world bank documentdocuments.worldbank.org/curated/en/... · table 2: average ph levels soil...

Tanzania Energy Development and Access Project (TEDAP)

P0101645

Environmental Assessment – Annex 2: Geological Investigations

(EA)

Part A (January 2005)

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REINFORCEMENT AND UPGRADING OF DSM, KILIMANJARO AND ARUSHATRANSMISSION UNES AND DISTRIBUTION SYSTEM PROJECT:

Environmental Studies

ANNEX 2:

Geological Investigations

Leonard B. KassanaResearch & Development Department,

Tanzania Electric Supply Company Limited,P.O. Box 9024, Dar es Salaam. Tanzania.

January 2005

Reinforcement & Upgrading of Dar es Salaam, Kilimanjaro And Arusha Transmission LinesENVIRONMENTAL STUDIES - ANNEX 2: GEOLOGICAL INVESTIGATIONS

LIST OF TABLES

Table 1: Grain Size DistributionTable 2: Average PH levels Soil Properties

LIST OF APPENDICES

Appendix 6.1: MapsAppendix 6.2: Test pits logsAppendix 6.3: Laboratory ResultsAppendix 6.4: Photo Records of the Investigation AreaAppendix 6.5: Other relevant literature and correspondence docs

ACRONYMS AND ABBREVIATIONS

CH Inorganic clays of high plasticitykv Kilo VoltMA Moshi-ArushaND Non-DispersiveQDS Quarter Degree SheetpH Negative decinal logarithm of the hydrogen ion activityPi Plasticity IndexTANESCO Tanzania Electric Supply Comnpany LimitedKm KilometersSM Silty sands and sand-clay rnixturesToR Terms of ReferenceTP Test Pit

USCS Unified Soil Classification System (American Society for Testing andMaterials, 1985).

Leonard B. Kassana iiiTanzania Electric Supply Company Limited 1/26/2005

Reinforcement & Upgrading of Dar es Salaam, Kilimanjaro And Arusha Transmission Lines

ENVIRONMENTAL STUDIES - ANNEX 2: GEOLOGICAL INVESTIGATIONS

ACKNOWLEDGEMENT

The author is highly indebted to the following people for the assistance in one-way or the other. Their

logistical support and comments as well, have been helpful in carrying out this task:

Dar es Salaam:

* Mr. K.R. Abdulla - Tanesco, Director Corporate Planning & Research

* Mr. D.E.P. Ngula - Tanesco, Manager Research & Development

* Mr. M. Katyega - Tanesco, Chief Research & Investigation Engineer

* Mr. K. Kabaka - Tanesco, Senior Geologist

* Messrs Mansur, H & Lazimah, J - Tanesco Environmental Engineers

Arusha:* Mr. C.J. Masasi - Tanesco Regional Manager

* Mrs. Dina Msuya - Tanesco Civil Engineer Technician, Transmission Lines

Leonard B. Kassana iv

Tanzania Electnc Supply Company Limited 1/26/2005


EXECUTIVE SUMMARY

This document is an annex to the main report for Reinforcement & Upgrading of Dar es Salaam,Kilimanjaro And Arusha Transmission Lines ENVIRONMENTAL STUDIES. It deals with issuespertaining Geology and in particular soil conditions and its main objective is to obtaingeneral overview of the geological/soil conditions of the project areas.* Ihe proposed corridors for the Moshi - Arusha 132 kV overhead transmission is approximatejy70 km long and the Dar es Salaam transmnission routes are approximately 43 km long.Regionally, the Moshi - Arusha area lies within the Great Eastern African Rift Valley and isdominated by volcanic formations. The transmission corridor traverses east west through southernlower flat lying foot of the mounts Kilimanjaro and Meru. The proposed transmission corridorwas selected to run parallel with the existing 132 kV transmission line from Moshi Kiyungisubstation to Arusha Njiro substation.* The Moshi - Arusha transmission towers will be founded in volcanic sediments mainly consistingof Sandy Silty CLAY and few places have soils mainly composed of Sandy SILT/Silty SAND.* Soil samples taken from Moshi - Arusha Transmission line corridor have pH values slightlyvarying, a bit on the acidic side and largely on the alkaline side. About 80% of the tested soilsamples have PH values greater than 7.0 indicating that the soils are alkaline in nature. Only 20 %of the tested soil samples show acidic nature. By these results, the ground conditions in the Moshi- Arusha Transmission line route are not acidic and therefore it may be inferred that the site posea very less corrosive threat to the transmission towers. During the fieldwork, random visualinspection was conducted on the existing 132 kV transmission towers and corrosive effects werenot observed on the towers.* The Dar Transmissions corridors are located in the coastal plain environment dominated bysuperficial sands of the flat, low lying coastal plain represented by redistributed outwash materialfrom the fault blocks. River alluviums consisting of sands varying from off-white to buff-brownare also found in the corridors. Test on soil pH for the samples collected from Dar corridors showthat the soils specimen are acidic, but the number of soil samples is too small to make a definitiveconclusion.* Due to terrain nature of the transmission corridors and non-dispersive nature of the few samnplestaken from the sites, it is apparently inferred that soil erosion along the transmission is not severe.Control measures for soil erosion will have to be determined on a tower-to-tower case during thedesign/construction phase. At this stage of this report we may not have a suitable blanket solution.* Due to the preliminary nature and time/budget constraints of the study, the Field Resistivitymeasurement for assessing electrical conductivity of the ground, was not conducted during thisperiod and thus it is recommended to be done at later phase of the study/implementation.

Leonard B. KIassana vTanzania Electnc Supply Company Limited 1/2&62005



1. INTRODUCTION

The field investigations for Reinforcement & Upgrading of Kilimanjaro-Arusha Transmission Lines and

Dar es Salaam transmission lines took place between weeks no. 49 and 52 of 2004. This

report gives an account of preliminary findings with respect to geological/soil conditions of

the project area.

The project areas are situated in Northern and Eastern parts of Tanzania for Moshi-Arusha and Dar es

Salaam Transmission routes respectively. The Moshi-Arusha Transrnission Corridor lies between 30

22' S and 30 26' S Latitudes, 36°41'E and 370 19'E Longitudes. The Dar es Salaam transrmission

corridors lie between the following geographical coordinates: 6°43' and 6°56'S latitudes and 39°10'

and 39021 'E longitudes. General locations of the project areas are shown in Figure 1.

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Figure 1: General location of the Project Area

Leonard B. KassanaTanzania Electric Supply Company Limited Page 1 of 8 1/26/2005

Reinforcement & Upgrading of Dar es Salaam, Kilimanjaro And Arusha Transmission LinesENVIRONMENTAL STUDIES- ANNEX 2: GEOLOGICAL INVESTIGATIONS

1.1 Scope of Work

The scope of the assignment was to obtain general overview of the soil and general geologicalcondition of the area so as to highlight preliminary effects of soil erosion with respect toEnvironmental Impact Assessment. Specifically, the scope included:* Scan and traverse along the proposed corridor documenting rock and soil types in general i.e.Overview Mapping.* Zoning and documenting different geomorphologic conditions along the proposed corridor* Spot soil investigations at few selected sites at locations to be determined at the site by thegeologist.

1.2 Methods of Investigations

Senior Geologist, Mr. Leonard B. Kassana of Research and Development Department, TANESCOHead Office, executed all investigations in accordance to the ToR.

The field light investigations consisted of:* Carrying out soil investigations within the selected transmission corridors by test pitting. Soilsamples were collected for laboratory analysis as well* Ground water measurements in the Investigation pits.* Overview Geological Mapping* Literature search relevant to the project.

An overview mapping was based on:* Interpretation of topographic map at 1:50,000 and 1 :100,000 scales* Interpretation of Geological maps, Quarter Degree Sheet (QDS) at a scale 1:125,000* Walkover survey along the proposed transmission corridors

Refer to Appendix 6.1 for maps locating investigation areas.

2. TOPOGRAPHY, REGIONAL GEOLOGY AND SITE GEOLOGICAL CONDITIONS2.1 Kilimanjaro - Arusha Region

2.1.1 Topography

The project area is dominantly covered by volcanic mountain massifs rising abruptly from plateaucountry at about 900 m.a.s.l For Arusha areas, mount Meru raises from about 900 m.a.s.l to thesummit of about 4600 m.a.s.l. and Kilimanjaro rises from about 900 m.a.s.l to the highest peak of5895 m.a.s.l.

In general, the proposed transmission line runs parallel to both existing 132 KV Moshi - ArushaTransmission line and the main Moshi - Arusha road. The line runs almost east west direction southof the high volcanic mountains in Africa, namely Kilimanjaro and Meru. The transmission lines arerunning parallel to the Moshi-Arusha road in the south of the mountains. North of this road, theterrain is of mounded topography formed by Meru lahars while in the south of the road and whereour transmission proposal is running, outwashes from the lahars form a more even plain.Wide spread topographical features are formed by the spread of 'lahars' or cold mudflow in thesouth and southwest of mount Kilimanjaro emanating from Kibo peak and mount Meru.For the further details of the topography the reader is kindly referred to the special QDS covering#42, 56 & 57 and QDS #55.

