Afri<:an Study Monographs, Supplementary Issue 2: 45-56, March I 984

FOSSILIFEROUS LOCALITIES OF THE NACHOLA-SAMBURU HILLS AREA, NORTHERN KENYA

Martin PICKFORD

National Museums of Kenya Hidemi ISHIDA

Yoshihiko NAKANO

Faculty ofHuman Sciences, Osaka UniJiersity Hideo NAKAYA

Faculty of Science, Kyoto Unil'ersity

ABSTRACT In the four geographic/stratigraphic areas of the Samburu Hills and Nachola. west

of Baragoi, Kenya. a significant number of fossiliferous localities was found. Nachola area is dated

to the middle Miocene, the Namurungule Formation in Samburu Hills to the upper l'vliocenc,

Kongia area to the Mio-Piiocene and Holocene to the area near Suguta Valley and in the drainage

systems of the Samburu Hills to the Holocene. The site BG X in Nachola yielded a number of

fossils provisionally assigned to Kenyapitlzecus. An important large hominoid specimen occurred in

Site SH ~~ of the Namurungule Fonnation. Undoubtedly a great many additional sites await

discovery.

INTRODUCTION

Fossils were known to occur in a few places bet ween Baragoi and the Suguta Valley many years

ago, but little systematic study was undertaken until 1980. Previous to this, fossil wood was

collected at Emuruilem (Site BG W) by amateurs (Baker. 1963 ). In !980, the Japan-Kenya Expedition, under direction of one of the authors (H.!.), started

prospecting west of Baragoi and located a number of fossiliferous areas near Nachola (Ishida eta/.,

1981 ). During 198~ an extended Held season was spent in the region and a significant number of

important sites was found ranging in age from middl~ Miocene to llolocene.

This report is to place on record basic informaiion concerning localities discovered during the

1982 field season. The basic data includes the position of each site plotted on aerial photographs;

the stratigraphic position of each site, and details of taxa collected therefrom, together \Vith the

total number of fossils found in each site.

Fossils recovered during 1982 occur in four basic geographic/stratigraphic areas. Middle tvliocene

fossils occur in sedimentary intercalations in a volcanic sequence in the Nachola area 10-15 krn

west of Baragoi (Figs. 1-3). Upper Miocene fossils occur in the Namurungule Formation Samburu

Hills 27-32 km west of Baragoi (Figs. I, 4-6). Mio·Pliocene fossils occur in the Kongia area a few

kilometres north of the Namurungule Formation, while Holocene fossils are found in grey silts near

the Suguta Valley and in travertine and terrace deposits in the drainage systems of the Samburu

Hills (Figs. 8, 9). Undoubtedly a great many additional sites await discovery.

J5

( 1' -._I I I h I~ I IF I /I I I ~I 1-'f.~l I I I I r' n ~ /l I I ( I) ~r-1 IJ \ J rl I \ I I,_ __ lf I 1---1' Ill ..__/ r L :=::::t ) \ •• :::7'-'1', -!d ( \j I~ ,L 1 r / V11m: f{ I I 1- k ( I '( 1 I ~(I ~~ I J-4 I I ( I ~ II I !,__/ I I I

/~I 1 I I 1 I I NACHOLA fl I~ I I ( f I~J·u \ I II' ~I F1 J 111 ~{ I I r';-/ 1'--\ I 'Y'I"'~J{ I ~\, I I I I I"Y I l?l I I jl I I UI"KI 'rr ~I l"'ll~~ I~ " ,/ ~

I ,---1 1 11~1 I .~ <--:':- I \--) I r.-- I I ..-I , I I I ~~1aj_l_ 1\1~' I I I I 1/ KONG lA r- AVENA ATURKON ~·

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1\~ I"!"\ 1~1 I.J t I 1-- .. ( I I II I Nl I \ I fiH \{'(1\ ~ )i )~ardg;;;-. r . )1 I I I I I \ v (\JJ---T' I I r,.J I I I ll I\ J \ ,---YI I~ I~'"] \._. l'lP lA-\

