contri­hut ion towards the recurrent expenditure of the Geological Survey and during Ihe financial year 1st April, 1959, to the 31st March, 1960, this contribution from the local funds has been at the rate of 50 % of the recurrent expenses. In I he new estimates which have been put forward for the next 4-year development period, the local contribution will be increased to 75 % of the recurrent expendi­lure during the financial year 1960/61 and will be at the rate of 100% of the recurrent expenses in the second and succeeding years of the 4-year scheme. Ca rital expenditure will continue to be borne by grants from the Colonial Development and Welfare Fund. In this manner the Geological Survey has heen graduating from a totally grant-aided scheme to a Territorial responsibility.

Geological Survey work is directed along three main lines. These are: (11) geological mapping of the exposed areas in the Territory, (b) mineral survey which includes field and laboratory examination of mineral deposits, the survey of' the potential coal resources of the Protectoratc, assistance to operating mines lIud furthering the interest of mining and prospecting organisations in the mineral potential of the Territory, and (c) the development of underground Wilier supplies. The Department employs geophysical prospecting techniques In mineral exploration and hydrogeological work and owns three core drilling machines which are normally engaged on mineral survey. The Geological Survey Illso controls the Government Drilling Branch and is thus responsible for all (;overnment water borehole drilling throughout the Territory, whether by contract or by Departmental methods.

Summary of the Year's Work

During 1959 the staff position showed an improvement over previous years IIl1d this has allowed increased attention to be paid to regional reconnaissance geological mapping. Mineral exploration and development work has been con­i1l1cd to the continued investigation of the potential coalfield areas of the I'rnlcctorate. Assistance has also been rendered to operating mines. Considerable nllenlion has also been paid to underground water development work both in connection with contract drilling and departmental programmes.

During 1959 a total area of some 3,000 square miles was mapped by four Hl~oJogists during the course of the systematic quarter-degree square, reconnaj~-

(d) A Crown Grant was awarded to a private individual for manganese rights on a yearly basis for a period of up to 5 years over an area of the southern Crown Lands. This grant was awarded too late in the year to allow any exploration work to be undertaken during 1959.

(e) A number of short term Crown Grants were issued to private indivi­duals for prospecting rights for diamonds over restricted areas of the southern Crown Lands.

The year 1960 should therefore see increased prospecting activity in different IIreas of the Protectorate and this may well lead to the discovery of important lIlineral occurrences as large portions of these areas kve not been prospected by modern scientific methods.

In addition to these awards negotiations continued on an application for a Crown Grant for prospecting rights over a large area of the Batawana Reserve. t\ n application has also been reccived for the issue of a Crown Grant for dillmond prospecting rights over a large area of the northcrn, central and Ilouthern Crown Lands, and interest has been expressed in obtaining diamond jlrospecting rights over the five major reserve areas in the south-eastern Pro­kclorate. The Anglo-American Corporation of South Africa, as technical IIdvisers to De Beers Consolidated Mines Limited, continued prospecting o"erations in the Lobatsi farming block area of the Protectorate throughout 1959. The Company completed its exploration work in the Gaberones fanning hlock area early in the year. The mineral rights in these farming blocks are oWlled by the British South Africa Company.

From the 1st April, 1959, the Geological Survey assumed full control over 1111 activities of the Drilling Branch, which prior to this fell under the Public Works Department. In addition to Departmental drilling, contract work is ,""Tied out whenever funds allow it. The Geological Survey is now responsible j()[. all Government water borehole drilling in the Territory and its role in IIl1derground water development is the siting and drilling of boreholes to the "1lIge where productive boreholes can be passed to the Public Works Depart­lIlellt who will continue to be responsible for equipping and maintenance of ]lllmping plants.

The Department continued to be responsible for site selection and field control of the Territorial contract drilling programme in the eastern Protec­lorate. This programme was completed in May and since September, 1956, when drilling first commenced, a total of 65,477 feet was completed in 238 bore­holes in the four major eastern Reserve areas. Of these, 166 boreholes were lI11ccessful representing an overall success ratio of 70 %. A limited contract was let for drilling in the south-central Kalahari area and another contract was completed in Ngamiland in the nortb-western part of the Protectorate. The (ieological Survey also undertook siting for all Government drilling rigs and dllring the year 126 boreholes were drilled on sites selected by officers of the neological Survey. Of these 8 were either abandoned due to drilling difficulties or work suspended on them temporarily and of the 118 completed boreholes K'! were successful with a success ratio for all areas in the Territory of 75.5 %.

The Geological Survey Department was represented at the second Annual Congress of the Geological Society of South Africa, held in Pretoria in February, h~ Mr. O . .T. van Straten and Mr. C. M. H . .Tennings. During 1959 the Oeolo-1!.leal Survey collaborated with the Geological Society of South Africa to organize 11 post-Geological Society Congress excursion in the Protectorate, to follow the third Annual Congress of the Society which will be held in Potchefstroom in February, 1960.

III led the professional staff of the Geological Survey will consist of a Director, [It'puty Director, 7 Geologists and a Chemist. One post of geologist is vacant i'ollowing the resignation of Mr. Cullen in July. The post of Laboratory Scienti­lit: Assistant was vacant throughout the year.

The overall establishment of the Geological Survey was increased by Iwdve Division n officers during 1959 consequent upon the transfer of control 01' I he Drilling Branch. The establishment of the Drilling Branch consists of a I>rill Superintendent, an Assistant Drill Superintendent, a Senior Driller and III Drill Foremen and Drillers with ancillary Division III staff. The Drill Super-1lllendent, Mr. A. H. T. Kneen, remained on the strength of the Public Works I kp:lrtment for the financial year 1959/60 and will be transferred to the direct IIonll'ol of the Director of Geological Survey from 1st April, 1960. Throughout Ih" year, however, the Drill Superintendent worked directly under the Director t II' (Jcological Survey supervising Drilling Branch activities.

