ANNUAL REPORT

of the

GEOI .. OGICAL SURVEY DEPART~IENT

For the year ended 31st December 1958

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A. INTRODUCTION

The Geological Survey Department of the Bechuanaland Pro­tectorate has its headquarters at Lobatsi in the south-eastern por­tion of the Territory and these are provided with a mineralogical and chemical laboratory, drawing office facilities, a library and a museum.

The Geological Survey was established on the 1st April, 1948 and in the eight year period to 31st March, 1956 was financed wholly by grants made under the Colonial Development and Welfare Act. A new 4-year Geological Survey Scheme was approved in April, 1956 and it was decided that during the life of this scheme the Bechuanaland Protectorate Government would pay a proportion of the recurrent expenditure. During the period 1st April, 1956 to 31st March, 1957 the local contribution by the Protectorate Government was 25 per cent. of the recurrent expenditure and in the financial year 1957/58 this contribution was increased to 50 per cent. of the recurrent expenses. This contribution will continue at the rate of 50 per cent. of recurrent expenditure in the final 2-year period. The value of the Geological Survey towards general development prospects in the Territory is thus being acknowledged by this gradual takeover of a proportion of the recurrent expenses by the Territory's ordinary estimates. In this manner the Geological Survey is graduating from a totally grant-aided scheme to a Territorial responsibility. The present arrangements will continue until March, 1960 and present indica­tions are that after that period the Geological Survey will become an even more integral part of the Bechuanaland Protectorate Govern­ment services.

Geological Survey work in the Territory is directed along three main lines. These are (a) the geological mapping of all the exposed areas in the Territory, (b) mineral survey including field and lab­oratory examination of mineral depOSits and the survey of the poten­tial coal resources of the Protectorate and (c) the development of underground water supplies in the Territory. The Department employs geophysical prospecting techniques in mineral exploration and hydro geological work and owns three core drilling machines which are engaged on mineral survey. Close liaison is maintained with other Government Departments, particularly with the Boring Branch of the Public Works Department.

Since its inception in 1948 the Geological Survey has always experienced considerable difficulty in recruiting and in retaining senior professional staff. The range of the Geological Survey's activities has increased immeasurably over the past few years and this shortage of geologists has neoessarily meant that progress in certain phases of Geological Survey work has been slowed down. Unfortunately this has principally affected the progress and tempo of the regional reconnaissance geological mapping' programme which was commenced in 1955, It is particularly unfortunate, in view of the importance of the production of basic geological maps of the Territory in regard to general development prospects, that the map­ping programme in particular has had to suffer from this shortage

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of staff. However, in a semi-arid territory such as the Bechuanalalld Protectorate a Geological Survey has an important role to play III water development work and in order to fulfil its function in Lhlu regard it has been necessary to employ available professional sLIl.11' as far as possible equally on water development work and ()Il geological mapping. Without basic geological maps water devo]o!' ment work is naturally rendered more difficult and attention 111111 thus been paid in mapping programmes to areas where undergroulld water development scl18mes have to be implemented. This 11ll/l necessarily restricted the amount of work possible on direct min",., .. 1 survey.

The Geological Survey continued to experience a shortag'c ()f scientific staff throughout the year under review but it is gratify i Ill{

to record that towards the end of the year the prospects of recr'ui Li Ill<

additional geologists improved and it is hoped that early in the IWW

year the Senior Service staff will be almost up to full strength. During 1958 four geologists were available for field du I.i ""

throughout the year and a balance was maintained betwoolI geological mapping and work in connection with water boreholo siting for the 5-year Underground Water Development SChOlllO which is being implemented in the eastern Protectorate. In additi()lI, coal exploration work has continued and one geologist combillod this work with regional reconnaissance mapping. Quarter-dog.",", square geological mapping was undertaken in the Bamangwato alld the Bakwena Reserves. Short reconnaissance surveys were alH(J undertaken in the north-western Protectorate in the Batawal'" Reserve and the adjoining Crown Lands, and in the western Balll(' waketse Reserve and the southern Crown lands. During the yea!' " total of 3,000 square miles was mapped by two geologists and Lw() quarter-degree sheets were completed. A total of eleven quarter-deg."IIII square sheets covering some 12,000 square miles has now been map]",,1 to a scale of 1 : 125,000 since the start of the systematic regiollll.! reconnaisance mapping programme in 1955. While a consideralllu portion of the Bechuanaland Protectorate is covered by younglll' aeolian sands this area mapped to date only represents a smll.!! portion of the total mappable area of the Territory. It is hoped (.JlltL the new recrui ts now coming forward will enable the DepartmenL [.0

increase the tempo of the present mapping progrn.mme. The inte!'''/l!, already aroused by the publication and examination of the geolog·iclI.1 information resulting from those areas which have been mappecl [.() date is a good indication of the importance which mining and P]'OI\ )lecting organizations place on Geological Survey quarter-cleg"'(J(J square geological map sheets.

Mineral survey work has been confined to continued investigll. tion of the potential coalfield areas at Morapule, west of PalaJl'y(J, and in the vicinity of Mamabule, both these areas lying in LiI(J Bamangwato Reserve. A major contract drilling programme WIIII

completed in the detailecl investigation of the Morn.pule coalfi<>ld n.rea in Febl'uary and throughout the year Departmental core drill i Ill< has been carried out in the Malnabulo area. Assistance has also l)()(lll

rendered by the Departn1ent to a nutnganese 111i110 which opened II1

the Protectorate during the last quartor of 1957 and core drilling WIl.I1

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carried out in an attempt to prove extensions to the known mineral­ization. In the Bangwaketse Reserve the Marlime Ohrysotile 001'­

poration, who were awarded a Orown Grant to prospect for and mine manganese over a limited area south of Kanye in 1957, were awarded an extension to their Orown Grant for manganese rights to cover the whole of the Bangwaketse Tribal Territory. This Oompany was engaged on active prospecting work during the last quarter of the year in all areas underlain by promising geological formations.

At the beginning of the year the Department had been in­vestigating two asbestos occurrences but this work was discontinued in view of the disappointing results which were obtained in both areas.

Interest continues to be displayed in the mineral resources of the Protectorate and a number of applications were receivod, both from individuals and from mining organizations, for prospecting rights over various areas in the Territory. However, with tho ex­ception of the extension of the Marlime Ohrysotile Oorporation's Orown Grant for manganese to cover the whole of the Bangwaketse Reserve no other Orown Grants were issued during the poriod undor review. Negotiations still continue on an application by a mining group for a mineral concession over the whole of tho Bamangwato Reserve.