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--,_1 NAMURUNGULE I~ II kf~-n (,Y' I? I "-- 11 /h.J/1; t-/ \1 ~-'· N ·~I !I) 1 }---- r--:s ~ -1 ~~ I u 1 (--. I r A)\..L.___ ,_~ , x I'· 1 I \ /

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~ I I h ~ i ~ \,\ I I ,(" +=" ( I lr~~"'. h I I T"·J ! I l/ I l)\ I I~ II I I I ~NAKAPORATELAOO

I I 1,1 I ~-. I I ;!, II 1'11 I "I 1'~1 'I I (I\ : l\_1 I I I I I\ I I ;1 1"',1 [

~ ~

n :r, ., 0 ::0

0 _tl

:r: Cii =

I tl ( I / l'lJ I I I ;I~ I~ I~Y~ I I) I JJ I k! _Jf11t-h· I I .-! II . I) I r (f I I I" 1~1 1i ~ h~ I lr+-'~ ~ /1\ I"'\ I I 'I

0 ?"' :<

/"'~ I I I ~ I( I !I W---'- I .I If\. I I I y I I\ I l I \--_ JO 50 40 0 1 2 3 4 5

z ~ :r, ~

Km z 0 ., ;:I 0.

:r: z ~ :r,

Fig. I. Location Map: Baragoi-Samburu Hills ~ -< >

Fossiliferous localities J7

The Nacho/a Area (Fig. 2)

Fossil sites have already been reported in this area (Ishida eta! .. 1982; Baker, 1963 ). Mammals

tend to be rare in the sediments of the Nachola area, but crocodile and turtle remains are abundant

at some sites. Fossil wood is also common at certain levels in the Emuruilem ,\!ember. The most

'. -. ;,.~-·~.;, ..

. .... . ..:;~. . . .~-" ~{i" ~

~ ~ . ' j"-;(;"'

"+ ·-4 .)

Fig. 2. Nachola Sheet

J8 M. PICKFORD, II. ISHIDA, Y. NAKANO and H. NAKA YA

important site found in this area during 198~. was the Site BG X, which yielded a number of

fossils provisionally assigned to Kenyapithecus, plus a few other mammals. Figure 3 summarises

the collections from the Nachola Sites. It should be noted that fossils occur in sediments at various

levels in the succession. The lowermost deposits occur below the volcanic sequence at the eastern

edge of the volcanic field. Above this is a series of phonolitic and basaltic lavas with intercalated

tuffs and sediments which yield abundant fossil wood and rarer mammals. The upper part of the

Nachola sequence is comprised of a thick sequence of basaltic lavas.

TAXON

SITE

u v w X

ClJ c

~ VI ~E~ "0 ::J • ~ "0 'iii u ClJ ::J ·-

c ::J ~ ClJ .J: ·~ 0 ClJ ~ ..... :.= "0 - a.- ClJ '- c "0 c-

•n :;:::; X "' ·a.- C 0 .J: ClJ "0 •- C C VI ...... >- .., .J: ..... u ·- - E ClJO E c- o.oo- ::J c u u c 0 VI >- 0 E c c - 0' .E E VI 0 .~ - ClJ c E ·- ·- 0 0 0 ·- '- '- ClJ > ClJ 0 ClJ .J: .~ '- ::J a..ut-a..~::s::::tf)<!>Oa::<!>t-O::~

• •

• •

•

•••••••••••• • •

Fig. 3. Distribution of fauna- Nachola

The Sam bum Hills Area (Figs. 4 and 5)

VI

VI VI 0 --0

>---c 0 ::J

0

75 38 3

73

The uppermost Member of the Aka Aiteputh Formation, comprises palaeosols. weathered

basalts and siliceous limestones, and minor fluvial sediment lenses. It is generally poorly fossilerous

but has yielded molluscs and mammals (Figs. 4, 5 and 6). Baker ( 1963) provides a brief description of the Namurugule strata, which he included in his

Tirr Tirr Series. The strata arc, however. stratigraphically well below the Tirr Tirr Formation which

has been dated at 3.8 m.y. (Baker eta!., 1971 ). Uncomforably below the flat lying Tirr Tirr Alkali