Leonatd S. KassanaTanzania Electnc Supply Company Limited Page 2 of 8 112612005



2.1.2 Regional Geology

Mt. Meru and Kilimanjaro are younger volcano products of Pleistocene to Recent. According to

Quarter Degree Sheets (QDS) # 55 and the KilimanjaroSpecial QDS, essentially the geology of the

area is consisting of a pile of Neogene volcanic products and some interbedded sediments

accumulated on eroded surface Precambrian metamorphic rocks.

The two volcanoes together with other formations are located on transverse branch of southern

Gregory Rift, part Great Eastern Branch of the Great Eastern African Rift System as shown in figure

2.1.2

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For comprehensive reading on the project geology, the reader is referred to Geological Maps, Quarter

Degree Sheets # 55, 42, 56 and 57.

2.1.3 Soils in the Project Area

The proposed transmrission corridor traverses along lower, flat slopes of the Kilinmanjaro and Meru

mountains in the south. The south side of Mount Meru exhibits some black soils with distinctive

Leonard S. KassanaTanzania Electric Supply Company Limited Page 3 of 8 1/26/200


carbonate concretions. Else where, soils on volcanic rocks show substantial colour variation from redto brown and even grey. In some areas calcareous duricrust zones are found within the project area.Seven test pits were dug along the corridor to assess the lithological conditions. Field lithologicaldescriptions of these superficial deposits show domninantly that the sediments are Clayey SILT/SiltyCLAY with occasion sand pockets. For field details please refer to Appendix 6.2.

Large section where the transmission traverses is flat and only in few areas there are gentle slopes arrdexamnination of the existing 132 KV transmission towers which were built in earlyl980s showed nosign of erosion effects. Thus due to low gradient nature of the corridor, the corridor is naturally facingno severe erosion.

Due to the preliminary nature of the investigation could not be well assessed but all test pits dug incorridor were dry and showed no sign of Groundwater. Volcanic rocks that may be porous andvesicular in nature imnnediately underlie the superficial deposits. The former is full of pore spaces andthe later is full of many cracks and vesicles, so water is easier to get through the ground. So a highpercentage of rainfall is absorbed into the ground. But since our excavation is shallow, we don'texpect to encounter ground water during excavation except where a stream depression is crossed.2.2 Dar es Salaam Region

2.2.1 Topography

In general, Dar es Salaamn is a coastal region whose widest topography lies between 0 m.a.s.l and 120m.a.s.l. However Pugu hills who constitutes a small percent of the region rises to about 300 mna.s.lforming the highest land in the region. The proposed transmission corridor traverses in a terrainwhose altitude ranges between 15 and 60 m.a.s.l.

Major rivers within the project are Kizinga, Mzinga, Msimbazi,, Ubungo, Sinza and Mlalakuwa alldraining towards Indian Ocean in the north easterly direction. Dar es Salaam Harbor is a Northerlypart of River Mzinga mouth at the Indian coastline. The Dar es Salaam harbor is thought to have beenformed by erosion effects of Mzinga and Kizinga rivers further deepened by tidal scour.Further details for the topography may be found in the QDS 186.

2.2.2 Regional Geology and Soils

The main geological formations of Dar es Salaam region, in brief summary, are composed of:* Pugu Kaolinitic Sandstones, which are fine to medium grained and off-white in colour. These arefound in the south west of Dar es Salaam with an SW-NE trend line.* Clay bound sands is another geological formation overlying the sandstones. The sandstones arereported to be of, probably, Mio-Pliocene age and they are semi-consolidated.* Reef limestones occur at several localities in the region. The age of this formnation is assumed tobe Mio-Pliocene.* Superficial sands of the flat, low lying coastal plain represented redistributed outwash materialform the fault blocks. East of Pugu, the sands are clean and off-white but elsewhere they are buffto brown.* River alluvium consisting of sands varying from off-white to buff-brown. The fine grades tend tobe dark due to presence of admixed organic matter.

According to QDS 186, two types of faults dominate the region. The most dominant set is the onewhose trend line varies between NE to N. This seems to control the major rivers in the region. Secondset is the one apparently controlling the coastline in the region trending in the SE-NW direction.These faults are considered to be of recent age geologically. The reader is kindly referred to QDS 186for further details of the regional geology.

Leonard B. KassanaTanzania Electnc Supply Company Limited Page 4 of 8 1/25/2005



3 LABORATORY SOIL INVESTIGATION

Soil samples were collected from both Moshi -Arusha and Dar es Salaam Transmission Lines

corridors for the purposes of carrying out laboratory analysis. Investigation areas where soil samples

were collected are shown on maps enclosed in this report in Appendix 6.1. The following test

categories were ordered:* Grain size distribution for soil classification

* PH levels for assessing acidic condition of the soils

* Pinhole tests

The laboratory investigations were carried out at the Soil Laboratory of the University of Dar es

Salaam.

3.1 Methods

All soil investigations for the above mentioned tests were carried out in accordance to the known

international standards. The following British Standards were employed during the testing:

* BS 1377 for Pinhole tests* BS 1377: Part II: 1990 for Grain size distribution

* BS 1377: Part III: 1990 Test #9 for PH levels determination

3.2 Results & Discussions

Sieve Analysis results indicate that the soils in Moshi - Arusha Transmission Line corridor are

composed largely of Sandy Silty CLAY and few places have soils mainly composed of Sandy

SILT/Silty SAND. This means that the behaviors of soils in the project area are of varying nature

corresponding to the behaviour of the composite soils. Generally, earthwork during the project

execution should be well taken care of, otherwise piles of earth could easily be washed away and

therefore increase turbidity/sediment loads within the water courses within the vicinity of the sites of

the project activities. Refer to Table I and Appendix 6.3 for details on Sieve Analysis.

Laboratory soil analysis (Table 2 and Appendix 6.3) shows that soil samples taken from Moshi -

Arusha Transmission line corridor have PH values slightly varying, a bit on the acidic side and largely

on the alkaline side. About 80% of the tested soil sanples have PH values greater than 7.0 indicating

that the soils are alkaline in nature. Only 20 % of the tested soil samrples show acidic nature. By these

results, the ground conditions in the Moshi - Arusha Transmission line route are not acidic and

therefore it may be inferred that the site pose a very less corrosive threat to the transmission towers.

During the fieldwork, random visual inspection was conducted on the existing 132 kV transmission

towers and corrosive effects were not observed on the towers.

Only two samples were collected from Dar es Salaam Transmission Line routes and tested for pH

levels. The results indicate that the soils are acidic but with only two samples it is difficult to mnake a

definitive conclusion on acidic conditions coverage on the ground in the area.

However, due to laboratory apparatus malfunctioning, Pinhole tests were not completed as per our

order that was submitted to the Soil Laboratory vide letter with ref. DCPRIMRD/CRIE/9 dated

December 14, 2004. Only two Pinhole tests were successfully done and showed that the soil samples

were non-dispersive soil (ND). See the results in Table 3 and Appendix 6.3.

Leonard 8. KassanoaTanzania Electric Supply Company Limited Page 5 of 8 1/262005

Reinforcement & Upgrading of Dar es Salaam, Kilimanjaro And Arusha Transmission LinesENVIRONMENTAL STUDIES - ANNEX 2: GEOLOGICAL JNVESTIGATIONS

Table 1: Grain Size Distribution for both Moshi - Arusha and Dar es Salaam Transmission Lines# Location Depth of USCS Soil Description % % % %Sampling in Symbol Clay Silt Sand GravelmI TPI -MA 0.6- 1.7 CH Sandy Silty CLAY 52 43 5 02 TP2 - MA 0.0-0.8 CH Sandy Silty CLAY 47 36 10 7-3 TP4-MA 0.3-0.6 SM Clayey gravelly 2 21 58 27

Silty SAND4 TP6-MA 2.0-2.5 SM Ciayey Sandy- 7 50 43 0

SILT5 TP7 - MA 0.6-1.7 CH Gravelly Sandy 57 31 10 2

Silty CLAY6 MLIMANI-CITY 0.0-0.5 CH Gravelly clayey 15 15 77 3PROJECT. DAR Silty SAND7 Buza Kipera S/S - Clayey Silty 8 11 81 0Mbagala, DAR SAND

Table 2: PH Levels

# Location Depth of USCS Soil Description. AverageSampling in m Symbol PHI TPI - MA 0.6- 1.7 CH Sandy Silty CLAY 6.362 TP2 - MA 0.0-0.8 CH Sandy Silty CLAY 8.543 TP4-MA 0.3-0.6 SM Clayey gravelly Silty SAND 7.154 TP6 - MA 2.0-2.5 SM Clayey Sandy SILT 9.565 TP7 - MA 0.6-1.7 CH Gravelly Sandy Silty CLAY 7.636 MLIMANI CITY PROJ 0.0-0.5 CH Gravelly clayey Silty SAND 6.15DAR7 Buza Kipera S/S - Clayey Silty SAND 7.07Mbagala, DAR

Graphical representation and other details are found in the Appendix 6.3.