The Geological Survey continued to be responsiblo for the selection of the individual borehole sites and field control of tho contract drilling being carried out in the eastern Proteotorate under the five year, 1955-60, Underground Water Development Soheme which is financed by Oolonial Development and Welfare l"ullll D.2039. Field control of this programme ·is exercised in collaboration with the Drill Superintendent of the Water Boring Branch of the Publio Works Department and close liaison was also maintaino<l with this officer in connection with the Departmental drilling preg-.'ammo. During the greater part of the year the Geological Survoy undortook site selection for all drilling rigs of the Water Boring- Branch. Tho Geological Survey is far more directly concerned with the dovelop­ment of the underground water resources of tho Protootorato than the Pnblic Works Department and consideration has bOon given in the past to the transfer of control of the Boring Branoh from the Public Works Department to the Geolog'ical Survoy. l"ollowing further discussions on this subjeot it has now been docJdocl that from the 1st April, 1959 the Boring Branoh will fall undor tho clil'ooL control of the Direotor of Geolog'ical Survey and the Geological Survoy will be responsible for the development of the undorground waLor resources in the Protectorate to the stage where productive bore­holes are ready to be equipped. The actual equipping anti Lilo main­tenanoe of pump equipment will continue to be tho prorog'ative of the Public Works Department. It is hoped, when this now arrange­ment is in operation, that there will be greater effiCiency, noL only in the actual drilling carried out by the Boring Branch !Jut also In the success ratio !Jeing achieved by the Geolog'ical Survey in iLs Siting programme.

Under the water development scheme in the oastorn Pro­Lectorate the programme for the Bangwaketsc Heservo was oom-

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pleted in June and by the end of the year the programme for 1,,,, Bakgatla Reserve was also nearing cOlnpletion. Contract dri I J j III~ has also been in progress in the southern Bamangwato Reserve :1.1111 the greater portion of the scheme for that area has now been i '" plemented.Towards the end of the year, when it became appal'<·,,1 that the full Bamangwato underground water development sc]"""" could not ])e implemented with the remaining footage avaibl>l" under the contract drilling programme, it was decided by the Tri hili DeveloPlnent Comlnittee to nalne certain priorities for village :1,1111 agricultural supplies and drilling in this Reserve was sllspell!il·d while the Geological Survey undertook the necessary site selecl.illl! in the areas indicated.

Contract drilling under the direction of the Geological Sell·V".1' has also been in progress in Ngan1iland and in the northern 1'1"0 tectorate where the Geological Survey opened a new cattle roll 1.11 from Dugwe Quarantine camp to Shashi siding to enable cattle r,·"", the north-western Protectorate to be brought more easily to Ihll line of rail. During the year 136 boreholes were drilled on Hi I"" selected by officers of the Geological Survey. One of these w"" abandoned due to drilling difficulties and of the 135 completed b"I'II holes 95 boreholes were successful, with a success ratio of 70 per '""11 ..

The Geological Survey Department was represented at 1,,,, first Annual Congress of the Geological SOCiety of South Af,·i,·I\., held in Johannesburg in February, by the Director accompanied IIV Mr. O. J. van Straten and Mr. C. M. H. Jennings. Owing to the ill health of the Director the Geological Survey was unfortunately ""I. represented at the meeting's of the Association of African GeoloRi "" I Surveys hcld at the conference of the C.C.T.A. Regional Commitl""" in Leopoldville in July.

A welcome visit was paid to the Geological Survey in Aug,,"1. by Dr. F. Dixey, Director of Overseas Geological Surveys, who sp",,1. several days in the Protectorate and gave valuable advicc '''' geological and administrative problems resulting from the expl'" si on of the Department. Discussions were also held with Dr. Di '''.v and the Resident CommiSSioner, Mr. M. O. Wray, on the question of the future of the Geological Survey Department particularly a.ri.II" the close of the present Colonial Development and Welfare Sch""", in 1960.

The High Commissioner, Sir Percivale Leisching and Lad.v Leisching, accompanied by the Resident CommiSSioner, paid a Villll. to the Geological Survey in January on the occasion of the 11 igll Commissioner'S farewell tour of the Bechuanaland Protecto}'(l,Ln, The Deputy High Commissioner, Mr. T. V. Scrivenor, also paid " visit to the Geological Survey during the course of the y"",.. Prominent visitors from the United Kingdom included Mr. C. J. M. Alport, Parliamentary under-Secretary of State for Commonwoall.l, Relations and Mr. G. E. B. Shannon, Assistant under-Secretary of State, Commonwealth Relations Office.

During 1958 the Geological Survey headquarters at Lo))"l.ld were also visited by representatives of a number of ll1ining hOll~i(\li who wished to exan1ine geological maps and plans of the vari()ttll areas in whieh thcy were interested and also to discuss the possibi I i I..v

of obtaining prospecting rights over certain areas in the Protec­torate.

B. STAFF

Mr. D. Green, Geologist, returned from overseas leave in February. Mr. E. P. Wright, Geologist, resigned on the expiration of his contract term in June.

Mr. M. T. Jones was appointed to one of the vacant posts of Geologist and assumed duty in the Protectorate at the end of November. Mr. I. Gerrard was appointed to another vacant post of Geologist and assumed duty at the end of December. An application has been received in respect of the third vacant post.

Mr. L. A. Bure, Scientific Assistant to the Chemist-Petrologist. resigned at the end of September. No steps have been taken to fill this vacant post of Laboratory Scientific Assistant as an application has been made to upgrade the post to that of Chemist. With the ex­pansion of the Geological Survey and the increase in the Survey's range of activities it is no longer possible for the incumbent of the post of Chemist-Petrologist to pay full attention to chemical work in the laboratory. It is considered that there is sufficient chemical work to warrant the appointment of a qualified Chemist and it is thought that when approval for upgrading the post has been obtained, and the post has been filled, that there will be a great increase in efficiency in the scientific work of the Department.

Mrs. L. D. Mallen, Lady Clerk in charge of the Library and Survey records, resigned in January. Mrs. M. Kerr was appointed to this post in February.

A new post of Higher Grade African Clerk was introduced into the establishment to replace one post of Lady Clerk and Mr. S. Mahloane was appointed to this post in December.

The strength of the Department on the 31st December, 1958. with figures for the establishment shown in brackets, was as follows:

Senior Service Staff 15 (17) Junior Service Staff 53 (69)

The classified establishment of the Geological Survey and the Senior Service Staff with the period of duties servod by indlv!(!ual officers is shown in Appendix r.

C. FINANCIAL SUMMARY

The 4-year Geological Survey scheme for 1956-60, which was approved in principle by the Secretary of State in 1956, received a grant from the Colonial Development and Welfare l"und D.2891 to cover expenditure for the first two-year pcriod to tho :llst March. 1958. Supplementary provision was then provided to continue 0"0-logical Survey work in the Territory for the final 2-yOlU' pori od unt.il 31st March, 1960. During the first year of the IUc of C.D. and W. Scheme D.2894 the local contribution towards recurront oxpenses made by the Bechuanaland Protectorate Government was 25 p"r ccnt. of the recurrent expenditure. This was increased to 50 PCI' cont. of the recurrent expenditure in the financial year 1957/58 and will con­tinue at this rate during the final2-year period of tho presont scheme.

