Setting and Landscape

5.2 Setting and Landscape

The south-western coastline of Unguja comprises a series of peninsulas and open bays facing out towards the islands of Menai Bay. The archaeological settlement of Unguja Ukuu stands at the base of the Makime peninsula, with a beach on one side, and a mangrove creek on the other (Horton and Clark 1985; Juma 2004). The underlying geology of the area is of reef-limestone, overlain by white subsoils and probable-marl sediments close to the shore, and red laterite soils inland (Caistor 1968:

14). West of the site the soil transitions into apparently semi-exhausted uwanda soils (shallow loam on coral or limestone), and further north by shallow red soils, whilst Uzi Island, to the south east, is again thinly covered by uwanda soils (Caistor 1968: 14). The nature of these soils means that Unguja Ukuu itself can support more successful agriculture than most of the surrounding region, and the immediate area is still farmed extensively, if not intensively, today (Caistor 1968; Juma 2004; Horton forthcoming).

131 Figure 5.1 Map of Menai Bay in south-west Unguja, showing Unguja Ukuu and known proto-Swahili/Swahili sites. Background DEM is composited SRTM and digitised UKHO hydrographic charts

The open beach of Unguja Ukuu faces southwest into Menai Bay, and is composed of fine white coral sands fringing above a broad coral shelf which stretches from Ras Kigomani on the west, to the southern point of the Makime peninsula. This coral shelf appears relatively flat and even, sloping gently away from the beach into Menai Bay for around 300m, before dropping abruptly away into deeper open water. For the most part the coral is covered by a very thin layer of silt, and although its leading edge floods quickly with the rising tide, the water close to the beach remains shallow until late, with the beach itself only flooding within 2 hours of high tide (Nyandwi 1999). Several small hotels and beach houses, a daily fish-market, an unfinished mosque, and an unfinished museum have been built along the shoreline of Menai Bay, and in the past decade the low-lying area inland of

132 the raised beach has been cultivated by local farmers for use as cassava fields and a banana plantation.

Figure 5.2 Composited Google Earth satellite imagery in GIS, showing key features of landscape around Unguja Ukuu and Menai Beach

The modern village of Unguja Ukuu lies north of the main archaeological settlement, along a densely wooded ridgeline which descends from inland towards the neck of the peninsula. A Customs Department naval camp built in the 1990s, known as the KamKam, occupies the southern end of this ridgeline, covering an area of stone foundations identified by Horton and Clark, and excavated by Juma (Horton and Clark 1985; Juma 2004). Most of the archaeological site lies on the landward side of the narrow neck of the peninsula, extending from the open beach of Menai Bay on the west to the mangrove creek, and north onto the ridgeline. It is possible that given the apparent depth of

133 archaeological stratigraphy observed here and the results of Juma’s excavations, the ridgeline has been enhanced by occupation and subsequent deposition, and should be considered a potential tell site (Juma 2004). Horton and Clark identified middens at the base of the ridge, on the neck of the peninsula, and their test pit UU1 apparently cut into one of these (Horton and Clark 1985: 12).

These middens and associated pottery scatters also marked Horton and Clark’s estimated southern limit of the site. Expansion of the KamKam in the past decade has involved the bulldozing of this area, although as the results below demonstrate this has not destroyed the archaeological remains entirely.

Figure 5.3 Georectified elevation model derived from SRTM GDEM v3. Note that archaeological settlement at Unguja Ukuu lies at base of elevated ridgeline running inland

134 East of the site a dense mangrove creek with deep silt sediments runs north from Menai Bay between the Makime peninsula and Uzi Island, before trending north-east into the dense vegetation and shallow red soils of Jozani Forest, one of the few remaining, and the only protected area of rainforest on Unguja (Punwong et al 2013). The shoreline facing this creek is marked by a narrow strip of beach sand, transitioning with the mangrove growth into deeper peat and silt sediments into the channel (Punwong et al 2013). Large quantities of pottery were reported by Horton and Clark (1985: 12) along this shoreline, and while much is still visible today, dumping of bulldozed spoil into this mangrove fringe appears to have changed the topography and makeup of this material.

South of its narrow neck the peninsula extends a further kilometre and a half, widening and rising to around 8m in height. The area is cultivated, with ridge and furrow all along its eastern bank. A tomb and building rubble halfway along its length mark the only recorded archaeological remains on the peninsula (Horton and Clark 1985: 12). A small rocky harbour used by local fishermen lies at the south-eastern tip of the peninsula, and a row of electricity pylons from this point across the channel to Uzi Island mark out an informal low-tide causeway to Uzi Island.

Figure 5.4: Facing east across mouth of creek towards Uzi Island from Makime Peninsula. Electricity pylons to right of cliff mark intertidal causeway. Photo by author (2013)

135 Figure 5.5 Photo of Menai beach at Unguja Ukuu, taken at mid-tide, facing north-west towards Ras

Kigomani from Menai Bay Beach Bungalows (Photo by author)

Figure 5.6 Photo of Menai beach at Unguja Ukuu, taken at low-tide, facing south-east towards Makime Peninsula from Menai Bay Beach Bungalows (Photo by author)

136 Figure 5.7: Areas affected by bulldozing and shoreline retreat

Locals reported significant beach erosion at Unguja Ukuu, both during fieldwork for this thesis and during Horton and Clark’s survey in 1984, and Horton has described substantial tidal damage to the

‘Arab House’ since his first visit (Nyandwi 2001; Horton and Clark 1985; Horton pers. comm.). To test the possible extent of this erosion and to determine potential taphonomic changes to the site, a GIS comparison was carried out between recent high-resolution QuickBird imagery and archived CORONA imagery captured in 1963, with additional reference material from British Admiralty hydrographic charts dating back to the nineteenth century (UKHO 1875a, 1881, 1897, 1900, 1910, 1916, 1964). The comparison of satellite imagery indicates that the lower line of the beach has receded by around 5-10m over the past 50 years, but the comparison of Admiralty hydrographic charts does not indicate significant variation between the nineteenth and twentieth centuries

137 beyond that expected through improving cartographic accuracy (Figure 5.7). A study of beach erosion in Tanzania and Zanzibar, published in 2001, concluded that the most significant cause of beach loss at Unguja Ukuu itself has been the quarrying of sand for road construction since the practice was legalised in the 1990s (Nyandwi 2001). The removal of sand and subsequent loss of anchoring vegetation has destabilised the beach, and the report estimated that over the two-year period of 1994-1995, the land-loss at Unguja Ukuu totalled around 5m (Nyandwi 2001: 126). This estimate helps narrows the date range of the erosion observed in the comparison of satellite imagery from an initial estimate of 50 years (between 1963 and 2013), to a far shorter period of 7 years between 1994 and the publication of the report in 2001. Although local reports of erosion prior to this date should not be dismissed, it seems that the most significant loss of beach material has been quarrying and consequential destabilisation, whilst the comparison of hydrographic charts indicates that prior to this the beach was relatively stable for at least 200 years between the nineteenth and the mid-twentieth century.