Table 3: Pinhole test

Sample no. Depth of Sarpling ClassificationTP2 0.0-0.60 ND4TP 7 0.0 - 1.30 ND 4

Leonard B. KassanaTanzania Elecd nc Supply Company Limited Page 6 of 8 1/26/2005



4 CONCLUSIONS AND RECOMMENDATIONS

* The proposed corridors for the Moshi - Arusha 132 kV overhead transrission is approximately

70 km long and the Dar es Salaam transmission routes are approximately 43 km long.

* Regionally, the Moshi - Arusha area lies within the Great Eastern African Rift Valley and is

dominated by volcanic formations. The transmission corridor traverses east west through southem

lower flat lying foot of the mounts Kilimanjaro and Meru. The proposed transmission corrid6r

was selected to run parallel with the existing 132 kV transmission line from Moshi Kiyungi

substation to Arusha Njiro substation.* The Moshi - Arusha transmission towers will be founded in volcanic sediments mnainly consisting

of Sandy Silty CLAY and few places have soils mainly comnposed of Sandy SILT/Silty SAND.

* Soil samples taken from Moshi - Arusha Transmission line corridor have pH values slightly

varying, a bit on the acidic side and largely on the alkaline side. About 80% of the tested soil

samples have PH values greater than 7.0 indicating that the soils are alkaline in nature. Only 20 %

of the tested soil samples show acidic nature. By these results, the ground conditions in the Moshi

- Arusha Transmission line route are not acidic and therefore it mnay be inferred that the site pose

a very less corrosive threat to the transmission towers. During the fieldwork, random visual

inspection was conducted on the existing 132 kV transmission towers and corrosive effects were

not observed on the towers.

* The Dar Transmissions corridors are located in the coastal plain environment dominated by

superficial sands of the flat, low lying coastal plain represented by redistributed outwash material

from the fault blocks. River alluviums consisting of sands varying from off-white to buff-brown

are also found in the corridors. Test on soil pH for the samples collected from Dar corridors show

that the soils specimen are acidic, but the number of soil samples is too small to make a definitive

conclusion.* Due to terrain nature of the transmission corridors and non-dispersive nature of the few samples

taken from the sites, it is apparently inferred that soil erosion along the transmission is not severe.

Control measures for soil erosion will have to be determined on a tower-to-tower case during the

design/construction phase. At this stage of this report we may not have a suitable blanket solution.

* The test results at this stage are only indicative as they are not very elaborate and details are not

adequate due to the preliminary nature of the study. Further and detailed sampling should be done

to have more standard classification tests in the next stage of the project. Such tests may give

additional qualifying data for the soils from the site.

* Due to the preliminary nature and time/budget constraints of the study, the Field Resistivity

measurement for assessing electrical conductivity of the ground, was not conducted during this

period and thus it is recommended to be done at later phase of the study/implementation.

Leonard B. KassanaTanzania Electric Supply Cornpany Limited Page 7 of 8 1/282005


6. REFERENCE

* Anders, R., et al 1972: Soil Erosion and Sedimentation in Tanzania, University of Upsalla, Clarkand University of Dar es Salaam.* British Standards Institution, 1981: Code of Practice for Site Investigations, BS 5930:1981* Geological Survey Division of Tanzania, 1983: Quarter Degree Sheet (1:125,000) # 55, Arusha,I st Edition.* Geological Survey Division of Tanganyika, 1965: Special Sheet (1:125,000), Kilimnanjaro -Moshi, covering QDS #42, 56 & 57.* Geological Survey Division, Ministry of Industries, Mineral Resources and Power, 1964:Explanatory Notes on the Geological Map of Kilimanjaro* Kassana, L.B, 1990: Geology of Pugu Kaolinitic Sandstone, Kisarawe, Tanzania. Unpub. BSc.Thesis, Geology Departrnent of the University of Dar es Salaan. 32 p* Survey and Mapping Division of Tanzania, 1965: Topographic Map 1:50,000 Sheet #52/2, Series,Edition 2-TSD/OSD.

Leonard B. KassanaTanzania Electric Supply Company Limited Page 8 of 8 1/26/2005

Reinforcement 4 Upgradmng Of Dar es 5alaam, Kilimanjaro And Aru5ha Transmis5ton Unes

ENVIRONMENTAL SIUDIES - ANNEX 2: GEOLOGICAIJSOIL INVESTIGATIONS

APPENDIX 6.1: MAPS

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Reinforcement 4 Upgrading Of Dar e5 5alaam. Kilimarijaro And ArUsha Transmission LbncsENVIRONMENTAL STUDIES - ANNEX 2: GEOLOGICALlSOIL INVESTIGATIONS

APPENDIX 6.2: TEST PIT LOGS

Reinforcement & Upgrading Of Dar es Salaam, Kilimanjaro And Arusha Transmission Lines

ENVIRONMENTAL STUDIES - ANNEX 2: GEOLOGICAIJSOIL rNVESTIGATIONS

APPENDIX 6.2: TEST PIT LOGS

AA: MOSHI - ARUSHA 132 KV TRANSMISSION LINE

NB: All test pits were excavated within the existing Moshi - Arusha 132 KV Transmission

way leave

TP 1

Depth (m) Lithological Description Sample Remarks

from top

0.0 - 0.4 Dark Grey clayey SILT, with vegetation roots 0.60 - 1.70 GW Dry

0.4 -1.1 Brownish Grey clayey SILT All soils arevolcanicsediments

1.1 - 1.7 Yellowish Brown SILT, hard clump

TP 5


from top

0.0 - 0.3 Hard, Yellowish Grey clayey SILT #1:0.21-0.51 GW = Dry

0.3 - 51 Consolidated soil - Yellowish grey hard #2: 0.0-0.21 All soils are

crust with whitish spots volcanicsediments

TP 6


from top

0.0 - 0.6 Yellowish grey, loose, clayey SILT 2.0-2.5 River bank cut atKiyungi S/S

0.6 - 1.20 Blackish grey, loose, fine SILT All soils areALLUVIAL sediments

1.20 - 2.5 Slightly yellowish grey, very loose,

clayey SILT

TP 2


from top0.0 - 0.6 Cobles, gravels in black cotton soil 0.0- * Alluvial clay deposits

matrix 0.60 with cracks seen on

0.4 - 1.0 Highly (grade IV) Weathered the surface.

volcanic rock * Cobbles aresubangular

Leonard B Kassana 1 of 3

Tanzania Electric Supply Company Limited 1/2f2005

Reinforcement & Upgrading Of Dar es Salaam, Kilimanjaro And Arusha Transmission LinesENVIRONMENTAL STUDIES - ANNEX 2: GEOLOGICALUSOIL INVESTIGATIONS

TP 3: Located at 30 m north of angle tower # MA I I IDepth (m) Lithological Description Sample Remarksfrom top0.0 - 0.50 Dark Brown, medium dense clayey 0.0 - 50 * Rock lump in filledSILT with calcitic material0.50 - 1.30 Highly weathered (grade [V)

volcanic rock

TP 4: Located 300 m west of River Sanya on the right hand side bank, flash flood areaDepth (m) Lithological Description Sample Remarksfrom top0.0 - 0.8 Grey, loose, dusty sandy SILT 0.0-0.8 * Gravels are sub angular0.8 - 1.1 Gravel in Silty matrix

TP 7: located 30 m north of tower # MA 12, top of a ridgeDepth (m) Lithological Description Sample Remarksfrom top0.0 - 1.30 Reddish Brown firm clayey SILT 0.0-1.30

(Lateritic Soil)

Leonard B. Kassana 2of 3Tanzania Electnc Supply Company Limited 1/26/2005


ENVIRONMENTAL STUDIES - ANNEX 2: GEOLOGICALUSOIL rNVESTIGATIONS

BB: DAR ES SALAAM CITY 132 KV TRANSMISSION LINES

BB1:FZIII - MBAGALA s/s 132 KV TRANSMISSION LINE

TPD 1: about 150 m west of the proposed angle tower TW 14, logging done at the road cut of

TAZAMA pipe access road.


from top

0.0 - 1.80 Reddish Brown, sof to firm Silty

CLAY

TPD 2: located at the proposed Buza/Kipera (Yombo) 132/33 kv substation


from top

0.0 - 0.30 Grey silty SAND

0.30 - 1.0 Yellowish Grey silty SAND

BB2: UBUNGO - MIKOCHENI 132 KV LINE

TPD3: located on the left bank of Ubungo River at the Sam Nujoma road bridge. All soils are

alluvial deposits


from top

0.00 - 0.25 Dark grey clayey SILT

0.25 - 1.00+ Grey, medium SAND

TPD4: Excavation pit of the Mlimani Holdings Project construction site


from top

0.00 - 1.40 Yellowish Grey, clayey coarseSAND

1.40 - 2,00 Dark grey sandy clayey SILT

Leonard B. Kassana 3 of 3

Tanzania Electric Supply Company Limited 1/26/2005

Reinforcement 4 Upgrading Of Dar e5 Salaam. Kilimanjaro And Arusha Transmission LinesENVIRONMENTAL STUDIES - ANNEX 2: GEOLOGICAJJSOIL INVESTIGATIONS

APPENDIX 6.3: LABORATORY TEST RESULTS.