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the north-east of the main line of the porphyry which extends in a north-easterly trending, cigar-shaped mass from the Mabele a Pudi hills to the Shulabompe hills, Further exposures of Ghanzi Beds have been located to the south-west of the Mabele a Pudi-Shulabompe hills line and the extension of these rocks benea,1;h sand cover has been proved by recent boreholes drilled in this area, No evidence has yet been obtained which allows a definite statement to be made concerning the age relationships of the Kgwebe Porphyry and the Ghanzi Beds. The Kgwebe Porphyry is possibly the younger and intrusive into at least part of the Ghanzi Beds but there is also a possibility that it is an older formation which has been infolded in the Ghanzi Beds orogenic period. The actual contact between the Ghanzi Beds and the Kgwebe Porphyry has not been observed but, rather than being a faulted one, it would appear more probable that infolding has taken place and that both formations have sub­sequently been affected by the prominent WNW-ESE trending faults which have displaced the fault blocks of the Kgwebe and Makgabana hills. This infolding could have occurred irrespective of the relative ages of the two formations.

In the area south-west of the Shulabompe hills, where further exposures of the Ghanzi Beds were located, there are relatively ex­tensive outcrop areas of an epidotised, amygdaloidal basic lava. This is undoubtedly the equivalent of the Toteng diabase which has been described by Passarge and it can now be stated fairly definitely that the Toteng diabase is an original, interbedded lava fiow.

F. WATER SUPPLY

During 1958 the development of underground water supplies continued to form an important phase of the Geological Survey's activities and throughout the year two geologists were engaged speCifically on this work. The Department continued to be re­sponsible for site selection for the 5-year, 1955-60,Underground Water Development Scheme which is financed by the Oolonial Development and Welfare Fund Scheme D.2639. Under this scheme a major con­tract drilling programme is in progress in the eastern Protectorate and a total of some 65,000 feet of drilling will be carried out. By the end of 1958, 55,347 feet had been completed. Throughout the year the Geological Survey was also responsible for borehole siting for the Departmental drilling programme and as has been mentioned earlier in this report the Geological Survey will assume full control over the activities of the Water Boring Branch from the 1st April, 1959. The Department has also been implementing a development programme in the Batawana Reserve which is being carried out partly by contract and partly by Departmental drilling. Surveys in connection with water development work have been undertaken in various parts of the Territory and during the last quarter of the year the Geological Survey opened a new cattle route from Dugwe to Shashi siding to enable cattle from the north-western Protec­torate to be brought more easily to the line of rail. Assistance has also been given to townships and villages and to the cattle export route drilling in the central Kalahari. In connection with township supplies the Department has been undertaking geophysical surveys

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and supervising test drilling in an attempt to augment the suppiioll for Lobatsi which are at present being pumped to the limit of thel,· capacity.

The water development programme in Bangwaketse Reserve wall completed in June. A total of 16,107 feet was drilled by contract in (n boreholes on sites selected by Mr. P. T. Wilson and of these forty-two were successful. Thirty-nine boreholes had been completed by Call,

tract in 1957 and of the 24 boreholes drilled during 1958 seventoell were successful representing a success ratiO of 70.8%. A statistic,,1 summary of the drilling carried out in the implementation of tllO water development scheme in the Bangwaketse Reserve is as followH:

The total number of boreholes drilled 63 Number of successful boreholes 42 Percentage success .. 66.6% Total footag'e drilled 16,085 feet Footage of successful boreholes 10,652 feet Average depth of boreholes 255 feet Average depth of successful boreholes 253 feet Total tested potential yield of boreholes 28,560 g.p.h. Average yield of successful boreholes 680 g.p.h. Contract drilling was started in the southern Bamangwato aro"

in February, following geophysical surveys carried out by M,·. C. M. H. Jennings in 1957 and by the end of September 34 boreholeH had been completed of which 28 were successful representing a succeHH ratio of 82%. The majority of these sites were selected for a ncw grazing area in a Kalahari region underlain by sediments and lava" of the Karroo System, Sites were also selected for village and agri­cultural purposes in areas underlain by pre-Karroo rocks. It becamo apparent in the second half of 1958 that it would not prove possiblo to implement the full Bamangwato underground water developmcl1 L scheme with the available footage remaining under the contraot. drilling programme. A meeting was therefore held with the Tribal Authorities at which a decision was taken by them to list certain priorities for agricultural and village supplies and contract drilling' in this Reserve was suspended in October while the Geological Survey undertook the necessary site selection in the new area" which had been indicated by the Tribal Authorities. By the end 01' ohe year a total of 25 sites had been selected by Mr. Jennings.

Contract drilling was also carried out in the Bakgatla Resel'vo commencing in June. Geophysical surveys and borehole site seloo­tion for the village and agricultural lands supplies required in this district were undertaken by Mr. Wilson. By the end of the year It total of 8,775 feet had been drilled in 35 completed bOl'eholes. Tho areas in which the boreholes were required are all extremely difficulL ones in which to locate adequate potable and permanent underground water supplies. Of the 35 boreholes drilled 20 were successful.

The Director undertook a survey of the south-western Crown Lands with the Drill Superintendent in March. Areas in which watol' development schemes are to be implemented in the Molopo RivOl' area were inspected and the survey was carried as far west as tho Kalahari Gemsbok Park in order to investigate certain sites whicll were tentatively proposed for that area. A number of sites were

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selected in the southern Crown Lands during the course of this survey by the Director and a report was submitted to Government on the future development prospects for this general region.

In April and May the Director and Mr. Jennings visited Ngami­land to carry out geophysical surveys and water borehole site selec­tion in the marginal Hainaveld area as part of a water development programme which is being implemented there under the direction of the Geological Survey. No boreholes had been drilled previously in this rather inaccessible area and the survey was essentially a preliminary one with the object of selecting a number of test sites, the results of which will determine the future Course of any develop­ment programme in this area. Results to date have been disappoint­ing and in two cases boreholes have struck saline, fissure supplies which had not been indicated by the geophysical depth probe curves. It is apparent in this area, even though exposures are present over relatively large areas and the sand cover is frequently thin, that present day conditions of recharge are limited and difficulty will therefore be experienced in locating potable supplies.

Test drilling was also carried out in Ngamlland in the area south-west and west of Lake Ngami on sites selected by the Geo­logical Survey during 1957. This area had been suggested as a suit­able area for intensive development but following a survey there in 1957 the Director recommended that a number of test sites should be drilled as it did not appear likely that potable suppliss would be obtained in many parts of this area. Four test boreholes were drilled and as was expected, these boreholes were either blank or yielded saline water supplies.