The strength of the Department on 31st Deeember, 1959, with figures for 111<.\ establishment shown in brackets, was as follows:

Division I

Division n Division III

Geological Survey

7 (9)

8 (9)

49 (68)

Drilling Branch

11 (12)

68 (70)

The classified establishment of the Geological Survey and Drilling Branch, 1I1"llhe Division I and Division Il staff with period of duties served by individual ollkers is shown in Appendix r.

C. FINANCIAL SUMMARY

During 1959 the Geological Survey was in the last financial ycar of the 4-Y"'O' Geological Survey scheme for I 956/60. This was approved in principlc by 1/1<' Secretary of State in 1956 and received a grant from the Colonial Develop-1II"lIt and Welfare Fund D.2894 to covcr expenditurc for thc first two years to 11111 March, 1958. Supplemcntary provision was then made by a grant from ('olonial Development and Welfare Scheme D.2894A to continne Geological NlIl'vey work in the Territory for the final 2-year period until 31st March, 1960. l>"l'ing the financial year 1959/60 the local contribution made by the Bcchuana­IlInt! Protectorate Government towards recurrent expenses has been at the rate or 50 % of the recurrent expenditure.

The development of underground water supplies is financed by Colonial I kvelopment and Welfare Scheme D.2639 which is controlled by the Director Ill' Public Works. During the financial year 1959/60 expenditure for Drilling I1l'1\nch activities within this Scheme is controlled by the Director of Geological NlIl'vey from funds issued on a Departmental Warrant from the Public Works DlIl'lll'tment. In the current financial year the Bechuanaland Protectorate t IIIvernment is making a local contribution of 100% towards recurrent expenses Ill' Ihe Drilling Branch.

A financial statement for expenditure for the year 1st April, 1958, to 31st MlIl'eh, 1959, and the estimated expenditure for the year 1st April, 1959, to 11111 March, 1960, is given in Appendix n.

i I I

I

21

IlI'ohahly form the eastern extension of dolerite sills intrusive into the Karroo ~11'II',a of the South-West Africa artesian basin to the west.

During the course of this survey a visit was paid to the fossil river valley of !11l' Groot Laagte which drains from South-West Africa in a northerly and !Iorlh-easterly direction towards the south-western corner of the Okavango NWIIIllPS and Lake Ngami. About 10 miles south of the Batawana Reserve hOllndary exposures of highly silicified sandstone, which can be correlated with Ih" ilodibeng sandstone (Cave sandstone) present to thc north and north-east, WI\I'O located in the bed of the fossil vallcy. The presence of exposures of the Bod­Ihlmg sandstone in this area indicates the former wide extension of Stormberg M",'I", rocks in this region.

F. WATER SUPPLY

During 1959 the Gcological Survey assumed control ovcr all activities of Ihe Government Drilling Branch. Prior to April 1st, 1959, this Branch was under Ill" control of the Public Works Department and the Geological Survey was IIlIly responsible for site selection and field control of contract and Departmental drilling programmes. The Geological Survey is now responsible for all Govern­IIIl",t water borehole drilling in the Territory, whether by contract or Depart-111I\l1tal methods, and its role in underground water development work is the ",Iection of boreholc sites and the drilling of boreholes to the stage where productive boreholes can be passed to the Public Works Department for equip­plllg and maintenance. The headquarters of the Drilling Branch are at 1Il1ilerones, some 50 miles to the north of Lobatsi.

During 1959 the Department continued to be responsible for site selection fllr the 1955/60 Underground Water Development Scheme which is financed by e<llollial Development and Welfare Fund Scheme D.2639. Under this scheme a IIIIIJor contract drilling programme has been in progress in the eastern Protec-1!.1I'lIle. This was compleled in May. From September, 1956, when contract lirllling started, until May, 1959, a total of 65,477 feet was drilled in 238 bore­holes of which 166 were successful. This represents an overall success ratio of 111%, The bOleholes were distributed as follows:

Reserve Area Bakwena Bangwaketse Bakgatla Bamallgwato

No. of bortho!es

67 63 48 60

No. of successful boreho!es

48 42 27 49

Footage drilled 19,468 16,107 12,373 17,529

A limited contract was let for drilling in the central Kalahari area in the 1I'1'.\lern portions of the Bangwaketse and Bakwena Reserves. The test drilling programme in Ngamiland was completed in April. Geophysical surveys were n,rricd out in the Ghanzi district and test borehole sites selected in connection II'lIh the projected expansion of the Ghanzi farming block. Assistance has also 1I('l'n rendered to townships and villages, and to the cattle export route drilling ill the central Kalahari. A number of boreholes were also selected for private Individuals in the fanning blocks.

IiAKGATLA RESERVE

The water development programme in the Bakgatla Reserve was completed I" M arch. A total of 12,373 feet was drilled in 48 boreholes of which 27 were "1Il'ccssful. Four of these boreholes (one successful) were dr;lled in 1957 and the

22

remainder were drilled on sites selected by Mr. Wilson in 1958. Thirty-five boreholes were completed in 1958 and of the 9 boreholes completed in 1959 seven were successful. The majority of tbe boreholes were drilled for village supply and agricultural purposes. Many of tbe sites had to be selected in area, underlain by younger granites or felsites of the Dominion Reef System which arc notoriously poor groundwater bearing formations. A statistical summary of the drilling carried out in the implementation of the water development scheme in the Bakgatla Reserve is as follows:

Total numher of boreholes drilled Number of successful boreholes Success ratio Total footage drilled Footage of successful boreholcs Average depth of borcholes Average depth of successful boreholes Total tested potential yield of borellOles Average yield of successful boreholes

BAMANGWATO RESERVE

48 27 56%

12,373 feet. 6,760 feel.