SOIL pH TEST

COMMITTEE OF THE INTERNATIONAL SOCIETY OF SOIL SCIENCES

PROJECT:- Tanesco Power LinesDate:- 27 December, 2004

SAMPLE TP I TP2 TP4 TP6 TP7 MLIMANI pit MBACALA

No. 0.60 - 1.70 0.00 - 0.60 0.00 - 0.80 2.00 - 2.50 0.00 - 1.30 KIBURUGWA PIT

0.00 -0.50

Mass of soil 30 30 30 30 30 30 30

used

Volume of 75 75 75 75 75 75 75

distilled waterused mlsSoil to Water 1:2.5 1:2.5 1:2.5 1:2.5 1:2.5 1:2.5 1:2.5

RATIO

measured 6.3i 6.35 6.36 7.15 7.16 | 73 0 9.259.24 9 7631764| 7.3 6.1669 6. 7.17 7.03

Average pH 6.36 8.54 7.15 9.56 7.63 6.15 7.07

value

Temperature 29.7 29.8 29.7 29.8 29.8 29.8 29.8

degreescngrde - -:c-, -

PIN HOLE TEST.

BS 1377: Part 5: 1990

SAMPLE No. SAMPLING DEPTH CLASSIFICATION FROM PIN HOLETEST

PIT No.2 0.00 - 0.60 ND4

PIT No. 7 0.00 - 1.30 ND4

TESTED AND REPORTED BY:A J.MBUYAH i Dje of Tunpoabon& Gecmica-

fa oCMh En& & The BLh Exvizonrnz_4c Colpf EWeznn & Thhual

WUyivk of Dar-eUP O. Box 35131

%-. . - .

C SILT IM omws. COfaLn100 -i -

zX 0

|- 80 - T 2.00

w-02

0PI0.0T 0.70 CH SAD lr LY 2 4

30.0 10 0.00 100.00

mz

- -4 TP 6 200 TO 2.50SM CLAYEY PAND TICL E SI -IN mm4 ta 5; E- 4- TP 1-ETH06 - 1.0meesT2DE H 0.0 - .6mts-A- T 4DPH00- 0.0 ete - - - T6DET2.00-.0mte

LOCATIONP UO. Cax CO51S3NC

3\^ -P

O.30T00.6 SM- C.YYRVLYITSN - 1 8

0.oxx5340~~

EI- 0.0 ' 0 01

.0 '1.0'100

CzAY SILT WmC

COSZLIS

100 1 -

0

|-+ P

EPH00

- 1.0C)e

IIAIDPH .0O5mrSMAAA ee

800

o I

NO, . d6 - -

0 - -

20

ii 0000.01 0.10 1.00 10.00 10.oo

PARTICLE SIZE IN mm

-4- -TP7 DEPTHO.O00- 1.30 memr - -MLIMANI DEPTH 00- 0.50mvetrs -- MBAGALA- metres.

LOCATION Uc. CC.COSTEY

SAMPLE No. DEPTH OF SAMPLING USCS SOIL DESCRIPTION 6 -de % %% l

No, SYMBOL die dio .dw CLAY SILT SAND GRAVEL

5 4P70.60 TO1.30 CH4 GRAVELLY SANDY SIL TYCLAY 57 31 10 o

6 MLMNI 0 TOc1 0.50 C14 GRAVELLYCLAYEYSILTYSAND - 15 15 7PY tyot C* ft & I Buik

7 7iMBANG - Su eLAYEY SILTY SAND 1 8 = O73

P 0esSaaa B -35131

Reinforcement 4 Upgrading Of Dar es 5alaam, Kilimanjaro And Aru5ha Transmt55ion Line5ENVIRONMENTAL STDIES - ANNEX 2: GEOLOGICAJSOIL INVESTTGATIONS

APPENDIX 6.4: PROJECT PHOTO ALBUM


ENVIRONMENTAL STUDIES - ANNEX 2: GEOLOGICAUSOIL INVESTIGATIONS

APPENDIX 6.4: PROJECT PHOTO ALBUM

AA: MOSHI - ARUSHA 132 KV

Km 00: View showing LHS bank of the

Lukaranga River. In the background the Moshi-

-,. - ., Arusha tower no. I can be seen

- Km 3.0: View to the East

-Km 3.3: View to the East

Leonard B. KassanaTanzania Electric Suipply Company Limigted

1/26/2005

Reinforcement & Upgrading Of Dar es Salaam, Kilimanjaro And Arusha Transmission LinesENVIRONMENTAL STUDIES - ANNEX 2: GEOLOGICAL/SOIL INVESTIGATIONS

Km 6: View to the East

- .

--

Kmn 6: View showing a local ladycollecting 'Magadi' - Soda

-: FBicarbonate

.- ' , ---


e

-.

LAA6

Leonard B. Kassana jjTanzania Electric Supply Company Limited

1/26/2005


ENVIRONMENTAL STUDIES - ANNEX 2: GEOLOGICAL/SOIL INVESTiGATIONS

- - --

Km 24: View to the Southi

.- ! o

AA7-

-~~ -,X,

V'sS

Km 24: View into TP 4

Km 24: View to the tower

footing

Leonard B. Kassana iii

Tanzania Electnc Supply Company Linited 1/2&2005


--Km 30: View to the West.

IAAI

Km 34: View to the West

- L. -


AA12

Leonard B. Kassana iVTanzania Electric Supply Company Limited 1/26/2005


ENVIRONMENTAL STUDIES - ANNEX 2: GEOLOGICALUSOIL INVESTIGATIONS

Kin 34: View into the TP 3

Km 58: View to the West

: - --

Km 58: View showing theexpansive ground

Leonard B. Kassana v

Tanzania Electnc Supply Company Limited 1/26/2005


"T

Km 58: View into TP 2

~416 &

L -.*

___ __ . -

( W - Km 72: View to the East

A 17

Km 72: View into TP I

Leonard B. Kassana viTanzania Electnc SUPPIY ComPany Limrted 1/262005


ENVIRONMENTAL STUDIES - ANNEX 2: GEOLOGICAL/SOIL INVESTIGATIONS

BB: DAR ES SALAAM TRANSMISSION LINE CORRIDORS

BB 1: UBUNGO - MIKOCHENI LINE

~w-.

Km 0.3: View showing thealluvial sand on the RHS of Sinza

River

, . ,

PlateBBI-1 *" -

Km 3.3: View at Mlimani City

Project construction pit showing

,.. erosive effects on the soil strata

Kin 3.3: View as plate BB 1_2

-~ showing a wide view of the

____ _construction pit

l .- *F-,

Plate ; .K Vl

Leonafd B. Kassan'. viiTanzania E;ectrc Supply Company Limited

1/2/2005


BB2: FZHI SS-MBAGALA SS LINE

Km 0.0: View looking northerly.. -direction showing the Factory

~ ~Zone Eg 132/33 kV substation

Plate BB2-1

-A:'

w~~~;,~K 0sS' * 1 n.0: View looking southerlydirection showing the 132 kV Feederoutlet Factory Zone m 132/33 kVsubstation to

Plate BB2-2

I ~

.-.

Km 9.1: Looking southeast.- direction showing terrain and

vegetation where the line traverses

Plate BB2-3

Leonard B. KassanaTanzania Electric Supply Cornpany Limited Vil12&2005


ENVIRONMENTAL STUDIES - ANNEX 2: GEOLOGICALUSOIL INVESTIGATIONS

Km 9.1: Looking northwesterly

'3 direction showing terrain andJ -vegetation where the line traverses

PlateBB24t

View at kml 10.0: Looking

condition of the line traverse

Plate BB2-5

s~~~ ~ ~ -z ' ."t:!.

* : (..

~< - - =Km 12.0: Looking west showing

i . - . h1 . i terrain condition of the line

-; - K. traverse

Plate BB2 - -

Leonard B. Kassana ixTanzania Electnc Supply Company Limited

1R6R005


. ~,/ I,/\/

hi 'View at Mbagala substationlooking north showing the linetraverse and terrain conditions

Plat BB-7

View at Mbagala existingsubstation looking east direction

-- -

Plate BB2 - 8

Leonard B. Kassana XTanzania Electric Supply Company Limited 1/26/2005

Reinforcement 4 Upgrading Of Dar es 5alaam, r.limanjaro And Aru5ha Transmis5ion Lines

ENVIRONMENTAL STJDIES - ANNEX 2: GEOLOGICALVSOIL INVESTIGATIONS

APPENDIX 6.5: OTHER RELEVANT LITERATURE

' I A I t.} Vt~ ~Ie.s 2Ministry of Iudtnstries, Mineral Resources and Power- (Geological Survey Division)

~k:~i~ IExplaiiatory Notes'. ''on

tlle"* Geological Map of Kiliiiiaiijaro

- # , ;- ; I ,, * *

PREFACE

The Sheffield University Kilimanjaro Expedition began the mapping e

mountain in 1953 with the assistance of the Geological Survey of Tanganyika.

project was under thc leadership of Mr. W. H. Wilcockson and included N '

Wilkinson, Dr. C. Downie and Dr. D. W. Humphries. Officers of the Geol,

Survey attached to the Expedition were N. J. Guest, G. P. Leedal and D. N. San- 1.