The Geological Survey continued to undertake borehole site selection for the cattle export route in the central Kalahari region. During the first half of the year attempts were made to develop potable ground water horizons which are present at depth in the middle Ecca sands tones and grits below upper, confined saline ground waters in the higher members of the Ecca Series. Attempts had been made to develop a supply at Boritse pan during 1957 but in the borehole drllled in the pan itself it did not prove possible to seal off the saline ground­water to allow the underlying potable ground water horizon to be tested properly. A second borehole was then drllled and sited one mile to the north of the pan to avoid the possibility that the deep acquifer might be contaminated in the pan area itself. While drilling was in progress at this second site the horizons encountered were correlated with those of the first borehole, changes in rest level were noted and frequent analyses were made on samples of the ground­water taken with increasing depth. By these methods it proved pos­sible to stop the drilling in this second borehole at a point 20 feet above the known acquifer to allow a seal to be made. Considerable difficulty was experienced in making this seal but when an effective seal had apparently been made the borehole was continued and at the predicted depth range of 970 to 980 feet a supply was encountered. The static water rest level from surface decreased by 135 feet to a new level of 345 feet from surface and chemical analysis showed that the total dissolved solids content of the water in the borehole column had decreased from 18,968 p.p.m. to 7,188 p.p.m. Subsequent pump

26

tests and chemical analyses, however, proved that an effective sca.1 had not becn made and that there was a leak from the upper salillO horizons. The technical difficulties involved in effecting a perfcet. seal have not yet been solved and drilling was therefore suspcnded at Boritse pan. This work carried out by the Geological Survey and the Boring Branch of the Public Works Department has shown thltt. it should be possible to locate deep potable supplies in other area.H underlain by similltr geological formations in the central Kalahari where near-surface and often deeper supplies are highly saline. Tho development of deep potable supplies of this nature will necessaril.v be a matter of some difficulty and expense, but the Geological Surve.v has now accumulated sufficient data on the hydrogeology of tlHl central Kalahari to show that unless these supplies can be developed, water supply in much of this reg'ion will be dependent on weak, near­surface and seasonal supplies in the vicinity of pans and extensivo tracts of country will remain waterless. In this connection tllo sources of recharge of these acquifers in the central Kalahari is 01' particular importance and the distance from these sources will be­come a limiting factor to potability. For this reason it is important. to define these limits in the central Kalahari region.

On the available geological and hydrological data which haH now been accumulated by the Geological Survey it is possible to develop the Ghanzi cattle export route from Kang to the south-east, the difficult area remaining from Kang north-west towards Lono Tree pan borehole. It was accordingly decided to develop boreho]eH at suitably spaced intervals in the south-eastern section and on the completion of the experimental work at Boritse pan the Geological Survey sited a borehole in the central region between Kang and Kn­kong and a further potable supply was located there. Drilling is now being carried out to the east in an attempt to locate potable supplicH to provide watering pOints for the local population, following whieh further work will be undertaken for the cattle export route itself.

A second cattle route in the northern Protectorate was opencd by the Geological Survey during the last quarter of the year. ThiH cattle route is from Dugwe quarantine camp to Shashi Siding and iH designed to facilitate the movement of cattle from the north-western Protectorate to the line of rail and thus to the abattoir in the south­east. Geophysical surveys were undertaken by Mr. Jennings in September and contract drilling was commenced during the second half of that month. Six sites were selected by Mr. Jennings and all these boreholes were successful, although in one case the supply developed is weak and an alternative site will have to be selected.

There has been a considerable expansion of the Lobatsi Town­ship over the past few years and the present water requirements of the three main consumers, the Colonial Development Corporation, the Rhodesia'Railways and Government, are now estimated at some 85,000,000 gallons per year, which is an increase of nearly 25,000,000 gallons over the estimated requirements in 1955. Future require­ments for Lobatsi are estimated at some 143,000,000 gallons per year. With the exception of a relatively small supply obtained by the Rhodesia Railways from their dam, which normally only holdH water for a limited period following the rainy season, this very larg'c

2'7

amount of water is supplied from boreholes and three groundwater basins are being tapped. These groundwater basins are already being pumped to the limit of their capacity and the expansion of Lobatsi and the consequent increase in water consumption has thus been a matter of considerable concern. There is no site in the immediate neighbourhood, within ecenomic pumping distance of Lobatsi, for a surface water conservation scheme and Lobatsi will have to depend for its future increases in supply on underground water supplies. In an attempt to develop new ground water basins test drilling was car­ried out on the B.S.A. Company Estate which lies 2 to 3 miles north­east of the township, following geophysical surveys carried out there by Mr. Jennings. The results of this programme have fulfilled the expectations held out for this area and several high yielding bore­holes have been developed. One borehole gave a yield of 7,000 g.p.h. over a 72 hour test period with a drawdown of 80 feet. At the end of this period the pumping rate was increased for a short period to over 9,000 g.p.h. Geophysical surveys are being continued in an attempt to develop further groundwater areas.

A tabulated list of boreholes drilled on sites selected by officers of the Geological Survey is shown in Appendix Ill. A total of 136 bore­holes were drilled on sites selected by the Geological Survey during 1958. Of these one was abandoned and of the 135 completed boreholes 95 were successful representing an overall success ratio of 70,/\,. This includes 6 test boreholes and if these are excluded the succoss ratio is 73%.

G. ENGINEERING GEOLOGY

The core drilling programme carried out by the Publlo Works Department to test the foundation rock of the proposod Mahalapye dam site was supervised by Mr. van Straten. A geological survey of this proposed dam site had been carried out by Mr. Cullen in 1957. Ten boreholes totalling 164 feet were drilled under Mr. van Straten's direotion and pressure tests carried out to determino tho rate of leakage in oertain of the boreholes. The results of thoso indicate that grouting of the foundation rock will be necessary bororo a dam is built on this site.

H. HEADQUARTERS WORK (a) Laboratory

The Laboratory has continued to provide chemic!.l and petro­logical services for officers of the Department and work is under­taken for other Government Departments and the public. The lab­oratory section is also responsible for the preparation of thin sec­tions of rocks for petrological study and also supervisos tho flling of sludge samples from all the drilling rigs operating in tho 'l'erritory. During 1958 the laboratory space was expanded by the establishment and equipping of a separate optical laboratory. Additional oquip­ment purchased during the year included a spectrophotometer and a camera lucida attachment for petrological microscopes.

In addition to petrological work on rock samples and borehole sludges, the Laboratory was mainly concerned with chemical analyses of ground-waters and surface waters from the Protectorate.

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The great majority of these analyses were performed by Mr. Buro. Suites of samples from Boritse pan were analysed in connection with a hydrogeological investigation undertaken at this locality and the combined results of the work indicate that potable water exists at. depth below extremely mineralized ground waters. A suite of samples from the wells and boreholes at Gaberones was analysed as a neces­sary prelude to the construction of a new reticulation system. This work was performed on behalf of the Public Works Department who required the results for an assessment of possible corrosion to tllO pipeiines. In addition suites of water samples from the Molopo River. western Ngamiland region and the Woodlands water development. area were analysed in connection with potability studies.