257 feet. 250 feet.

] 6,6]0 g.p.h. 6] 5 g.p.h.

The programme in the Bamangv.,rato Reserve was completed in May. Site selection in this arca was carried out by Mr. C. M. H. Jennings. A total of 17,529 feet was drilled in 60 boreholes of whicb 49 were successful. Thirty four of these boreholes were completed in 1958 and of the 26 boreholes drilled during 1959 twenty one were successful representing a success ratio of 81 %. The boreho1es drilled during 1959 were all for village supply and agrieuJturallands purposes ill the central Reserve area. The sites were selected in areas underlain by Karroo System sedimcnts and lavas, sedimcnts of uncertain Waterberg-Loskop System age, in areas underlain by sedimcnts belonging to the Shushong Series with associated intrusive doleritcs, and in areas underlain by rocks of the Basement Complex. A statistical summary of the drilling carried out ill the implementation of the water development scheme in the Bamangwato Reserve is as follows:

Total number of boreholes drilled 60 Number of successful borehales 49 Success ratio 81.7% Total footage drilled.. 17,529 feet. Footage of successful boreholes 14,510 feet. Average depth of boreholes 292 feet. Average depth of successful borcholes 297 feet. Total tested potential yield of boreholcs 40,220 g.p.h. Average yield of successful boreholes 820 g.p.h.

SourH-cENTRAL KALAIIARI AREA

Mr. C. M. H. Jcnnillgs undertook site selection in the Kalahari area of the western Ihlkwcn<l and Bangvo/aketse Reserves for a limited contract drillingpro~ gr~llllll1C which was completed between June and August. An aerial reconnais~ sallcc survey orthe area, which is not covered by acrial photography, was carried out in May as a preliminary 10 the ground survey work. The area in which the drilling was carried out is mainly underlain by sediments of the Karroo System beneath thick cover of recent Kalahari Beds. On the southern margin of the Karroo basin isolated exposures of the prc~Karroo Matsap Beds arC present but the area of exposures is restricted. Ten boreholes were drilled in this area and of these 7 were successful and three yielded highly saline supplies. The total dissolved solids contents of the successful boreholes ranges up to 6,500 p.p.m. In this central Kalahari region a salinity of 10,000 p.p.m., depending upon the

23

Ikll11position of the groundwater, is regarded as the upper limit of the potability :tllUgc for stock. In certain parts of the region groundwaters with a salinity in I!KCess of 10,000 p.p.m. are used by both humans and stock. Only one of these

'btl.l'choles was sited on pre-Karroo rocks and the remainder derive their ground­\\'lIlers from aquifers in the Middle Ecca Series of the Karroo System. The source

':.~l'rccharge of these aquifers is not known and is being investigated at the present ':llmo.

Surveys in connection with underground water development work were '. Undertaken by the Director and Mr. O. J. van Straten in July in the south­.\\'Oi!crn Crown Lands .

. t'lIlANZI FARMING BLOCK AREA

Following a reconnaissance survey of the north-western Crown Lands and Iho Ghanzi district in February, undertaken by the Director accompanied by M 1'. M. T. J ones and Mr. I. Gerrard, it was recommended that test drilling ,hould be carried out in the Ghanzi district before any more farms were surveyed in connection with the projccted expansion of the farming block. Experience hnl! shown that there is little or no possibility of locating potable supplies in the (')hunzi Beds formation wherever these rocks are blanketed by upwards of 20 /llot of windblown sand of Kalahari type or a thick cover of recent Kalahari l.luds. Experience in Ngamiland to the north-west had shown that considerable dllllculty could also be expected in developing potable supplies even in areas of Qxposure or thin sand cover and it appeared that only restricted areas were IIVlliIable for further expansion of the farming block. Mr. Jones and Mr. (jr,l'rard carried out geophysical surveys in the Ghanzi district in April and iolcctcd test sites to the south of the existing surveyed farming block. Two high­ylolding boreholes were developed in one area where development had been Itlcommended.

NOAMILAND

The Director carried out a survey of western Ngamiland with the Director Ht' Agriculture in November in connection with a water development programme III be implemented there in 1960.

Test drilling in the marginal Hainaveld area in the Batawana Reserve was tli,conlinued in April. During 1959 eight test boreholes were drilled and of Ihtlse only three were successful. One borehole yielded a highly saline supply. In vlt'w of the disappointing results obtained from this test driIIing programme it \\'IIS decided to suspend drilling in this area until further detailed geophysical ~'lrvcys have been carried out.

(IIIANZI CATTLE EXPORT ROUTE

In the Ghanzi cattle export route drilling programme a high yielding bore­Iiole was developed at Mabutsane, 23 miles north-west of Sekhuma pan. The '"l'l'ly was obtained at depth in quartzites correlated with the Matsap Beds. Ihe lotal dissolved solids content of this groundwater is only 474 p.p.m. and Illis ranks as one of the best quality waters so far obtained in this south-central ""lailari region. A second potable supply was developed for the cattle export !llIllc some 30 miles to the east of Mabutsane and 6 miles north-east of Sekhuma 1'"". The aquifer in this area is also an horizon in the Matsap Beds quartzites IIl1d here the total dissolved solids content of the groundwater is only 150 p.p.m. AI lile end of the year test drilling was in progress 35 miles north-west of Kang III 1111 attempt to bridge the long waterless stretch from Lone Tree pan south to 1\ IIl1g.

