This post is a contribution by Dr Edward Pollard who was with me on a recent trip to Tanzania as part of a British Council sponsored research grant with the University of Dar es Salaam
Prehistoric animal tracks, Swahili ruins
and Climate change in Tanzania
Tanzania has several World Heritage Sites
including Ngorongoro Conservation Area, and the rock art at Kondoa, both in the
Rift Valley, and the Swahili sites of Zanzibar Stone Town, and Ruins of Kilwa
Kisiwani on the Indian Ocean coast. I returned last week from two weeks of
fieldwork and training to implement measures to mitigate climate change impacts
on heritage sites, one in the north east of Tanzania, the other on the coast.
This concentrated on the world-famous Laetoli early hominin footprint trackway,
and a recently identified 19th-century slave trade warehouse complex at Winde,
on the mainland side of the Zanzibar Channel.
Ngorongoro has the famous volcanic caldera filled
with wildlife but also encompasses archaeological and palaeontological sites of
Laetoli and Olduvai showing how our ancestors and relatives lived across
millions of years. Staying the first week at the Endulen Catholic Mission,
about a 27km drive from Laetoli. Breakfast varied between oranges, roast
potato, pancakes, soup, chapati (flatbread), mandazi (doughnut), and banana.
This was supplemented with some honey bought from local Maasai who have hives
hanging from the baobab trees. As part of the conservation area giraffes and
zebra were grazing especially near the watering holes every day driving to
work. While walking, a warden with a gun had to accompany us, as there are
prides of lions presiding over the conservation area. Evidence of elephants
recently passing through could be seen by broken trees, dung and stripped bark.
Laetoli is about 1,700 m above sea level so was up to 30°C during the day but
cold at night needing a warm top. It was the dry season so there were a few mosquitoes,
but I still climbed into sleeping bag at night for extra warmth after tucking
the edges of the mosquito net under the mattress so nothing bigger than 2mm
could get in.
Meeting the first day at the Wardens House for introductions and download of a phone app to digitally capture heritage. The first day involved the visit to the site of the famous early hominin track. The first set of footprints, lying on a cemented ash layer produced by a volcanic eruption and dated at 3.66 million years ago, were recorded by Mary Leakey in 1978. About 40-years later, Fidelis Masao and Elgidius Ichumbaki recorded the second set of footprint a few meters from the earlier recorded site. It is assumed that these were made by Australopithecus afarensis, the same species as the skeleton known as ‘Lucy’, found in 1974 in the Afar region of Ethiopia. The footprints were conclusive evidence that our ancestors were walking upright before brain-size increased.
The original track and later footprint
discoveries were covered in the 1980s by plastic and basalt boulders to protect
them from erosion by people, animals and the rainy season. A new Government
sponsored building with a high roof covering the tracks was under construction during
my visit with plans to uncover the tracks again to see if they have been
preserved. Many tourists leave disappointed because they could not see the footprints,
but the animal track layer can be traced intermittently for about 2.5km up the
valley, which become exposed and eroded during the rainy season. It was an aim
of our visit to map these out making them more widely known that there are more
sites to see and explore so visitors can have a more fulfilling experience.
Following the different layers of rock, it was possible to find this animal track layer from over three million years ago in several locations along the valley. Some footprints have such a wide diameter they must be an elephant relative such as a mastodon, but also similar giraffe and buffalo could be recognised. Dust had to be brushed off to fully expose for photogrammetry. One set of marks has been described as footprints of a predator dragging its kill across the mud. Surrounding softer layers have bone beds of ancestors of the modern megafauna including rhino bone, zebra tooth, warthog tusk and rhino bone. Concrete blocks with letters and numbers carved into their surface mark where hominin bones have previously been found.
The site is on the slopes of a seasonal
river valley where artefacts from a range of different periods can be found
including Middle Stone Age (Middle Palaeolithic in European terms) from 300,000
to 50,000 years ago to Late Stone Age beginning 50,000 years ago and pottery perhaps
from around 1000 years ago was found at one location. Today the pastoralist
Maasai, who arrived around the 18th century, have settlements in the
area and often pass by with their goats and cows curious at the visitors.
Lunch at the site consisted of ugali (maize
meal), rice, hot chili sauce, and stews made from beef, goat or even the small
sprat-like freshwater fish known as dagaa in Swahili. On the first day, still
trying to acclimatise myself, I staggered back to room suffering from heat
exhaustion. A bucket of hot water for a shower was delivered but it was too
late, I had already had my cold one.
Over the week, GPS was used to record positions
of bone, worked flakes of quartz, basalt, chert, and quartzite. Electromagnetic
Methods of geophysics were tested to find evidence of earlier river channels
and springs that could be contemporary with the sites. High-resolution drone
imagery mapped the artefacts that were recorded by GPS so future monitoring may
be able to identify them as they are exposed over wide areas. After collection,
artefacts were 3D scanned back in the Warden’s House.
It was apparent how vulnerable these tracks
are being exposed during rainy seasons by channels cutting the beds, waterfalls
eroding upriver, and the crumbling of the edges and wearing as people walk
across these exposures as they form convenient paths in the dry season. The
importance of recording them as they appear and before they are wiped away was
evident.
About 45km from Laetoli is Olduvai Gorge. There
have been decolonisation initiatives as Olduvai should now be known as Oldupai,
the Maasai word for Mother-in-Law’s Tongue or Snake Plant that is common in the
gorge. The warehouses at the research laboratories at the Leakey camp have extensive
bone collections from previous and continuing expeditions in this area.