Determinations were performed upon manganese ores from tho Ramoutsa and Ootsi occurrences for the mining company operating' in this district. At the request of the Agricultural Department. solubility de terminations were done on Boric acid-Borax mixture," intended for use as a wood preservative.

A statistical summary of laboratory work for the year und",' review is as follows:­

Borehole sludg'es filed Chemical Analyses: Waters: 117 samples Ores etc.: 18 samples

(b) Library

5,390 from 231 boreholes.

1,053 de terminations. 21 determinations.

A small library is maintained at Lobatsi for the use of tho SCientific staff. Selected reference books are purchased and a num))ol' of scientific periodicals are taken covering the range of subject,s studied by the staff.

Mrs. M. Kerr was aPPOinted Lady Clerk in charge of the librar.Y and Survey records in February, 1958 in place of Mrs. L. D. Malloll who resigned at the beginning of the year.

(c) Drawing Office Further re-organization of the Drawing office section was carriod

out and additional equipment was purchased. A number of pro liminary plot quarter-degree square map sheets of the north-easto!'1I portion of the Territory were received from the Overseas Survo.Y" and these are proving invaluable for the regional geological mappilll{ programme. Some 40 maps, plans and diagrams illustrating LIlO results of geologist's field work were prepared. A new provisioll,,1 geological map of the Territory to the scale of 1 : 1,000,000 was drawlI and issued with the Annual Report for 1957 at the reduced scale er 1 : 2,000,000. A plan of boreholes sections and a borehole locality nmp were prepared to accompany a Mineral Recourses Report. Assistanotl was also rendered to other Government Departments.

The following is a list of maps and plans prepared in the drawillK office during the year:

Reconnaissance Geological Map of Western Ngamiland 1: 250,000 Provisional Geological Map of the Bechuanaland

Protectorate Manganese Ore Deposits at Ramoutsa

1 : 1,000,01111 1 : 2,500

2()

Naka La Phala Iron-Ore Deposit .. Comparative Stratigraphical Columns

1 : 12,000

Borehole Sections, Morapule Coalfield, Palapye Coal Prospecting, Palapye Area ..

Area.

Coal Prospecting, Palapye Area .. Coal Prospecting, Palapye Area .. Contract Drilling Sites, Palapye Area. Bechuanaland Protectorate Potential Coal Areas. Iso-gamma Contour Plan of the Magogaphate Area Geological map of the Kihabe Valley Geological map of the Goha Hills Water Development Plan of the Bangwaketse

Reserve Water Development Plan of the Bakgatla Reserve Water Development Plan of the Serowe Area Water Development Plan of the Palapye, Madinare

1 : 63,360 1 : 21,120 1 : 30,000

1 : 6,000 1 : 8,500 1 : 8,500

1 : 125,000 1 : 125,000 1 : 250,000

and Bobirwa area.. 1 : 250,000 Water Borehole Sites at Totome .. . . 1 : 12,250 Water Borehole Sites at Maitengwe .. 1 : 12,250 Water Boreholes in the Central Kalahari 1 : 1.000,000 Water Borehole Sites in the Western Hainaveld 1 : 250,000 Water Development Plan of Southern Ngamiland 1: 250,000 Water Borehole Sites for the Cattle Route from Dugwe

to Shashi Siding .. 1 : 250,000 Water Development Plan of the Southern Bamangwato

Reserve 1 : 250,000 Map showing existing water boreholes at Lobatsi 1: 100 Bori tse Pan Borehole Sections. Water Development Map of the Bakwena Reserve Map of Mahalapye dam-site Plan of Mahalapye dam-site showing section along

1 : 250,000 1 : 800

centre line 1 : 600 Plan of Mahalapye dam-site showing section of major

joint trends 1 : 600 Plan of Mahalapye dam-site showing Joint Systom in

the Granite Bedrock .. 1 : 480 Revised Outline of the Makarikari pan. Map of the Botletle River. Map showing form-lines of Lobatsi area .. Map showing Farm Boundaries in the Ghanzi

Block .. Sketch Map of the Bamalete Reserve Sketch Map of the Bakgatla Reserve Map of the Barolong Farms " Diagramatic Sketch of Drodsky's Caves Plan of Drodsky's Caves.

1 : 125,000

1 : 250,000 1 : 63,360 1 : 20,000 1 : 125,000

In addition l6 tracings of various geological maps and other plans were prepared and 15 existing maps and plans which had been damaged were re-draughted. Assistance was also rondered to other Government Departments as follows:

80

(a) Education Department: Map showing Educational Facilities in the Bechuanaland Protectorate 1: 1,OOO,O()O (Prepared to accompany the Triennial Report (of the EducationDepartment).

(b) Department of Posts and Telegraphs: Topographical Map of the Eastern Protectorate 1: 500,000 7 Plans of Telephone crossings over the Existing Railway line.

(c) Medical Department: Map showing the Malarial Areas in the Bechuanaland ProtectOl ate 1: 4,OOO,O()O Map showing the Bilharzia Areas in the Bechuanaland Protectorate 1: 4,OOO.()()()

(d) Reports and Publications The Annual Report for 1957 was published but owing to delay" j 11

sending the text to the printers it will only be possible to distrilJl,LII the report early in 1959. The Records of the first fifty borehol"" drilled by the Department in coal exploration was bound and iI j:<

tributed during the year. The Records of the Geological Survey [",. 1956 were in the hands of the printers by the end of the year and i I, III expected that these will be available for distribution early in 1!l!>!1. The publication of the detailed examination of the coalfield area 11.1,

Morapule is in the course of preparation and sections of borellOllI profiles and maps to accompany this publication have been prep",."" in the drawing office.

The undermentioned reports were prepared. By C. BOOCOCK:

Progress Report for the Half-Year ending 31st December, 1%'(, Report on the Water Borehole Sites to be drilled by the Beelll' . analand Protectorate Government in the Kalahari Gems!>o I, Reserve. Report on the Water Development Programme in the Soutl""·,, Crown Lands. A Review of the Underground Water Development Scheme 1'",' the Period April 1, 1956 to March 31, 1958. The Geological Environment of Copper Deposits in the Bc"'III' analand Protectorate. Supplementary Notes for the Resident Commissioner's Add,.",,,, to the African Advisory Council. Notes for the Annexure to His Honour's Address to the :1111,1, Session of the African Advisory Council. Progress report for the Half-Year ending 30th June, 1958. Report for the Advisory Committee on Overseas Geolog'y Il.lld

Mineral Resources, 1958. Mining in Bechuanaland. Annexure to His Honour, The Resident COlnmissioner's Add!'(~IU1 to the 61st Session of the European Advisory Council. A Note on the Development of Potable Supplies at Depth in 1,111, Central Kalahari. (Prepared in collaboration with Mr. O. J.IlIIII Straten).