24

TOWNSHIP SUPPLIES

In connection with township supplies further test drilling was carried out on the farm Woodlands, north-east of Lobatsi. This work was suspended temporarily during the second half of the year and the drilling rig was moved to Gaberones. A number of sites had been selected here by Mr. P. T. Wilson to augment the failing township supply. The main aquifers being tapped at Gaberones are gravels in the Notwani River floodplain which are dependent for recharge on annual flooding of the river. No flooding took place during the 1958/59 rainy season and gradual depletion of the aquifers is taking place. A number of high yielding barehales were developed but these were also showing reduced yields by the end of 1959 and it became obvious that the township would have to rely on additional SOurces of supply from the Notwani Dam which was built during the year. The Gaberones area is underlain by a tightly jointed, younger granite which has little or no depth of decomposition and only very low yielding boreholes can be cxpected in this formation.

A tabulated list of boreholes drilled on sites selected by officers of the Geological Survey is shown in Appendix IV. A total of 126 boreholes were drilled on sites selected by the Geological Survey during 1959. Of these 8 were abandoned or suspended temporarily and of the 118 completed boreholes 89 were successful represcnting an overall success ratio of 75.5 %. Of the 29 blank boreholes 7 yielded saline supplies.

DRILLING BRANCH ACTIVI'I'IES

Of the 120 boreholes drillcd by Government during 1959, 50 were completed by contract and 70 by Departmental drilling. The footages drilled were 15,000 and 18,464 feet respectively.

The Drill Superintendent, Mr. A. H. T. Kneen, was absent on overseas leave from May until November and during his absence the activities of the Drilling Branch were controlled by the Assistant Drill Superintendent, Mr. E. M. F. Owen. For Illost of 1959 only g Government drilling rigs were manned. No attempts were made to recruit Drill/Foremen for the two vacancies in the establishment owing to the chronic state of the Branch's transpon. Five new Bedford 5-ton diesel trucks were purchased during the year which considerably eased the transport position and one of the vacant posts of Drill/Foreman was filled at the end of November. Applications were being considered for the remaining vacant post at the end of the year.

Government operated rigs completed a total of70 boreholes (49 successful) du,ing 1959 as against 49 bOlcholes (33 successful) during 1958. In addition 7 boreholes wcre clean cd or deepened. The majority of these were drilled in the remote arcas of the Protectorate and a number of the rigs were occupied with test drilling. When it is rememhered that the section was short-staffed and laboured undeI' transport difficulties the progress is very satisfactory indeed. Transport difficulties caused numerous drilling delays particularly during the first six months of the period. In addition seven of the rigs are in need of replacement engines. These have been estimated for in the 1960/61 financial year and are an urgent requirement if the efficiency of the Drilling Branch is to be maintained.

Following the transfer of the Branch to the Geological Survey in April a new store and stores yard were erected at Gaberones.

Thc statistical rcsuHs of the work completed by the Drilling Branch during 1959 are tabulated in Appendix Ill.

In addition 9 tracings of various geological maps and other plans were prepared and 475 maps and plans, both hachured and hand coloured, printed in the drawing office. Assistance was rendered to other Govern­ment Departments as follows:

(a) Secretariat: Topographical map of the Bechuanaland Protec-

torate .. 1 :1,000,000 (This map was printed to a scale of I :2,000,000 and issued with the Annual Territorial Report for 1958.)

(b) Public Works Department Road Map of the Bechuanaland Protectorate I: 1,000,000

(d) Reports and Publications

The Annual Report for 1958 was sent to the printers in October but printing ,h'IIIY' were experienced and it will only prove possible to issue the published H"port in the first quarter of 1960. The Annual Report for 1957, the Records of lit" Geological Survey for 1956, and a Mineral Resources Report No. I on the "Morapule Coalfield, Palapye Area", prepared by Mr. O. J. van Straten, were ill!>iI'ibuted during the year. The Records of the Geological Survey for 1957/58 I,"v" been prepared but available funds will only allow publication in the II11Hllcial year 1960/61.

The undermentioned reports were prepared:

iI y C. BOOCOCK:

Annual Report of the Geological Survey Department for the year ended 31st December, 1958.

Mining in Bechuanaland (prepared for the Annual Colonial Report). Report on the Progress of the Colonial Development and Welfare Scheme

D.2894, Geological Survey, for the year ending 31st December, 1958. Mineral Resources of the Bechuanaland Protectorate (to be published in the

Overseas Geology and Mineral Resources). The Geology and Hydro-geology of the Central Kalahari Region, Bechu­

analand Protectorate (paperpreparedjointly with Mr. O. J. van Straten). Annexure to His Honour's Address to the 62nd Session of the European

Advisory Council. Progress Report for the Half-year Ending 30th June, 1959. Report for the Advisory Committee on Overseas Geology and Mineral

Resources 1959. Note on the Water Development Scheme in the Bamangwato Reserve. Note on the Mineral Potential and Mining Position in the Tati Concession. A Note on the Role of the Geological Survey Department of the Bechuana-

land Protectorate in Relation to the Development of the Underground Water Resources of the Territory.

fly O. J. VAN STRATEN:

The Morapule Coalfield, Palapye Area (issued as Mineral Resources Report No. 1 of the Geological Survey Department).

Notes to accompany a Provisional Soils Map of the Bechuanaland Pro­tectorate.

The Geology and Hydro-geology of the Central Kalahari Region, Beehuanaland Protectorate (paper prepared jointly with Mr. C. Boocock).

Report on Aerial Reconnaissance of the Southern Kalahari. Woodlands Water Supply Project. The possibility of pollution of ground­

water supplies.

By D. GREEN;

A Further Examination of Some Dwyka Pebbles from the Core of Bore hole B.16.

Report on the Examination of Drill Cores from Boreholes at Moshanc!l) Mine.

By D. 1. CULLEN:

The Shushong Series and Associated Intrusivcs. The Geology of the MolepoloJe Area. A Note on the Distribution of Waterberg and Loskop Formations ill

Southern Bcchuanalancl Protectorate.