Rhyolite occurs a westward dipping sequence of Nagubarat and Kongia Basalts with intercalated

sediments. best exposed in the Kongia area (Fig. 8). Unconformably below these lavas occurs the

Namumngulc Formation which is Upper Miocene in age. A large number of sites is now known in

Fossiliferous localities JQ

Fig. 4. Namurungule Sheet

the Namurungule Formation (Figs. 4 - 6). but most of them yield rather scrappy fragments of bone and teeth. Aquatic faunal elements arc frequently found, but terrestrial fossils occur in many of the sites. Probably the most interesting and important site found in 1982 is Site SH 22 which

yielded an important hominoid specimen plus a moderately diverse vertebrate fauna. Hipparion and bovids occur at many sites while giraffids are rarer. Deinotherium and Tetralophodon are

moderately well represented in the collections. while most other mammalian taxa are rare. Fossil fish. turtles and crocodiles are ubiquitous. Gastropods are. however. notable by their absense.

50 M. PICKFORD. H. IS III DA, Y. NAKANO and H. NA.KA YA

Fig. 5. Nakaporatelado Sheet

Two intriguing sites yielding impressions of leaves. feathers and foot prints were found (Fig. I 0).

The well-bedded facies common over much of the Namurungule area may well contain many more such sites.

Fossiliferous localities

TAXON

LOCALITY

1 4 5 6* 7 8 9

10 11 12 13 14 15 16 17• 18 19 20 21 22 23 24 25 26 27 28 29 30 31. 32 33 34 35 36 37 38 39 40 41 42 43 44 45. 46. 49

111 011 111 c -.c 111111 c

41 ~Eg .g~ 2::J

c -o c c -o ::J -o ·- ·.:: ., E '0 c ·u; '0 .. .. 0 ·- 0 c 0 ell 0 c ell ell o -::J-c 'O~~~~~~c~-co ~ :::-o~-oo .-oell~ 0111 -ouO-o'Oe~~ 0 Ill '0 .. u ·- ell 0 ~ :5 0 > u 0 ·;:: c ~ ·- :.:: 0 ~ ell 0 E >- c '0 .!: ~ 0 0 ·- 0 .~ c N c ::: ::J '0 - u u o c o ·- "' E u c ~ !: c- ~ c >- c 01·-1/l Ill 0 - 0 ~ ~ ell >- ·- - ·- c ~ 0 c ~ c > c ·- ~ ell ·.:: c ~ > 0 ~ ell 111 0 ~ ~ ·- >- 111 ·- ~ 0 ~~U~~>O<IOO~U~UIZ~~~m

•

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• • • • • • •

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• • • • • • • • • •

• • • • • •••• • • • • • • • • •••• • • • • •••• • • • • • • • • • • • • • • • • • • • • •••• • • •

• • • • ••••

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• • • • • ••••

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• • • • • • • • • • • • • •

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•

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0111 >-'iii - Ill• :=o CIJ.. 0 ::J

0

38 161 43 10 29

142 67 2

51 107 30 46 22 24 26 6 1

38 32

166 24 22 28 28 67 19 1

37 9

11 4

42 1

26 18 13 1 1 4 1 5

16 1 2 1

Fig. 6. Distribution of Fauna- Namurungulc (*Aka Aiteputh Formation)

51

52

1- CARNIVORE 2 -RUMINANT J- RHINOCEROTIDAE 4-UNKNOWN 5-BIRD

M. PICKFORD, H. ISHIDA, Y. NAKANO and H. NAKAYA

Bedding plane with footprints

01

0

Metre

Fig. 7. Footprints at Site 32

Fossiliferous localities 53

Fig. 8. Kongia Sheet

111e Kongia Area (Fig. 8)

Six to seven kilometres north of the 1\amurungule Formation is a thick succession of basaltic

lavas. In a few places thin sedimentary intercalations are known to occur between lava tlows

(Fig. 8). A very preliminary survey made in 1982 indicated the palaeontological potential of this

sequence, which unconformably overlies the Namurungule Formation. Two richly fossiliferous

5J l\L PICKFORD. H. ISHIDA. Y. NAKANO and H. NAKAYA

Fig. 9. Ayena Aturkon Sheet

sites were found, both of which yielded abundant Mollusca, but few vertebrates. However. one of

the sites (SH 47) yielded 1/ippopotamus. fish and a varanid. The hippo is particularly interesting as

it is the earliest local record of this group. The older Namurungule sites, although clearly aquatic in

their depositional environments. have not yet yielded Hippopotamus. This finding is in accord

with currently available infonnation concerning hippopotamid origins and distribution (Pickford.