Official Number Locality

887 Marathadibe, Bangwa­ketse Reserve

883 Ranaka, Bangwaketse Reserve ..... .

885 Ditelele (Lorijana), Bang­waketse Reservp. ..

884 Sita Pan (Mamose), Bang­waketse Reserve

888 Ngalabaloi, Bangwaketse Reserve ..... .

886 Gasita, Bangwaketse Re­serve

892 Matsutsu, Bangwaketse Reserve

889 Dinoge, Bangwaketse Re­serve

890 Samane, Reserve

Bangwaketse

891 Mogobewadinonyane, Bangwaketse Reserve

SOl Loba:si To~r-.;p

;e: _,,:-.:.G..::"::' ~ -;;::-~,;;:

APPENDIX ill

Boreholes drilled on sites selected by officers of the Geological Survey

Depth in feet

350

183

200

355

Yield G.P.H.

240

80

100

600

Depth water

struck in feet

285

145

129

286 & 324

Static water rest level from

surface in feet

262

108

110

280

Geology

Recent deposits (280') and Basement Com­plex.

Gaberones-type granite.

Recent deposits (60') and younger micro­granite.

Recent deposits (150') and younger granite. c.

500

220

450

2:73

180

264

2SJ

.:B:

Blank

300 45 & 200

Blank 369 (45 g.p.h.)

1,350 218

300 160

900 215

s..~ 63 &: 13:1

:...x

21

298

187

125

194

.3.3

:...::t:

Recent deposits (290') and granite.

Recent deposits (30') and quartzite (Trans­vaal System) with basic intrusion

below 120'.

Recent deposits (300') and granite.

Recent deposits (20') and shale and quart­zite (Pretoria Series, Transvaal System).

Basic lava (Pretoria Series. Transvaal System.)

Recent deposits (150') and younger granite.

=:>G:O....,,~.~ ('I"- ~-;-3.al Syste!::.'.

:::: •. ::...."--: ~.-.: ::'::'-:::::-" "";.7

"

Official Number Locality

905 Ramatlhabama Police Camp

906 Sekutani, Bangwaketse Reserve .... _. _,

907 Sekutani, Bangwaketse Reserve ..

908 Jwana, Bangwaketse Re-serve .. .. .. ..

909 Mokhuma, Bangwaketse Reserve ....... .

910 Sekutani, Bangwaketse Reserve

911 Lehobo, Bangwaketse Re-serve .. .. .. ..

913 Ramatlhabama Police Camp ........

915 Ramatlhabama Police Camp

917 Lobatsi Township .. 918 Mrnanakalengwe

(Shoshong), Bamangwato Reserve

919 Lobatsi Township 920A j\fabuli, Eangwaketse

Reserve .. _. .. 921 Dikudu, Bangwaketse Re­

sence 923 Woodlands, LobatsiBlock

924 Tlanege, Ba~o-waketse Reserve ....

925 Shoshong, Bamangwato Reserve

Depth in feet

217

515

500

345

346

400

240

193

Yield G.P.H.

3,000

220

750

900

1,000

Blank

675

670

Depth water

struck in feet

117

460 & 485

320 & 390

315 & 320

290 & 310

132

125

StatiC water rest level from

surface in feet

108

379

200

302

271

130

104

90 Hole abandoned difficulties.

due to drilling

349 600 132 112

203 Blank

230

250 200

500

192

200

100 130 & 135 110

60 100 130 Blank

(30 g.p.h.) 3,900 45 35

1,350

tieo 90 81

ISO. 188 and 117 148

Geology

Basement Complex granitic gneiss and schist.

Recent deposits.

Recent deposits (330') and grey fissile shale.

Transvaal System quartzite and shale.

Transvaal System quartzite and shale.

Recent deposits (250') and felsite (Lobatsi Volcanic Series).

Waterberg System sandstone.

Granite (Basement Complex) and dolerite.

Granite (Basement Complex).

Transvaal System dolomite.

Basement Complex granite decomposed to 89 feet.

Dolomdte (Transvaal System).

Calcrete (110') and Alluvium. Chert Breccia (60') and dolerite.

Pretoria Series quartzite and shale (Transvaal System).

Gaberones-type granite.

Basement Complex granitic gneiss decom­posed to 138 feet.

co "',

Number Official

Locality

926 Kanye. Bangwaketse Re-serve .. .. .. .. ..

927 Pitsa, Bangwaketse Re-serve .. .. ..

928 Lelenamagadi pan. Southern Kgalagadi dis­

trict

929 Mokopong. Southern Kgalagadi-district ..

931 B.S.A. Western Reserve, Lobatsi Block .' .. ..

933 Lethekane, Bakgatla Re­serve

935 Selinya, Bamangwato Reserve

936 Kamawe, Bangwaketse Reserve

937 Shoshong (Morutwe Hill), Bamangwa to Reserve

938 Shoshong, Bamangwato Reserve

939 Mahudutshwe, Bang­waketse Reserve

940 Kalanka (Mosolotsane), Bamangwa to Reserve

942 Ledu (Lebung area). Bam­angwato Reserve

+ _'-~-"--"-. -=_.0 __ "'",-.,,-

"'-Y,;/i<ii;'ij,@}>/&W&.""i;iht:i!f:i;;;;;;/0fiijKJ;ii!;.;;"~i/fjj,i}:i ,.:,{"",-.

Depth in feet

445

261

807

210

150

70

150

120

300

350

182

268

400

3i£

Yield G.P.H.

Blank

Blank

Depth water

struck in feet

Saline 800 Supply

300 155 & 175

Blank

Blank 64 (30 g.p.h.)

1,540 60

750

Blank

1,000

90

860

250

':',..JW£

40

155

97

120, 131 & 138

270 & 345

::Jl: .. = ."-

. Static water rest level from

surface in feet

750

138

6

25

35

122

50

116

250

:.:.:::

Geology

Dolerite.

Granophyres (Lobatsi Volcanic Series).

Dwyka Series shale and sandstone (Karroo System).

Matsap Beds quartzite.

Dolerite.

Dolerite.

Calcrete (40') and Stormberg Series basalt.

Younger granite (Gaberones type).

Basement Complex granite, decomposed to 134 feet.

Decomposed Basement Complex granite.

Dolerite and serpentine.

Ecca Series sandstone and shale.

Cave Sandstone (Stormberg Series 200') and Ecca Series shales and sandstone (Ka.:.-I"'GC S::s:.e.::::',.