By P. T. W,LSON:

Report on a Borchole Site for Police Post at Sequani. Suggested Improved Water Supply [or Phaphane Camp ··-Mochudi. Report on Borcholc Sites near Molopo Rivcr·---·Bangwakctsc Reserve. Report on Underground Water Prospects in the Kika Concession Arca. Underground Water Development Schemc-----Kgatlcng District. Report 011 Water Boreholc Sites, Kukong-~Bangwaketse Reserve. Report on Water Borehole Sitcs---·-Kgwakgwe Manganese Mine. Report on Emergency Borehole Sites--Gaberones. Report on the Ootse Manganese Occurrences. Supplementary Report on the Ootse Manganese Workings. Report on the Radioactivity of the 00ts0 Manganese Ores.

By C. M. H. JENNINGS:

Report Oil l3oreholc Sites for the New Secondary School at Ootse, Bamak'l{' Reserve.

Report on Grolllldwater Investigations for N.R.C. Khale. Hydrological Survey at Pitsanc. Report on Drilling Programme carried out by Contract in the Bamangw<l(o

Reserve, 1958 and 1959. Report on 13orehole Sites for proposed Police Border Post in Ramaquab'lllt'

River. Short Report on Groundwater possibilities at Moeng College. Report on Boreholcs sited in the Seruli area----Bamangwato Reserve.

By M. 1'. 10NES;

A Report on the Ciroundwatcr Investigations on the farm Woodlands. Lobatsi (prepared ill collaboration Ivith Nlr. I. (j'r!/'rard).

A Report on Test Sites to be drilled in the Ghanzi District (prepared ill collaboratioll with Mr. I.Gerrard).

The Geology of the Area to the East of Gaberones.

By I. GERRARD:

Petrographic DeSCriptions or Specimens Collected on Tati River, Francis­town District.

A Report on the Groundw{1ter Investigations on the farm Woodlands, Lobatsi (prepared ill collaboration It'i!h .A1r. AI. T. lones).

A Report on Test Sites to be drilled in the Ghanzi District (prepared ill ('o//ohof'{1tioll !l'ith Mr. A1. T. lanes).

A Note 011 Specimens from the Ghanzi Beds, Ghanz\ District, H.P.

Lob:ltsi, 14th April. 1960.

C. BOOCOCK,

Director 0/ C;eological SUI'VeI-'.

~,~,A Pi ,!'!i, q, ,t%,,-, qL~l,JII'",,!r·"')!'!"L .;;1'_,11'. }; [. ,U~~SM,,,. «"~'IU. .•

APPENDIX III

Statistics of Drilling Branch Activities

De:elopment of Underground Water Supplies. Statistics of Drilling carried out Departmentally and by Contract during 1959

Drilling Branch Contract

Area or District No. of Footage drilled * No. of No.of* successful in completed No.of* successful

boreholes boreholes boreholes boreholes boreholes

Batawana Reserve (Ngamiland) .. .. .. .. .. 4 1 635 5 1 Bamangwato Reserve . . . . .. .. .. . . .. 4 4 1,138 26 21 Bakgatla Reserve .. .. .. .. .. .. . . .. 3 2 507 9 7 Bakwena Reserve .. . ' .. .. . . .. . . 7 5 2,156 3 3 Bangwaketse Reserve " .' .. .. .. .. .. 7 I 1,811 5 2 Batlokwa Reserve .......... .. . . .. I I 125 - -Southern Crown Lands (Tsabong district) .. .. .. 8 7 2,355 I I Northern Crown lands (Ghaozi district) .. .. " 13 7 3,276 - -Cattle Export Routes . . . . . . . . .. .. .. 1 1 524 I I Government Townships and Stations .. .. .. . . 23 17 5,315 - -Miscellaneous .. .. . . . . . . .. .. " .. 3 3 622 - -

TOTALS .. .. . . . ' .. .. . . .. 70 49 18,464 50 36 ~ .- _ .. -

.-- - I

*Includes boreholes abandoned or temporarily suspended.

Footage drilled* in completed

boreholes

1,350 7,775 2,218 1,408 1,605

-390 -

354 --

15,100 ~

APPENDIX IV Table of Boreholes

Boreholes drilled on sites selected by officers of the Geological Survey

Offi- Depth Static Water cia! Locality in Yield Depth Water Rest Level Geology No. feet G.P.H. Struck in feet from Surface

in feet

1038 Mochudi, Bakgatla Reserve .. .. 242 90 70, 170, 180 145 Watcrberg System Sandstone (170') and Basement Complex gneiss.

1039 Oodi, Bakgatla Reserve .. .. 100 200 50 35 Gaberones type granite. 1041 Woodlands, Lobatsi Block .. .. .. 500 No test 92 and 117 45 Pretoria Series shale and quartzite (Transvaal

1044 Palapye, Bamangwato Reserve .. .. 220 330 170 29 System).

Lotsani shales (Undifferentiated Waterberg/Los· kop System).

1045 Maroa, Bakgatla Reserve .. 250 Blank 90 51 Gaberones type granite. 1046 Tsabong, Southern Crown Lands .. 306 Blank - - Quartzite (Matsap Beds). 1047 Oodi, Bakgatla Reserve .. .. 80 150 35 30 Gaberones type granite. 1048 Bokaa, Bakgatla Reserve .. .. 300 240 150 60 Gaberones type granite and granophyre. 1049 Serowe, Bamangwato Reserve .. .. 365 1,800 255 101 Basalt (250 ') and Cave sandstone. (Stormberg

Series, Karroo System.) 1050 Palapyc Area, Bamangwato Reserve. _ 350 Blank 20 and 254 230 Ecca Series shales (250 '), Dwyka Series (280 ')

(30 g.p.h.) (Karroo System) and quartzite (Undifferentited Waterberg/Loskop System).