The coast
Over the next two days we drove east and
south passing the extinct volcanoes Mount Meru and Kilimanjaro, and through the
Eastern Arc Mountains. Arriving in the port of Bagamoyo, famous for boat
building and being the terminus of the caravan trade in the 19th
century. Winde is about 20km north of Bagamoyo. This is the southern area of
the Wami Delta, a 20km wide area of coast covered by mangrove swamp, beach
ridges, islands and tidal channels that are difficult to navigate without a
boat. Surveying the beach ridges, that have grown seaward over the centuries,
reveal dense concentrations of pottery, mostly undecorated local earthenware,
and stone gravestones dating from the 16th to the 19th
centuries. This suggests that there were important industries here in pottery, salt
and mangrove poles, and perhaps even slaves and ivory.
The area has not had much investigation
until recent studies by Professor Ichumbaki of the University of Dar es Salaam.
Parts of a complex of ruins precariously remain on a sand bar between the sea
and tidal channels of the delta. It’s remote and difficult to reach location
today may suggest smuggling activities to Zanzibar during Colonial rule but we
mustn’t underestimate how linked places were by the sea in the past compared to
road travel today. Therefore, the ruins today could mark an important port for
exporting goods from the mainland to Zanzibar, which lies 35km directly east.
We had to take the two-hour motorboat to
Winde as the land route was impassable due to the rainy season extending into
June this year, part of the unpredictability in recent years attributed to
climate change. Therefore, there were many seasonal lakes that would bog down
the vehicles approaching the site. Using the boat, landing was difficult as the
delta is exposed to the SW monsoon, which is prevalent at this time of year but
there is evidence from the eroding artefacts on the landward side of the site
that and the remains of channels that boats may have harboured with the delta
estuary.
Evidence that these ruins were more
extensive was that more parts can be found 70m lower down on the foreshore
suggesting the beach ridge once extended at least this distance. We also walked
past peat deposits on the beach, further evidence that the delta is continuing
to erode in the present climate. Glass beads and bottles, European porcelain
and gun flints were found eroding on the landward side of the sand bar. Tracks
of a hippo disappearing into the mangroves from the ruins made us pause before
exploring further though these animals are more likely to be sheltering from
the sun in the river channels at this time of day.
The evidence of charcoal making can be seen
while surveying and the bags of charcoal are stacked close to the channels
before being smuggled by boat to Zanzibar. An illegal activity unless the
charcoal maker has a permit. Several large fires were seen when surveying as
this often lights surrounding vegetation. This deforestation exposes the
sediments to extra erosion by rainfall, sea and the tidal channels. We recorded
some artefacts at the back of the ruin and looked at the test pit laid open
from last year to see if the sand in it was from a tsunami or cyclone.
Much of the site had quickly grown over
with grass and shrub since clearing last year so would need clearing again
before droning. However, the use of a multispectral drone revealed changes in
vegetation that could be anthropogenic features. Coring in the mangroves for
evidence of storms over topping the barrier beach was suggested as a method to determine
past cyclones and tsunamis that could have affected the site. Unsuccessfully
trying to persuade a boat owner to let me paddle a canoe upriver to reach the
islands in the delta and examine the stratigraphy in the river cut sections,
Richard suggested to bring fold-out canoes next year.
Packed lunch back on the beach consisted of
potato, roast meat, chapati and roast banana though ants had found our food and
had to be brushed off. For the second day of this, I learnt that washing the
ants off in the sea first was more successful than brushing and shaking. The
rough journey on the way back resulted in numerous wave soakings and early
stages of hypothermia that required the warm hoodie again despite it being
about 20°C in the evening. Back in Bagamoyo, the mosquitoes were great in
number and not afraid to bite so I grabbed dinner from the table on the terrace
and ran inside as the rooms had been sprayed. More coconut is used in the food with
fish when the sea is not too rough for fishing. As the team started to leave,
data was exchanged, goat was barbequed with pilau and kachumbari (onion and
tomato salad).
The final few days were spent surveying easier to reach sites upriver in the Ruvu and Wami rivers continuing surveys from previous years. Being able to keep lunch of left-over goat and banana in a vehicle saved it from the ants. It is interesting how artefacts become older landward with Chinese porcelain and Late Stone Age flakes and hammerstones suggesting differences in sea level and sedimentation. Cultivation ridges were good to look at as the disturbed soil often brought pottery to the surface. This often led to introductions to and welcomes by the farmers, who I think were hoping I was an investor to bring some development to the village. At one point we came to a quarry where a group of Maasai woman doing the washing in the stream who said they had also have come down from Ngorongoro though I suspect their journey with animals grazing took a lot longer than ours.
To break up the journey on the way to the airport in Dar es Salaam, we stopped at the Kunduchi Ruins that have sacred baobabs and graves, some of which still having the porcelain intact in the pillar tombs. The standing buildings are around 18th century though the pottery indicated occupation here from the late first millennium.
The team, funded by the British Council’s
Cultural Protection Fund, involved cooperation between the University of Saint
Andrews, University of Dar es Salaam, National Museum of Tanzania, Ministry of
Natural Resources and Tourism, Ngorongoro Conservation Area Authority (NCAA), Discovery
Programme, and the University of Wales Trinity Saint David.
Dr Edward Pollard
Coastal and Maritime Research Archaeologist
The Discovery Programme: Centre for Archaeology and Innovation
Ireland
Unit 2, Merchants House, 27-30 Merchants Quay, Dublin 8, Ireland,
D08 K3KD
E-mail: edward@discoveryprogramme.ie
18/07/2024