-During the first season a general reconnaissance was carried out making u f

early German topographical maps of the mountain.

The memnbrs of the Expedition continued work on the mountain in 195, r

the preliminary -trological work bad.indicated the general distribution of lava

from the volcanic centres. Prof. L. R. Moore and Dr. R. Neves then joinec

Expedition.

4 To complete the area of the quarter degree sheets 42. 56 and 57 rapid m:

on the plains and lower slopes in the neighbourhood of Moshi was compl. n

1963 by E. W. Hanley and G. R. Orridge of the Geological Survey Division r -

the extreme north-west by D. N. Sampson.

The geological map has been prepared by Dr. C. Downie and Mr. P. Wilki

The final completion of the map was held up until the 1:50,000 contoured

based on air photographs were available. The compilation from this scale and I

draughting and checking has been carried out by H. E. Empson, Chief Draugh:

of the Geological Survey Division.

A full geological account is in the final stages of preparation by memb.

the Geological Department of Sheffield University. Meanwhile it is felt apprn,

that the results of the mapping should be issued in the 1:125,000 geological p

series being published by the Tanganyika Government. The following accour

Mir. P. Wilkinson, Dr. C. Downie and other members of the expedition provides a

minary description and summary of the history and petrography of this f.

mountain. Brief descriptions of the economic and watcr supply aspects of the gi

have been added by officers of the Geological Survey.

A number of papers have already been written on Kilimanjaro by memN i

the Expedition and these are listed at the end of this account. They do not. hox'

constitute a full bibliography of geological work done in this area.

Dodoma, J. W. PALtisrER.

April, 1964 Conmmisioner for Grologic,,I S

CONTENTS-

PHYSIOGRAPHY .... . ... ... ... . ...

GLACIAL DEPOSITS . .. ... ... ... ... ...

GEOLOGY ... ... .. . ... ... ... ... ... ...

PRECAMBRIAN ... ... ... ... ... ... ...

NEoENE ... ... .. ... ...-.Shi .... ... ... .. . ....

- 01. Molog group ... ... ......- ... 3Maweaizi ... ... ... ... ... ..... ..

The Neumtann Tower group............ ... .. 3The Mawenzi grouip 3

Kibo ... ... ... ... ... ... ... ... ... 3The lower trachyandesite group ..... .... ...The Lava Tower trachyre group .... ........The lower rectangle porphyry group ... ... .......

The upper trachyandesite group and the upper rectangle porpl

group ..... ... .. .. ...

The rhomb porphyry group ........ ... .... ...

The Lent group ........ ... ... ...

The small-rlornb porphyry group ... jAnalcime syenite ... . .

Kibo "lahar" ... ... .

The Caldera Ri;m group . 5

The Inner Crater group

Intrusions . . . . . ..

Parasitic Cones ... ... ... ... ... ...The Saddle zone

The Roinbo zone ..

Kilema zone. ...

Kibongoto zone ........ .. ... ... ...

Shira and Lagun,ishera zones . .

Present Volcanicity ...... ... ... .. ... ......

Meru "lahar" ... ... ...

Alluvium ... ... ...

Amboseli lake beds ......... ... ...

Calcareous tulTaceous grit ...

Red soils ... .. ...

Wind.blown sands.......

Rr,IONAL SIRUCIURAL FEA1URI.SVOLCANo-TrCTONIc Fr.ATUIRlS

ECONOMic Gr.OLOGYSELECTED BinLIOGRAPIIY . ... ...

PHYSIOGRA fKilimanjaro, which occupies most of this sheet and spreads into adjoining ones,

is a volcanic mountain massif rising abruptly from plateau country at about 3,000 to4,000 feet above sea level to culminate on Kibo in Uhuru Peak, 19,340 feet, the highestpoint on the African continent. The plain-on which the volcanic pile accumulated is awarped and faulted erosion surface the age of which is still uncertain.

Despite its near-equatorial position, the great height of the mountain has caused theglacierization of the Kibo peak above about 15,000 feet: Six glacial episodes have beenrecognized of which the third was the most extensive and included the glacierization ofMawenzi and to lesser extent of Shira as well as Kibo. The earlier of these glacial epi-sodes took place during the activity of the volcanoes as shown by the presence of tillitesunderlying lava or pyroclastics, and have continued since the centres became extinct.Terminal momines are found as low as 10.000 feet on Mawenzi and Kibo. Recentclimatic change, however, has shifted the perrnanent snow-line above the summit leveland the glaciers are now recedini rapidly, leaving lateral and terminal moraines whichform a distinctive feature of the topography. The great altitude also leads to strikingcontrasts in vegetation. A rough zoning of the mountain is as follows: (a) Ice andAlpine Desert, above 13,500 feet; (b) Heath or Moorland Zone from about 10,000 to14,000 feet with giant senecios, lobelias and Erica spp.; (c) Mountain Rain Forest Zone,6,500 to 9,500 feet; (d) Cultivated Temperate Zone, from plain level to about 6,500feet with coffee, bananas, wheat, maize; (e) Plain at 2,500 to 4,000 feet, semi-arid steppe.

The drainage pattern is, in a general way, radial from the three major centres andrivers cut deep gorges into the flanks. Water-flow is seasonal in the north and east andpasses, by way of the Tsavo River, into the Athi (Galana) River system. Inthe extreme north-west the intermittent drainage flows into the dischargeless basin ofLake Amboseli. The rivers of the west and south drain into the headwaters of thePangani River.

Widespread topographic features are formed by the spreads of "lahar" or coldmudflow in the south and south-west, emanating from Kibo and from Meru, aprominent extinct volcano which lies to the west.

In the south, at heights of about 2,500 feet, lie the extensive alluvial plains of theUpper Pangani and its tributaries, and in the north the south-westem parts of theAmboseli Basin appear as widespread alluvial and lacustrine deposits at heights ofabout 3,700 feet.

GLACIAL DEPOSITSAbove the forest level and at heights between 11,000 and 14.000 feet, terminal

moraines belonging to the last glaciation are conspicuous on the flanks of Kibo andMawenzi. Behind them the corresponding lateral moraines follow the ridges up toabout 15,000 feet. The enclosed area is richly endowed with glacial phenomenaincluding cirques, glaciated pavements, boulder-trains, crag and tail, roches mo1ltonn&es.Outwash gravels, almost entirely cover the Saddle area. Sets of retreat morainesare sometimes present and more recent moraines exist near the glacier snouts on Kibo.

Outwash sands and gravels cover wide areas of the flanks notably north-westand south of Kibo and south of the Saddle. In places they extend down to below9,000 feet.

GEOLOGY

Essentially the geology consists of a pile of Neogene volcanic products and someinterbedded sediments accumulated on an erodedl surface of Precambrian metamorphicrocks.

Pxr.CAMNIRIAN

Within the boundaries of the sheet therc are only a fesn restricted otut-crops of Precambrian rocks, all of whiichi have been assigned to the Usagaran of theMozambiquian orogenic belt. These outcrops represent the tops of inselbergs on thepre-volcanic surface and continue the topographic trends of the North Pare andLelatema Mountains in the south.

*north-west comner of the sheet biotite gneiss forrr small hill and, east ciAl Moo roup.-On- the north-western flanks of the mountain, belos,:rystalline limestone appears as a small outcrop. -. the south-west four occurs a group of olivine basaltic and trachybasaltic lavas which appcar ipresent the northern foothills of the Lelatema Escarpment. High-grade one of the earliest eruptive episodes of the mountain and may havc been dl-ti.,nts are here exposed and include garnet-quartz-feldspar granulite, quartzite, the early Shira centre,iu'ianite granulite (khondalite), dolomitic marble, calcite-diopside marble and..olite-homnblende-quartz 'granulfte. A small is-olated outcrop of crystalline- Mawenzi.-The highly eroded rocky mountain Mawenzi, with its binlcrsin the foothills. -at H-ans Meyer Peak, 16,896 feet. is a complex erosion residual between ii :I

t ouh-est he ~tcrps roun Kiumb incudequatzo-eldpatic ganuitecornies. The most important of ihese corries lies on the east at the bet-.cride and/the botcrops arouie ndis aifnd iuncflude spartzafndsahomlnic grnuieg Great Barrancoi, a 4,000-foot gorge whith offers the longest and most continuo..knde Land/or bidgotsite, o biotitegeis and quartz-feldspa andis biotitic quartzo- through the mountain. Mawenzi is a complex volcano with two majc r.heaeaRigcosssobittanhobedenes,visible, giving rise to two groups of volcanic rocks. Both centres have bCL %t,gneiss and smri-icalcareous gneiss. In the two hills north-west and north- since the early Pleistocene.