1051 Palapye. Bamangwato Reserve .. .. 480 700 95 14 Lotsani shales (Undifferentiated Waterberg/Loskop System).

1052 Gaberones township " 135 Temporarily abandoned. - Gaberones type granite. 1053 Mamakoro, Bakgatla Reserve .. .. 200 1,500 74, 100, 108, 70 Sandstone and siltstone (Loskop System(?»).

127 and 147 1054 Serowe, Bamangwato Reserve 265 1,200 220 141 Basalt (215 .) and Cave Sandstone (Stormber£

1055\ Mogarosi, Bamangwato Reserve Series, Karrao System).

300 1,000 , 165 and 275 144 \ Basalt (110 ') and Cave Sandstone (Stormber~

1056 \ Serowe. Bamangwato Reserve 300 I \ Series, Karroa System). 191 130 130 Cave Sandstone (140 ') and dolcrite (190 ') (Storm-

1057 \ Palapye Arca, Bamangwato Rcsccve .

, I berg Series, Karroo System).

\ 320 300 I 100 80 Ecc<\ and Thiyka Series (lOO ') (Karroo System) anc ,

quartzite \ UndifTerentiated Waterberg/Loskar. I

"''''' ... n('u, , ,., - -, '" . ~." <:,! R,',-.. ,-- '::~-~'_-'~'~ '3',' '\ 2:-:::'. c::.:~ S:;,:::.:~:C':::~ rS:C':-:7l-

01:5;" ci8 ;-';0.

1059 1060

1061 1062

1063 1064 1065

1066 1067 1068

1069 1070

1071 1072

1073 1074

1075 1076

1077 1078 1079

1080

1081 1082 1083 1084 1085

~ •••.. ~,.,-.,~,,~~-~~-- _r <;;, f _ 'l'-~.. ._~~_.-

'X!,_~~",~~~~_-._~

Lcc2:.:.~

Gaberones township Mmane, Bakgatla Reserve

Moshupatsela, Ngamiland Serowe, Bamangwato Reserve

Maokwe. Bamangwato Reserve .. Malejana Reserve .. Serowe, Bamangwato Reserve

Mmadila, Bamangwato Reserve Gothabala, Bamangwato Reserve Makunda, Ghanzi district

Lerula, Bakgatla Reserve Woodlands, Lobatsi Block

Woodlands, Lobatsi Block Mal ish, Tsabong district, Southern

Crown Lands Mookane, Bamangwato Reserve Makgabana Hills, Ngamiland

Gowa Pan, KgaIagadi District Khong Pan, Bakwena Reserve

Woodlands, Lobatsi Block .. KuIi, Ghanzi District .. Xanagas, Ghanzi District ..

Gogwe Pan, Bakwena Reserve

Mamabule, Bamangwato Res'erve Lerula, Bakgatla Reserve Kgwebe Hills, Ngamiland Makgabana Hills, Ngamiland Kgwebe Hills, Ngamiland ..

feet

114 400

277 300

300 250 323

250 250 151

296 421

200

317 250 200

368 365

400 512 150

440

400 350 400 300 102

Ydi 'i~-W~ G.P.H. f Struck in feet

60

Blank 900

850 1,800

450

850 300

2,400

Blank 3,000

3,000

2,500 1,000

Blank (2,500 for t hour)

350 Saline Supply

4,300 No Test

2,400

200

420 2,000

Blank 120

Saline

abandoned. 300

50 and 256

100, 240, 255 120 and 145

260

65 and 195 115

80 and 94

90

68

211 and 285 135

95 and 115

165 and 350 626

50, 160, 175 439 107

405

140 140 and 240

227 198 99

100

45

58 115 211

50 105 64

50

46

170 83 85

153 385

42 382 82

360

90 97

178 164 80

Gaberones type granite. Shaly sandstone and siItstone (Waterberg Sys­

tem). Quartzite with shaly intercalations (Ghanzi Beds). Basalt (I90') and Cave Sandstone (Stormberg

Series, Karroo System). Ecca Series shales and sandstones (Karroo System). Cave Sandstone (Stormberg Series, Karroo System). Basalt (260') and Cave Sandstone (Stormberg

Series, Karroo System). Ecca Series shales and sandstones (Karroo System). Cave Sandstone (Stormberg Series, Karroo System). Quartzite with shale and siltstone below 140'

(Ghanzi Beds). Dolerite intrusion in Waterberg System. Pretoria Series shale and quartzite (Transvaal

System). Pretoria Series shales (Transvaal System).

Quartzite (Matsap Beds). Ecca Series shales and sandstone (Karroo System). Quartz felspar porphyry (Kwebe Porphyry Series).

Quartzite (Matsap Beds). Recent deposits (120') and upper Ecca Series shale

and siltstone (Karroo System). Pretoria Series shale (Transvaal System). Ecca Series shale and sandstone (Karroo System). Recent deposits (30 ') and sandstone and shale

(Ghanzi Beds). Recent deposits (210 ') and Ecca Series shales and

sandstone (Karroo System). Ecca Series shales and sandstone (Karroo System). Sandstone and siltstone (Waterberg System(?)}. Quartzite and shale (Ghanzi Beds). Quartzite and shale (Ghanzi Beds). Quartzite and shale (Ghanzi Beds).

Offi­cial No.

1086

1087

1088

1089

1090

1091 1092

1093

1094 1095 1096

1097 1098

1099 1100 1101 1102

1103 1104 1105 1106 1107 1108

1109

1110

Locality

Mookane, Bamangwato Reserve ..

Serowe, Bamangwato Reserve

Mabua, Bamangwato Reserve

Pilikwe, Bamangwato Reserve

Kgwebe Hills, Ngamiland ..

Tlokweng, Batlokwa Reserve Ootse, BamaJete Reserve

Palapye Area, Bamangwato Reserve ..