1983) which suggests that the earliest known Hippopotamus occurrences in Kenya are about 7

f.'ossilifcrous localities 55

million years old. Prior to this time, hippopotamids were represented by Kenyaporamus, the genus

which occurs at Namurungule. A separate report on the Kongia Mollusca has been prepared (Pickford, 1984 ).

l

D

D

D D

Grey silts, travertine --~-- Sites GB 1-10

Ti rr Tirr Fmn

Nagubarat Fmn

Kongia Fmn~.-- ~-- .. ------i----SH 47-48

.!! ~- 10-16, 18.19, Shale\ brown conglomerate-S,---~ --4, 5. · .25.29, 32,33,35-38,

2 e 28. 39. "'41. 42. Mudf low :I u.

E SH 1, 7-9,20-24,28,27,30, Shale------------·----~- i--- 34,40.43,44.49,

limestone- - - -

Basalt

.J: ... :I Q. I) c: ... E < u.

· SH6. 17, 31, 45, 48,

Fig. 10. Stratigraphic Positions of fossil sites: Sam":JUru Hills

Holocene Sites Holocene sediments occur in the Suguta Valley as well as in the present day drainage feeding

into the valley. High level terrace deposits occur extensively in the Samburu Hills. These presuma­

bly accumulated during a period when the Suguta Valley was filled with water. The resemblance of

the grey silt facies to the Galana Boi Foml<llion, which occurs further north in the East Turkana

area, is marked.

5o M. PICKFORD. H. ISHWA, Y. NAKANO and H. NAKA YA

In some areas higher than the highest lake terraces, occur river terraces and travertine deposits. The latter frequently contain fossil leaves and molluscs. A separate report (Pickford, 1984) dis­cusses the distribution of Molluscs in the Holocene sediments.

In the vicinity of Baragoi Township is a series of fluviatile deposits which contains subfossil snails and vertebrates (Site G B I I).

The value of the Holocene deposits lies in the information they impart about conditions in the Samburu area in the recent past. The Baragoi site contains molluscs usually found in conditions much colder than those prevailing at Baragoi today. The Suguta Valley, when full of water would undoubtedly have had a marked effect on the local climate. The travertine deposits indicate the former existence of lime charged water seepages in an area which is now virtually waterless.

ACKNOWLEDGEMENTS We acknowledge the help of the following organizations and indivi­duals:

The Japanese Ministry of Education, Science and Culture, The Kenyan National Council of Science and Technology. The Office of the President of the Kenya Government. Administrators of the Samburu District, Mr. Richard E. F. Leakey, Director Chief Executive of the National Museums of Kenya.

REFERENCES

Baker, B.H .. I 963. Geology of the Baragoi Area. Rept. Ceo/. Sun·. Kenya 53: 1-74. Baker, B.H., L. Williams, J. Miller and F. Fitch, 1971. Sequence and Geochronology of the Kenya

Rift Volcanics. Tectunophysics II: 191-215. Ishida. II., S. Ishida, M. Torii, T. l'vlatsuda, Y. Kawamura and K. Koizumi, 1982. Report of Field

Survey in Kirimun, Kenya. 1980. Study of the Tertiary Hominoids and their PalaeoenPiron­melllS in East Africa l: 1-181, Osaka Univ. Osaka, Japan.

Pickford, M .. 1983. On the origins of J-lippopotamidae together with descriptions of two new species, a new genus and a new subfamity from the Miocene of Kenya. Geobios, 16: 193-2 l 7.

Pickford M., 1984. Fossil Mollusca from the Samburu Hills. Northern Kenya. African Study i\/ono­graphs. Supplementary Issue No.2: 141-145.