=-~-: ~ '~,- ~B$. ~-::::;:,?~

co 0>

Official Depth Yield Depth water

Nu.mber Locality in feet G.P.H. struck in surface Geology feet

945 West of Kabaganyane, Ngamiland .. 300 Saline 92, 115 85 Recent deposits (194') and Bodibeng sand-

Supply & 240 stone. Test borehole. 946 Shoshong, Bamangwato

230 Reserve 2,000 150, 170 148 Basement Complex granite, decompose & 190 to 190 feet.

947 Ledu area, Bamangwato Reserve 250 2,000 96 & 130 55 Cave Sandstone (Stormberg Series,

Karroo System). 948 Lebung area, Bamang-

wato Reserve 300 540 160 & 190 107 Calcrete (25') and Cave Sandstone (Storm-berg Series, KarrOD System.)

949 Le bung area, Bamang-wato Reserve 300 100 170 & 240 115 Cave Sandstone (Stormberg Series,

Karroo System). 950 Xudi Xaa, Ngamiland 400 Blank Recent calcareous sand. Test borehole. 951 Xau pan, Ngamiland 230 Blank Bodibeng sandstone (Stormberg Series. e;:,

KarroD System.) Test borehoZe. -l 952 Lobatsi Township .. 463 750 112 108 Alluvium and wad (160'), dolomite (Trans-

vaal System). 954 Lebung area, Bamang-

wa to Reserve 300 675 245 163 Calcrete (30'), basalt (245') and Cave sand-stone (Stormberg Series, Karroo

System). 955 Masoke area, Bamang-

wato Reserve 250 360 95 88 Cave Sandstone (Stormberg Series, Karroo System).

956 Lebung area, Bamang-wato Reserve 450 60 210 205 Cave Sandstone (Stormberg

Karroo System). Series,

957 Lebung area. Bamang-wato Reserve 3)) 540 160 & 250 130 Cave Sandstone (Stormberg Series,

Karroo System). 958 Molotoana, Bakgatla Re-

serve .' .' .. 250 320 116 & 180 115 Waterberg System shales and sandstone. 959 Lebung area, Bamang-

wato Reserve 310 750 246 & 295 134 Basalt (245') and Cave sandstone (Storm-berg Series, Karroo System).

Official Number Locality

960 Mamodungwa, Bangwa­ketse Reserve . . . . . .

961 Mabalane, Bakgatla Re-serve .' .. .. ..

962 Lebung area, Bamang­wato Reserve

963 Lebung area, Bamang-wa to Reserve

964 Khad u pan, N gamiland ..

965 Difudi, Bakgatla Reserve 966 Lobatsi Township ..

967 Lebung area, Bamang-wato Reserve

968 Lebung area, Bamang­wato Reserve

969 Lebung area, Bamang­wato Reserve

970 Le bung area, Bamang­wa to Reserve

971 Pala-Ia Morena, Bakgatla Reserve ..

972 Dipuduhudu, Bakgatla Reserve .. ..

973 Ramal'1,l'tetsi area, Bam­a:::J.gwato Resel'Ye

;":",!

Depth in feet

96

144

335

300

300

300 498

300

350

400

350

420

300

300

-Z:l

Yield G.P.R.

Blank

Blank

Depth water

struck in feet

300 305

1,500 160

Blank 130 (30 g.p.h.)

300 82 & 195 500 83

1,200 225 & 260

Blank

Blank

400 225 & 280

500 224

600 175 & 240

200 l10

...:; ''''7'';,~

Static water rest level from

surface in feet

285

137

175

80 63

186

188

202

170

83

Geology

Dolerite.

Acid lava and felsite (Basement Complex).

Recent <'eposits (90') and basalt (Storm-berg Series, Karroo System,).

Basalt (160') and Cave sandstone (Storm-berg Series, Karroo System).

Recent calcareous sands. Test borehole.

Shales and sandstone (Waterberg System?) Alluvium (30') shales (Pretoria Series,

Transvaal System). CO-'

Kalahari Beds (110'), basalt (195') and CD Cave Sandstone (Stormberg Series,

Karroo System).

Kalahari Beds (70') and Cave sandstone (Stormberg Series, Karroo System).

Cave Sandstone (Stormberg Series, Karroo System).

Calcrete (40'), basalt (100') and Cave sand­stone, (Stormberg Series, Karroo

System).

Waterberg System sandstone.

Waterberg System shales and sandstone.

Cave Sa-ndstone. Stormoerg Series (60') 2.::2.(: ECC-2~ Se:':~:3 ~b.2.~e 8.:2Cl :38.::':':3::o:::e

:_:~ ___ :::-:.-5-:-::= ;~"P3'::~~:::o::-,

Depth water rest Official Depth G.P.H. water level from Number Locality in feet Yield struck in surface Geology

feet in feet

975 Mogobe wa Matswere, Bakgatla Reserve .. 300 300 115 80 Basement Complex granitic gneiss with

basic intrusions. 976 Ramalwetsi, Bamang-

wato Reserve 340 50 110 & 310 90 before Cave Sandstone (Stormberg Series) with test dolerite intrusion.

198 after 977 Mathubudukwane, Bak-

gatla Reserve 120 900 55 & 60 40 Basement Complex granitic gneiss decom-posed to 80 feet.

978 Ramalwetsi area, Bam-angwato Reserve 200 500 95 73 Cave Sandstone (Stormberg Series,

Karroo System). 979 Masue pan, Bamangwato

650 Cave Sandstone (Stormberg Series, Reserve 250 70 & 120 51 Karroo System).

" 980 Mabalane, Bakgatla Re- o< serve 270 Blank Basic lavas (Derdepoort Complex ?).

981 Woodlands, LobatsiBlock 150 2,700 70 47 Shale and quartzite (Pretoria Series, Transvaal System).

983 Seleme,BakgatlaReserve 296 200 215 & 265 210 Waterberg System sandstone with dolerite intrusions.

984 Sequani, Bakgatla 120 750 Basic lava (Derdepoort Complex ?). Reserve .. 80 20

985 Lebung area, Bamang-wa to Reserve 370 750 850 250 Kalahari Beds (40'), basalt ~375') and Cave

sandstone (Stormberg eries, Karroo System).

936 Kwadibeleng, Bamang-wato Reserve 200 140 80 70 Syeno-diorite decomposed to 105 feet.

987 Ramalwetsi area, Bam-an.,.o-wato Reserve 450 1,000 375 250 Kalahari Beds (40'), basalt (375') and Cave

sandstone (Stormberg Series, Karroo System).

989 Malol wane, Bak"o-atla Reserve ...... 160 1,000 135 123 Amphibolite (Basement Complex).

990 Moralane, Bamangwato Reserve 206 200 125 87 Shushong Series (?) shales and sandstone

(125'). and syenite.