Tebele, Bamangwato Reserve Molepolole, Bakwena Reserve MalalaIeng, Tsabong district, Southern

Crown Lands Makunda, Ghanzi district Malemilode, Bamangwato Reserve

Ootse, Bamalctc Reserve .. Lecheng, Bamangwato Reserve Tsetlo, Bamangwato Reserve Mabutsane, Bangwaketse Reserve

Kalamare, Bamangwato Reserve Serowe, Bamangwato Reserve Molepoiole, Bakwena Rseerve .. Gainaga Valley, Ngamiland Ootse, Bamaletc Reserve .. Pata ya diphuduhudu pan, NgamiJand

North of Buitsivango valley, Ghanzi district ..

Ramoutsa, Bama1cte Reserve

Depth in

feet

250

350

400

350

118

125 200

380

350 390

400 151 250

172 250 250 524

Yield G.P.H.

2,000

75

Blank (40 g.p.h.)

200

Saline Supply

750 1,800

150

Blank 1,200

420 2,400 2,400

1,200 300 200

1,500

250 Blank

Depth Water Struck in feet

70

80 and 130

250 and 360

140,245 and 265

85 and 114

112 80 and 100

230

360

275 and 380 94

145

83 and 105 120 and 210

150 295,506 and

512

86 Borehole abandoned. 300 60 53 138 240 126 250 300 80 and 200 400 Blank

135 I Boreholel abandoned. 121 1,200 80

Static Water Rest Level

from Surface in feet

50

70

235

156

65

45 65

180

70

250 59

130

66 74

134 280

25 118 60

46

Geology

Ecca Series siltstone (40,) (Karroo System) and syenite.

Cave sandstone (40') ,dolerite (190') and Cave Sandstone (Stormberg Series, Karroo System).

Ecca Series shale (185') (Karroo System), syenodio­rite (335 ') and pink granite (Basement Complex).

Recent deposits (20 ') and Basement Complex granitic gneiss.

Quartzite (Ghanzi Beds).

Gaberones type granite. Red shale (180 '), sandstone (190 ') and red shale

(Waterberg System(?» Ecca Series shale (130') (Karroo System) and

granite. Ecca Series shales and sandstone (Karroo System). Dolerite.

Quartzite (Matsap Beds). Quartzite (Ghanzi Beds). Cave Sandstone (901, Red Beds (2201 (Karroo

System) and dolerite. Shales (Waterberg System). Quartzite sandstone (Loskop System(?». Ecca Series shales and sandstone (Karroo System). Quartzite and shale (Matsap Beds).

Granite, decomposed to 130 I (Basement Complex). Diabase. Shale (Waterberg System). Quartzite (Ghanzi Beds). Sandstone and conglomerate (Waterberg System). Recent deposits (130') and quartzite and shale

(Ghanzi Beds).

Quartzite (Ghanzi Beds). Mogobane Series shales and siltstone (Ventersdorp

System).

QE­cial No.

1111

1112

1113 1114

1115

1116

1117

1118

1119

1120

1121

1122

1123

1124 1125 1126

1127 1128

1129

L=jj"

Logaganeng, Tsabong district, Southern Crown Lands

Woodlands, Lobatsi Block ..

Khekhe valley) Southern Crown Lands Fox pan, Bangwaketse Reserve

T.T.C. Lobatsi Block

KamaIane Pan, Crown Lands

West of Metokwe, Bakwena Reserve ..

Motsobonye Pan, Bangwaketse Reserve

Fox Pan, Bangwaketse Reserve ..

North-west of Metokwe, Bakwena Reserve

Molepolole, Bakwena Reserve .'

Pitsakgolo Pan, Bangwaketse Reserve

Muruti wa Thutla Pan, Bangwaketse Reserve

Groot Laagte, Ghanzi district Groot Laagte, Ghanzi district Woodlands, Lobatsi Block ..

T.T.C., Lobatsi Block.. .. North-east of Metokwe, Bakwena

Reserve

South of Buitsvango Valley, Ghanzi district.

'n:dtl feet

185 350

210 234

204

390

431

315

450

478

160

301

386

80 296 300

300

490

300

W 11(-- --~-~::- ~

} ·1'--' rdd G.P.H.

De;l<h ~ R= r.e-. .. Struck in feet from Swface

in feet

400 145 1,600 74

100 204 Borehole abandoned.

600 85, 100 and 140

350 370

200 400 and 426

Saline 300 Supply Saline 300 and 440 Supply

900

600

Saline Supply

Saline Supply Boreho1e Blank

2,400

Blank

360

Blank

417

50, 105 and 130 296

381

abandoned.

110 and 150

420

170 and 281

120 50

200

71

327

374

278

300

400

45

257

345

103

385

242

~

Quartzite (Matsap Beds). Pretoria Series shale and quartzite (Transvaal

System). Quartzite (Matsap Beds). Recent deposits (200 ') and Cave Sandstone (Storm­

berg Series, Karroo System). Mudstones and shales (50 ') and dolomite (Dolomite

Series, Transvaal System). Recent deposits (160 ') and Ecca Series (Karroo

System). Recent deposits (210,), Cave Sandstone (370 ')

(Stormberg Series) and Ecca Series (Karroo System).

Recent deposits (130 ') and Ecca Series (Karroo System).

Recent deposits (200,), Cave Sandstone (Stormberg Series) (240') and Ecca Series (Karroo System).

Recent deposits (210 '). Cave Sandstone (Stormberg Series) (360') and Ecca Series (Karroo System).

Sandstone (Waterberg System).

Recent deposits (290') and &ca Series (Karroo System).

Recent deposits (340') and Ecca Series.

Quartzite and shales (Ghanzi Beds). Quartzite and shales (Ghanzi Beds). Quartzite, shale and siltstone (pretoria Series,

Karroo System). Shale (Transvaal System).