Laterna, retrogressive homnblende-hyperthene gneisses and granulitesi showing-ipient migmatization are found. These -occur'rences in the south-east lie a -I The Niuman'n Tower group comprises a succession, mainly of lavas, stii :1north of the North Pare Mountains, In general, the foliation of all these )following range of rock type: ankaramite--olivine basat-asphyric and feld' r1.:.s NNW.-SS. with an inclination to the ENE. at 35-45'. olivine trachybasalt and trachybacalt. The lavas dip out from a complex !

an agglomeratic infilling and intrusive bodies, situated at the Neumann Too't IINmEoNEe lavas represent the earliest visible activity of Mawenzi, and in the upper p. f:

cieo h omneeto ocnct sucran ute ot nThree Kings' Valley and-in the Great Barranco, where they form the entire %s'..cc o earles knowmnceogent o volcankicys haverbeen. da rthedrb isortopicn they are seen to be overlain by lavas of the Mawenzi group. To the sou .14 I.3 ealeto 'knillown. yeasold,e namely,ic ofv Mieene dage, The eriesotopi Great Barranco the Neumann Tower lavas occupy the whole south-east M ;13 o 1 mllin yar ol, amey, f iocneage Th erlistMawenzi but (heir full extent is much obscured by later parasitic I: no volcanics can only be dated as Mio-Pliocene and activity has continued blanketing forest. Thus, although their distribution is probably extensive,i'csoeeinto Recent times with diminishing frequency and importance. with lavas below the forest line is conjectural,now limited to local fumnaroiles. The early history is little known because of The Mawenzi group is so named because all the principal peaks of Nft-.ve cover of younger extrusives. From an early stage, activity has been built of. its members. It is a sequence of effusions, including considerable a: .t~.isd around three major centres, which now correspond to the three main pyroclastic rocks, showing the following range of types: olivine trachyt-I.:summits of Shira, Kibo and Mawenzi, The structures of these three trachybasalt--olivine trachyandesite and trachyandesite-basalt---andesite. i~noes mutually interfere.to form a high massif with a pronounced WNW.- characteristic varieties are feldsparphyric and carry numerous phenocrysts of Si.L

catin. umerus araiticcons frm cnspcuou zoes longcerainbytownite with a thin platy habit (length/thickness ratio up to 20-1): they r. ~I:ns.one inch across, In the central region the lavas are often con :C;i-Shira, the oldest centre, is a relatively simple strato-volcanic cone with a brecciated by flow and may be mistaken for pyroclastic rocks. The lava-br,:d crater. Topographically, it forms a plateau 12,000 feet high, rimmed at tuffs, especially the latter, thin rapidly away from the centre. The vents resrimargn b a nrthsout rige treeanda haf mles ongof wichthethese out-pourings have been identified as plugs of syeno-gabbro grouped asi-nt, Klure Peak, is 13,030 feet high. A shorter ridge bounds the south side. of the Great Barranco and in the South Peak.

th and east the structure has been reduced by erosion and buried beneath:,ions from Kibo. Mawenzi and Neumann Tower lav'as extend down the slopes on to r;crossing' into Kenya and are exposed in the wsalls of Lake Chala;, the group,trne is built mainly of lavas, although some pyroclastics are present. The been separated in these regions.

Ickasscitios ae een -A conspicuous feature of the structure is the occurrence of about 601"tmite < olivine basait-trachybasalt-trachyandesite compositions similar to the lavas. They average between two and three 1basaitenephlinte.and are relatively hard and give rise to pinnacles and ridges. Two sets of*lower exposed part olivine basalts are important, but in the upper part arrangcd radially to the Neumann Tower and Mawen7i centres res;pectively* advanced differentiates predominate. Tue trachybasalts are of the cnrsfr oifratidcneti e.Ms ye.hwvr 'nrc -.ariety, similar to those of Mawenzi (q.v.) but with plienocrysts of panralel swarm, trending W Wiird . whcetich inesect.Mst tykes,two entre T:

,oLutcr dimnensions. prle wr,tedn N .EE,wihitrct tetv ete.Tisout11hern part of the Shira Plateau rises the conical hill called Platzkegel. ntsonalteedksadaeol ceaial ersrtd

.zcd remnant of a nmajor vent-infilling occupies a roughly central position '-kiho.-The central and largest of the Kilimanjaro centres is a"p-tto the Sliira structure. The vent-infilling is mainly composed of basaltic volcano thec dome of which has been obliquely truncated by collapsc resuilti2,with some basic lavas, and is penetrated by intruIsions of doleriticanI formation of a caldera n. ntahl ie ndaee.Tehgetpr

lr.Similar small intruisions occur at the eastern limit of the south ridge caldcra rim is on the south and culminates in Uhuru Peak (formerly Kaises iOn ilic inner slope of the main Shiira Ridge a small subsidiary centre of Spitze). 19,340 feet high. From the floor of ithe caldera rises an Inner (effuNicon became active at a late stage. A radial swvarm of (tykes, crater 000 yar(1s in diameter. Within the Inner Crater lies the Ash Cone cii::!,, s.rmdar to the tava%, is conspicuously exposed on the ridges, and terme(l the "Ash Pit", the latter 370 yards in dliameter and 425 feet deepconccntric sheets of intrusive rocks, concordant with the lavas, are visible Cratler is the site of thie last activity of tlie mountain. The southern shijol I:arc dissected by glaciated vles but oneyrar thie Great Wet Nisoutlisset Side doeis erosioni expose any considerahle section into thec %itri--tst of the Shiira Plateau, in ithe upper parts of thec Kikafu Valley, th ocn.Hre taotli00fe,te(isetO sdeet ii h dl.itre" Sediments are exposed. Tlhese alluvial deposits contain a wide variety rocksnarc torbe ftaoun.Th more0 reent, ilc a havcio tendedps tod flis (oldi,incluiding ijolitic rocks not seen elsewhiere on the mountain. T'hey post-date ok and catoflaeksoand.in Thirego nothingeofnth oldvaer strcture( is seen dvi

ivsity of Shira.an csfltkaninlisrgonoligo h iirsutreien2

taaso Kb so srngakaie ifee: inan anefrmAbove ...e upper rectangle porphyry group is developed a spect. l

-*ndesite, through trachyte to nepheline-rich phonolite. A wide range of these prhr ucsinmr hn300fe hc opiigterobpecs occurs, and a detailed succession is well-established, especially in the the smnall-rhomb porphyry group and the Caldera Rim group. The n

~s.Near the centre dips approach tfice horizontal on the flanks they steepen popyyIa.be,sdesntal safil emt esrb aai

Ps. The lava flows of Kibo flooded westwards almost completely over Shira - -composition- from trachytes to phonolites with mega-phenocrysts of ali pat

"me cast they were strongly deflected to north and -south by the peak of Mawenzi. showing rhombic cross-sections; some varieties are very close to the type !h

tcetions are available only on the south and west slopes and nmoraines and - Oslo region, whilst others can be compared with those of Mount Kenya a1 in

.ae~iial deposits conceal the lavas over considerable tracts. The maximum Erebus in -Antarctica. There is .considerable variation in phenocryst siz il t !nr;I thcknes o thesevral avagrous, ach f wich ay omprse core offrequency and also in the presence or absence of nepheline mega-phenocrvy n

%-al flows, isg~iven in the following account. myc prs oof these features have proved stratigraphically significant.

li,' sicesson fJvashasben dterind a folos: IThe rhomb porphyry grouip (2,000 feet). The lavas of this u,isccsino aahabendtrieasflos--characterized by abundant phenocrysts of alkali feldspar up to one and f. :es

l nner Crater group in length, sometimes comprising as much as half the volume of the tie

Caldera Rim group - matrix is usually dark grey and aphanitic to glassy, but locally it may i AV C

SmLen hobpophr group- There are no neipheline nmega-phenocrysts. It. must have been the .1~

Rhom-pLent r group .distributed of all Kibo lavas since flows of this type pass off the sheet booir he

Uprhomb agl porphyry group- north, north-west, and probably south of the mountain. Individual flov.-s. A)

Upper tractyanglesporhyr group exceed 50 feet in thickness, are known to extend more than 25 miles from ti r I ti1

Lower rectangle porphyry grotup ' point of origin. They moved by characteristic tunnel-flow mechanis,m.Lava Tower trtchyte group ynot divided on map. Locally in the region of the snouts of the Penck and Crednter glacier I1

Lower trachyandesite group I porphyry is underlain by the distinctive Penck rhomb. porphyry (400 feeit I-1 il, I

ta number of localities (and at certain well-defined stratigraphical horizons), very sparse feldspar phenocrysts in a very basic matrix. Elsewhere :,o

fluvio-glacial and alluvial deposits occur among the lavas of Kibo and in porphyry succession commences with the WVeru Weru agglomerate whicr S :et

-ey may reach thickness of over 200 feet, e.g. in the Karanga Valley but their thick in the Weru Weru Valley at 4,200 feet altitude. Neither of these t. ii; - as

are to small to be shown. extensive outcrops and they have been included in the rhomb porphiyry -. i

A; of the Kibo lavas seen belong to the earlier part of the Pleistocene but the mp The Lent group (1,000 feet). In many parts of Kibo the lavas n-i . lb

i.mmb porphyry group and Calder-a Rim group erupted in the latter half of the porphyry group were succeeded, after a lengthy erosion interval, in; i

ne and the Inner Crater activity is Recent. trachyandesites. trachytes and phonolites. These form extensive flows on rn

lower trachyandesite group (200+ feet) is the oldest set of lavas exposed. It and southern flanks of the mountain, and appear to have originsted as flam v In

I.tricted outcrop near the Lava Tower and in the Umbwe Valley at 13,500 feet from fissures and centres. The most prominent centre, the Lent Peak n, m. ,I

Pfeet. Lithologically the lavas resemble the upper trachyandesites. Kibo, is an impressive collapsed dome.