Official Number Locality

991 Segwati pan, Bakgatla Reserve

992 Shulabompe, Ngamiland 993 Mosetse, Bamangwato

Reserve 994 Boritse pan, Bakwena

Reserve

995 Lepara, Southern Kgala­gadi district

996 Papane (Mochudi), Bak­gatla Reserve ..

997 Shoshong, Bamangwato Reserve

998 Mogolegwa, Bakgatla Reserve

999 Marokolwane, Bakgatla Reserve

1000 Morwa, Bakgatla Reserve

1001 Mabalane, Bakgatla Re­serve .' .. .. .. ..

1002 Matlhage pan, Bakgatla Reserve .. ..

1003 Bodiakhudu, Bakgatla Reserve

1004 Mogolori (Palla Road), Bamang'lNato Reserve

1m3 X?:.:-X-'::7~':. ~:::-~?.::;--....... ;..:.: :-~~':-:'-::

Depth in feet

316

115

250

950

360

223

250

300

250

250

300

294

300

200

:~

Yield G.P.H.

Depth water

struck in feet

Static water rest level from

surface in feet

Blank 235 190 (15 g.p.h.)

Blank (Saline groundwater.)

320

780

Blank

100

Blank

83

235, 353, 388 394 & 940

190

Blank 217 (15 g.p.h.)

Blank

60 110 & 200

Blank

1,100 230 & 275

Blank

2,000 70 & 80

=O~ ;c.

83

406

100

170

70

130

60

Geology

Basement Complex granitic gneiss.

Ghanzi Beds quartzite.

Basement Complex granitic gneiss.

Kalahari Beds (155') and Ecca Series (Karroo System). Saline ground water -Test borehole.

Matsap Beds quartzite.

Basement Complex granitic gnel:5s.

Basement Complex granite decomposec1 to 190 feet.

Basement Complex granitic gnelst5.

Waterberg System sandstone.

Gaberones type granite.

Acid and basic lavas.

Basement Complex granitic gneiss.

Syenite.

Basalt (100') and Cave sandstone (Storm­berg Series, KaTToo System).

s-·-~:;_.:...=.-=- ;:'::"'='-:"':"::~;3 :='.~~=-:-=--: ~'._'-

"' o

Official Number Locality

1006 Matlhabanelo, Bamang­wa to Reserve

1007 Mochudi area, Bakgatla Reserve ..... .

1008 Woodlands, Lobatsi Block .,

1009 Bokaa, Bakgatla Reserve 1010 Woodlands, Lobatsi

Block .. .. .. .. 1011 Mokopong, Southern

Kgalagadi district .. 1012 Lepasha, Bamangwato

Reserve ..... . 1013 Lephalala Mogojane,

Bakgatla Reserve 1014 Ditshetshwaneng, Bak

gatla Reserve ..

1015 Ntshekeletse Bakgatla Reserve ....... .

1016 Mochudi, Bakgatla Re­serve

1017 Mamonye, Bakgatla Re-serve ...... .

1018 Mochudi, Bakgatla Re­serve

1019 Segoditsane, Bakgatla Reserve

1020 Magogodi, Bakgatla Re­serve .. .. .. .. .

1021 Moditola, Bamangwato Reserve

Depth in feet

160

200

500

250

500

197

300

250

350

260

300

300

200

300

250

235 :

Yield G.P.H.

Blank

135

500

120

7,000

550

235

250

360

Blank

120

180

1,200

90

1,300

200

Depth water

struck in feet

163

160

80

68

175

113

130

70

170 & 190

200

60 & 120

235

90

105

Static water rest level from

surface in feet

130

155

60

42

170

58

100

53

80

180

45

190

85

31

Geology

Ecca Series sandstone (Karroo System) overlying pre-Karroo dolerite from

60 feet.

Basement Complex granitic gneiss.

Pretoria Series Shales and quartzite (Transvaal System).

Basic lavas and dolerite.

Pretoria Series shale (Transvaal System).

Matsap Beds quartzite.

Granulite (Basement Complex).

Waterberg System sandstone and shale.

Granite and chlorite schist (Basement Complex).

Basement Complex granitic gneiss.

Waterberg System sandstone and conglo­merate.

Basement Complex granitic gneiss.

Basement Complex granite with basic intrusions.

Waterberg System sandstone with basic intrusions below 220 feet.

Waterberg System sandstone and shale.

Granitic gneiss. (~~~~m~.nt Complex).

"" ~

Official Number Locality

1022 Marapong, Bakgatla Reserve ....

1023 Ramotswadikgomo, Bakgatla Reserve ..

1024 Qodi, Bakgatla Reserve 1025 Modipane, Bakgatla

Reserve ....... . 1026 Kolongkwaneng, South­

ern Kgalagadi district 1027 Shulabompe, Ngamiland

1028 Maitlho a phuduhudu, Bakwena Reserve ..

1029 Moshupatsela, Ngami­land

1030 Moshupatsela, Ngami­land

1031 Jameu, Bamangwato Re­serve

1032 Mmolekae, Bamangwato Reserve .

1033 Sikolane, Bamangwato Reserve .

1034 Mochudi, Bakgatla Re­serve

1035 Rabotsiripa, Bakgatla Reserve

1036 Mochudi, Bakgatla Re­serve

1037 Modipe, Bakgatla Re-serve "

P.891 Schaapkuil, Lobatsi Block ..

?S=:: s-·::-·: :=:-~-=-: :",::,:;~-:..s.

::s:.;:~

._,i~~,",,",~,~

Depth in feet

300

300 141

130

124 200

472

350

201

260

150

300

347

300

200

167

162

-aB:,

Yield G.P.H.

Blank

180 Blank

Blank

600 1,400

660

Blank (35 g.p.h.)

Blank

550

60

4,000

Blank

Blank

1,200

Blank

2,000

.:.... . ..:u: .1BIIlII!;

Depth water

struck in feet

180 & 225

97 & 108 130 & 175

Static water rest level from

surface in feet

170

90 120

455 to 460 436

224 160

(Saline groundwater)

228 112

35 20

78 61

120 90

120 78

.:.:.

""'" :r;:;;;;

Geology

Basement Complex.

Bacoement Complex granitic gneiss. Felsite.

Basement Complex.

Sheared quartzite (Kaaien Beds?). Calcrete (20') greywackes and siltstones

(Ghanzi Beds).

Kalahari Beds (185') and Middle Ecca Series sandstone (Karroo System).

Diabas8.

Alluvium (72'), Quartzites (Ghanzi Beds) ...

'" Granulite and schist (Basement Complex)

Basement Complex granite.

Dolerite.

Dolerite (lOO') and Waterberg System sandstone.

Basement Complex granitic gneiss. and schist.

Waterberg System sandstone with basic intrusions.

Granite and dolerite.

Shales and decomposed dolomite (124') and dolomite (T'rans...-aal Syst.eI8.l.

:::~::':::; .;.-:: _." - ~~

:::';;::::::-;;:-~,.-~"''''- ~,.. '~-.,-.--