Recent deposits (250 ') Cave Sandstone (Stormberg Series) (290') and Ecca Series (Karroo System).

Recent deposits (50') and quartzite and siItstone (Gbanzi Beds).

'" "

Offi­cial No.

Locality Depth

in feet

Yield G.P.H.

Static Water Depth Water I Rest Level Struck in feet ! froill Surface

I i'1 feet I .

)\;ortl'l-east of Sekhuma Pan:B<lngw~~!~~-~I~~ - I-~- -~- - -1 200 I )46 I 287

] 130

J 13]

1132 11)1

1134 1135

K<?lSe Res;':n"c \Yoodlands. lobalsi Block

~~;~~~-.;~~~~~ \.Gj~~i~;'~:"~. B,: ngwaketse R,.;scn·c

Gabcroncs. (own"h:o M~.l~!;:csdtjfL T,:ii Bicy.:k

1; 36 ! \Voc-di:l,'(s. ~_c-::.,;: ", ·,:OC~

1 J 37

J138 j 139 114()

Nonh oC i3\:j:,,:\",~,.:~p \'~;!ky. Ghanl.! district

i,~r!~~~~:~ ?,'<G, f~" ?;;.' ;\ ~ . ..'\"')": R.~>~ ;r\'(:

!i41 re 1\42

R.cs~r\·'('

1143 1144 1 14-5 1146 1147 1148 ]]49 1150 t 152

Khckc V'ilky. Sr:i.l!h~!"n C··:;1'.·T\ Lnnds r'·:~.oh:i:·():ol". B;\:<\";~:'~t h~S(. -vc G;,bzroncs to\v:i-ship OJir;~;,rs D:-ift, B;-dq;,:t!la Reserve j( ukong, B,mg,vak.::tse Res:.::rve G"beroi1~s township Sequani, Bakgatla Reserve North of Bui!svango Valley, Ghanz:

district

! 153 I North of Sekhuma Pan, Bangwaketse Reserve

1154 Gaberones township 1 [55 Scruli, Bamangwato Reserve 1156 Gaberones post office 1157 Serll1i ,'<1"<::<\, Bam<.li:gwcllo Res(;f\'c

354 103

235

500

300 94

404·

20} 220 In;; ~-;L,O

i24 "7 0,

119 2() j

35D 100

BO 120 7,

u

144

262

323

200 165 400 250 ,

Borehok: .(empor'l.l,h ab<l;ndoned

Blank

360

250 2,8(;0

450

],600 Bhl:ik

100 200

Blank 200

B.1a!lk 80

! 10 1,500

600 Blank

Borehol·-.:: Blank

2,000

Blank

675 1,400

80 : .C5U

356

60 60 and 9/,

12S

112

55 305

IY)

SO

i

326

50 40

i20

158

50 300

iOO 40

lq<; ISO 45 and 165 40

6:-; ~,S

60 20 l20 90

icmporarily ablandoncd.

177 and 196

56 and 163 ill, i37, 14i

250

159

50 84

220 ;::: L j;;':5 ;{;"; j \.",9

Geology

QlIartz~te (Matsap Beds(?) ). Sil!5:0118 and qu::rtzite (Pretoria Series, Transvaal

Sys!crn). Recent (kposits {50 '). and siltstone (Ghanzi Beds).

Recent deposits (160 ') Cave Sandstone (Storm­b2r:.; $::;ries) (130 ') ?nd C;l:arr7.i~;::s (M"tts:::p Beds).

Gabcro::-;c3 ;ypc gr,1!1ite and dole, j!c. :'~ln·:~!~ CO~l"\;"'.lcx

Sij~~:,; ~:~'::.1' 1 ·S~;.~:~,,~~.;ot qU,~i ,/1,<: s~~: ,·:s,

RCC'::1: (Ch':::rzi i3cd:-.). )-=:;:1:,::t,: {Do:;-;;::!~'~:'

F:~h(,,'

~~2, :~;s n. ~;~TOG'

R.(:,~f Syskm) and dol,c(·i1.c. C);:;b..:rc:ncs :yp~ l:r~,;:i:c" Di;11x:::-;c.

i.;nd do1cri!C. 1060 '.

- S;i:'itcm) nnd dolcritc.

Recent deposits (80 ') and quartzite and shale (Ghanzi Beds).

Recent deposits (230 '), quartzite (Matsap Beds) (250 ') and dolcrite.

Gaberones type granite and doleritc, Quartz-scricitc schists (Basement Complex). Gaherones (vac granite. b:.·..::·~: S,;r,e:, r'r:.:"r~·0o ::-".Slo.':'

Offi- Depth Static Water cial Locality in Yield Depth Water Rest Level Geology No. feet G.P.H. Struck in feet from Surface

in feet

1158 Sequani, Bakgatla Reserve .. .. 230 480 120 and 196 110 Basic lava (Ventersdorp System). 1159 Gaberones township .. .. .. .. 200 540 80 and 150 43 Gaberones type granite . .

Privat e Boreholes: . Ootse, Bamalctc Reserve .. .. 276 Blank 170 160 Sandstone and shale (Mogobanc Series). Francistown, Tati Concession .. .. 80 240 60 40 Granite, decomposed to 60' (Basement Complex). Francistown, Tati Concession .. .. 74 1,500 53 25 Decomposed granite (Basement Complex). Francistown, Tati Concession .. .. - 600 - - Doierite, decomposed to 80 '. Sunnyside, Lobatsi Block .. .. - - - - Waterberg System sediments. Kanye, Baog\'i'aketse Reserve .. .. - - - - Gaberones type granite and dolerite. Kanye, Bangwaketse Reserve .. .. - - - - Cheft breccia. Kanye, Bangwaketse Reserve " .. 280 2,500 180 and on 176 Chert breccia. --_._ ....