Lav Th-r tacyt grup(30 eet i sen nl i afewplce hih n heThe simall rhaomb porphtyry groiup (700 feet). In the central regivii it)

LaTwe rhyerop(0fetisseonyiafeplcshgonteporphyry group is succeeded by a group of lavas later in age than the Lent .An

* c\t flanks of Kibo. Lithologically the lavas are green, fluidal, fissile and are are characterized by abundant, euhedral rhomb-sliaped phenocrysts of rek: vI 1

-. 'sPicuously xenolithic. Petrographically the lavas are aegirine-rich trachytes. size, generally less than half an inch in length. Sparse, small rnega-phs '

t ovver rectangle porphyry group (2.000 feet) is also exposed in limitedI areas neplieline are also commionly present.,uth-ivest flanks. Petrographically the lavas are trachyandesites, differing from Anakcinie sycnu'te 01,000+ feet). Within the central portion of Kiho. tI

-and lower trachyandesites in the nature of the plagioclase mcga-plhenocrvs'ss. the Great West Notch show that the rhomb porphvry grouip is sucL

lower rectangle porphyries the mega-phenocrysts are of andesine vithi a conisiderable thickness of analcime-sycnite, thie bottom of which has not becr

aTcross-section showving a legth/thickness ratio in the range Ill to 4/I in syenite contains small rhombic plienocrysts of alkali feldspar, andi in otl A~ II

traclhyandesites the feldspar is a labradorite with a more reguliar cross-section resembles closely small rhomb porphyry. It is, in fact, thought to he a pu,lengii/ticknssraioinherageSI to 5/1.s(nial rhomb porphyry magmia which was extrudled under presumicd tnilengh/iicknss atioin he rnge5/I o I/I.cauldron subsidence proceeded. and cooled slowly by virtue of its large

inse of their restricted outcrops in the same area these earliest tliree groups of io'Isr.Abudrepitceralrgaeaftmelins

Ahave been represented as one unit on this map. Mo%hi at lheighits of below 3,000 feet. In places it shows tlhe mounded

upper/ trachlyande.sit- grou4p (200 feet) antd the upp,-r rectangIk porphyry *iroIIJp chmaracteristic of "lattar'. This deposit was formedi by enormous debris flu's

tl). Trhese two groups are similar in petrography to the loweer grOupsl- Of the development of thie Kibo Barranco which took pl-ice at some period sub-v I

.:,)e, buit have a much wider distribution, again mainly in thec west and south formantion of the small-rhomb porphyry group and before thec otitpotirinve

Lavas on the nortlhern slopes of the mountain approaching the Anmhoseli Crater lavas.probably to be correalaed with the upper trachynndesite group. as are thiose Tlhe Caldera Rimp grouip (630 feet) is a grouip of rhomb porphryrics 551 I

*eXPOSuire west of the Karanga River at the southern base of the miountain, large, well-formei niega-phenocrysts of alkali feld%par accompanied I'-.

rrectangle porphyries extend westwvard on to the Shiira Plateau and are also abundant mega-phienocrysts of nepheline %hich may approachi one inichi'

utteY sections in the 3,000 to 4,000 feet level east of Macharne and at thie These lavas formedI a series of flat-lying flows filling a caldfera uAhich f m:

.t u and Kikafu rivers. small rhionb porphyry lavas. 1.ater they spilled over the sidecs formiing '

upper trachyandesite group is separated from thec underlying lower rectangle channel flows on the flanks of Kibo, especially on the north and north

*groupl by an important erosion surface, btut it appears to gradle upward into wvhcre sonic extend to the edge of the map. The present summit ridlge '

Irectangle porphyry groupthog lava-flowsshwn transitionalpleors memhcrs of this group. Nepheline rhiomb porphyries were also erupted Jr !

separation of the two through ss h osfreote vrinrry ph cytparasitic centre on the Saddle.

4

!nner Crater group (425+ feet) comprises nepheli: ch aegirine-phonolite Shira at,. Laguimishera zones. From the west to the north of Shiri aIsmall rnega-phenocrysts of well-shaped nepheline and more irregular ones ofwihmrtan10cesgnrlymoedpredhninheR boe

ina. hs age. thei lowt croneuils the preasento cavder which formped atd ar widest range of petrogmaphic types known in the parasitic activity is fout i,.,.-.ce i age -Teirlowconefils te pesen cader whch frme attheboth pre-rhomb porphyry and post-rhomb porphyry activity is known. ~

Caldera Rim group. They spill over the rim of the caldora and form - Shira zone forms a well-defined anid narrow maised linear zone extending fret . h* log, arro flws n th noth-est,andare lsopresnt n te wet ad -Shira Plateau to the plains near Sinya. The lavas are chiefly andesites an .

The groups of cones lying to the south and north of this zone have been :. .

'lions.. A number of dykes are present on the slopes of Kibo above 13000 ease of description, to an Engare Nairobi zone and a Lagumishera zone ci '. Y.)ly on the south-west and west, but a few are recorded high on the north. Presenit Volcanicity.lResidual volcanicity is now confined to Kibo, -c :I is* idial, from 1-8 feet wide. They comprise trachybasalts, rectangle porphyries, expressed by fumarolic activity associated with the Inner Crater ring frak *, ile

rphyries and phonolites. fumaroles are believed to indicate waning activity, but they may represeni lo: -it

* d C s-Associated with the Kilimanjaro volcanicity are small but staerinth volcaniciWety. hr h iimnaolvspssudrte,dventitious cones. Two hundred and sixty-three of these ntinor volcanic grerat "Iaharfieldextenofn wshiara stMrubyn the iimnmroiaasp ss ode the a. Ji.been mapped on this sheet; generally they are situated on the lower - retlahar" wa firreld irextendingmestad tobrybyn the colpeo h atwlmt of the cra . i s

*ending-in zones down to the plains, but they also occur on the Saddle -"lhr a omdi eettmsb h olpeo h atwl fteca .lOi:,n 14,000 feet. The cones are usually-only a few hundred feet in diameter - In gene(al, north of the Arusha-Moshi road the Meru "lahar" formn,aithe same in height, but several reach a mile in diameter and over five topography whilst south of the road outwash from the lahar forms a more' ri - n.tcet in height. -They consist mainly of scoria aiid ash, but several have The "lahar"~ deposit consists of boulder beds, over 80 feet of which are v .. , elava flows forming extensive fields as in the Upper Rombo and North Sanya River sections. Al] the boulders are of types lava common on Meru.

a. Rock-types identified are: ankaramite--oceanite--olivine basalt- Alluviu,ni.-Most of the valleys of Kilimanjaro have alluvial terraces ir' r r.te-phonolite-basalt-andesite--trachyte. However, these cones have not parts wvith boulder beds conspicuous among the deposits. These terraces -' n

udied in detail and there may be an even wider petrographic range. At least the plains north and south of the mountain to form wide spreads o'f 2-.peiriods of parasitic eruption are known. The later post-dates the Caldera gravelly deposits. The Pangani deposits in the south consist mainly of I C

and hence is the youngest activity on the mountain except for the Inner Kikuletwa and Sanya rivers have narrower alluvial plains, and stroI - fs . The older pre-dates the rhomb porphyry group but may post-date the lacustrine and alluvial deposits have formed west of Shira where the drai e

.!.aiigle porphyry group. In addition much older centres have been identified Sanya River was temporarily blocked by the Meru "labar"'. Extensive allus: .

lavas of Mawenzi, and other periods of parasitic activity certainly occur. gravel deposits surround the lacustrine deposits of Amboseli.ire mostly arranged in well-defined belts corresponding in some cases clearly Amiboseli lake beds.-The lacustrine beds in the Lake Amboseli

* I; regional tectonic or volcano-tectonic lines. considered to be Neogene in age. The lowest strata are the Si,iya Beds ss

a',ddle zone. This zone comprises eleven eruptive centres arranged in two of dolomitic limestones with some sepiolitic mudstones towards theirWNW-SE inesbeteen he ain entes o Kio an MaeziTheitmestones are the main host-rocks for meerschaum, which is found

WNW.iS,Einlpart pre-Cawerath Rmagopin agntes and Kinclunde MawnkaaiThes sporadic bodies. The Sinya Beds are overlain unconformably by the Ain;

*traclhyandesites. The southern line entirely post-dates the Caldera RimThsargen,epoicclywthmkdttxtricndwlinpincludes ankaramites and basalts. An isolated centre betsveen the lines 01 Tuikai Beds which lie unconformably on thesc clays in this part of t cb tasalt and nepheline rhomb porphyry. constituted mainly of impure limestones with lesser marls and clays.

I'anntbo zone. Ti zoneaper to cotnethe otenSdl ie toth Calcareous ituflaceouis grit.-Deposits of wvell-bedded Calcareous sat,

of Mawenzi. Comprising more than a hundred cones it is the densestom selagyofavfrmntatinahckssfoer5,irasitic cones on the mountain, The upper part consists of lava and scoria south-west of Lake Chala.J2y ankaramitic in nature. Thei part within and below the forest, consists Red soils.-South of Kirua are extensive alluvial deposits of saw

*.sh cones with ankaramitic and olivine basaltic affinities. All this activity conglomerate with secondary limestones, all distinctly red in colour. Sir:* g.Lake Chala lies isolated at the south-eastern extremity of the RombohaeawdsrdbuirglrocrenentelwesopsfKii

,iccupies a large caldera, some 300 feet deep, and is surrounded by *a of Slhira and east of Mawenzi but are not shown on this map. In placc!Wof agglomerate and tuff. The walls expose Mawenzi-derived lavas. It thicknesses of 200 feet. Outcrops of Precambrian rocks are all surrirunde,(tiat the large spread of water-deposited calcareous tutTaceous grits in this of duricrust which may be highly calcarcous in places. Surface hlme'ione I

rner of the sheet wsas derived from the Clhala centre. some of the parasitic cones in the Shira Zone and locally elsewhere.zoc,Ths on i acnsicou ris(iaraemnain foma oitWind-blown sands.-Along the western edlge of Lake Amboseli there ai, it

* zoe. hiszon isa cnspcuos rasedare emnatng roma pintdeposits of wind-blown material. The lake floor itself consists of flIne niL2Saddle at 9.000 feet and running in thec general direction of the Pare places, contains crystals of gaylussite, becoming miore plentiftul as one tII.

Somec twenty dissectedI basaltic scoriaccous cones overlie andi partlyeatrdinoKy.''ick older series of basaltic to ultramnaric lavas whtich apparently form theeatrdinoK y.

raiscd area. These older rocks appear to be overtain by lavas of the Although slhown on early topographical nmaps as s.aline, I. ake Ant1o-kup on (heir eastern margin, and may prove to correlate with thie Neuimann particularly rich in either salt or soda.

I.or to hc even oldcr. In the absence of poritive evidencc, the wh)oIe if RrrGI0NAL STP,UCTtIRA!. FEATU.RISbeen miapped as parasitic lavas, which do, in fact form nmuch) of ilte

,sure. The stratigraphic position and petrographic claraicter aire citisely The Kilimanjaro massif appears to he SitUated at tlhe inter%ection ir*oseof tte01 Mloggrop (qv.)norh ofSttra.tectonic lines: the NNW.-SSE. faulted Pangani TroLugh, situated hetomc

iof zone. B Mlog ruv (.. northanf areaaMountains and the Lelatema Mountains and an E.-W. trendling -lone .

ine f eyod et te otte lns fStrai nextending from the Gregory Rift Valley 80 miles or so to the wcst. \ine fvr lland eroded cones occur, but their relationship to tlte faulting pre.dates the volcanic aclivity and wvittiin ttte hounds of it,.

-unknown.

6 structures are buiried.7

VOLCANO-TECToNIC FEATURES- The wate, - Lake Chala has accumulated as a result of seepage of gcVoLco-TcroNc FxruRs -into the large expiosi?on crater whaich extendsbelo°' th water table

. gnment of calderas, volcanic vents, parasitic cones, and dyke swarms is G Atabr m the map and these lines clearly have some form of structural control, BIBLIOGR

-tber this is of purely volcanic origin or has regional significance is not DOWNIE, C. 1964. Glaciations of Mount Kilimanjaro, north-east TBull. geol. Soc. Amer. Vol. 75, No. 1, pp. 1-16.

ECONOMIC GEOLOGY D. W. HumpH_IEs, W. H. WILCOC_soN and P. WILKINSON. IC

haum is mined at Sinya, north-west of Kilimanjaro. The deposits are of Kilimanjaro. Narure. Vol. 178. pp:828-830.n.custrine limestones, associated with green sepiolitic clays, which extend across HUMPHRIEs, D. W. 1959. Preliminary notes on the glaciology of K

into Kenya along the south-eastern margin of Lake Amboseli. Meerschaum lour. Glciology. Vol. 3, pp. 475-478.. m pipes at a modern, well-equipped factory inArusha. Larger pieces are used Geology, volcanology and glaciology of Kl.

nieerschaum pipes, smaller pieces for inserts in pipe bowlis and the fine Guidso-boDk No Moun Key n-Kl,ajro h onanCuir constituted into blocks (called "arcon" to distinguish it froma natural Gude-book to Mouna renya and-Kiattrnar The Mountain Club

.;schaum) -from which pipes, with the excellent smoking characteristics of - .N .K.i rschaum, are made. -W-LCOCYsoN, W. H. 1956. Prelimiary notes on the geology of

.w;r is forrning round the mouths 6f fumaroles in the Inner Crater of Kibo, eol. Mag. Vol. XCIII. No. 3, pp. 218-228.,_conomic amounts.

cs for building and road construction are in fairly plentiful supply but theretage of suitable sand for building purposes near Moshi and in the areasl-v volcanic rocks. Building sand is quarried in the Pangani alluvium neari Chini.r .Supply. Kilimanjaro is situated in the centre of an extensive arid area of

,C;t where the plains normally receive less than 20 inches of rain per annum.i, a increases on the mountain itself. The north and east sides of the mountain. short rains (November-early December) while the long rains (April-May):1. on the south side. The highest rainfall (over 60 inches per annum)

:lhe southern slopes of the mountain centred on Machame and Marangu.ih and north-east side of the mountain, rainfall is lower, usually between 30

clies.:.nent surface water is found mainly on the southern slopes of the mountain

lie larger streams flow perennially. With the exception of the Karangalo and the Rau, all these usually dry up before reaching the plains in the dry

I:l the north and east sides of the mnountain, permanent surface water is(he forest belt on the lower slopes and only the Lumwe stream flows below

line in the dry season. On the upper mountain slopes, surface water isniols only at a few places (e.g. near Peters Hut) in the dry season.u h much of the rain falling on the mountain is dissipated in surface run-off.,.: is readily absorbed by the pervious volcanic formations and tends to

,ihe botton of the volcanic pile, held up in some places by impervious lavav.crge as small springs which occur frequently in the forest belt. Most of

.; > are utilised to feed pipe lines which serve the population on the lower,.' mountain.-prings occur at the foot of the mountain near Moshi and at Miwaleni on.lc. On the south-east, east and north sides of the mountain, all the large

. tovu, Taveta, Ziwani and Loitokitok) are located in Kenya.

\ty borcholes have been drilled for water in the Kilimanjaro-Moshi area.horeliolcs drilled in volcanic formations around the foot of Kilimanjarouccessful. Large quantities of ground water can be reached within 400s surfacc. Boreholes drilled near Moshi and Sanya Juu have frequentlyof over 2.000 gallons per hour; some have given much higher yields. In!njaro (Engare Nairobi) area, boreholes have been less successful. On the

k limanjaro several successful boreholes have been drilled on the southern,r!lcular near Marangu. Uru and Machame where surface water is abundant,d ground water horizons are struck at relatively shallow depth. Many

.itesl5 have proved dry or ground water from levels near thc surface hasiih continued drilling in attempts to increase water yield. On the eastern

K. ilimanjaro, only one borehole, at Keni, has been successful; five other,1 !led in NMkuu and Mashati areas were dry. 9

r 1. - . .- i n | 3 X 5g.. , , E jst 6 t i'

slowls Wm AOlStl1XM1031MGOILYMIJSS11123X111101 MIS eo ON1s SS Z101 O t'S

>3S INS 't 0 1^]1 ulm *a ssM SS n tit 3MX ]Na

-< t .. *c .. -ed't 1 .i fBO! 0 s e ! fl

, A WM 3 S O SJ W Sil

Sm owru aU"N iiiisn

,4 1Y 1) 1^Dwx n

.. . . -Ca.' -I

SlOIASThi 4

1sl11i0MOLi1s1311mU IiSN *lLd%10 IA

,9 j 3t3W: Y 0 JA IS 01O *S M38 WS ll W sw=4

-I 3 01 W l 'O N S f O IN t l- U SO S d *I J N ' IIte NI I h M3 3^315 C 8C 'ON Ms s5 d JiArl 10 s o1 S dIiSo $ U IN IlNJ tljU ',

50

Tal 40

313

P20

10

4 ------

00 10 20 30 40 50 C 70 I0 90 100

Si KIM LIWt

Table 4 DetailFor classification of fine-grained soils and fine fraction of course-grained soils.Atterberg limits plotting in hatched area are borderline classifications requiring use of dualsymbols.Equation of A-line:

PI = 0.73 (LL-20)

Notes:The above charts reprinted with permission from the Annual Book of ASTM Standardscopyright the American Society for testing and Materials, Philadelphia, Pennsylvania.

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