From the Site Diary: Approaching Songo Mnara


Songo Mnara is not as easily accessible as Kilwa Kisiwani; travelling by boat from the port at Kilwa Masoko we approached a picturesque fishing village at Sangarungu, palm frond makuti structures emerging from a clearing within the mangroves and palms on white sands. Sangarungu is a working fishing village and despite the seemingly remote location by British standards, there’s a small shop for the fishermen selling Fanta Passion and other supplies, ice is shipped from the mainland to preserve the recently gutted fish on wooden platforms just off the beach.

The journey to Songo Mnara

This route is only accessible in low tide as the boat moors just offshore, so you have to wade to the beach. Passing through Sangarungu, white sand stuck to our wet feet as we walked through palm plantations and mangroves, curious monkeys crashed through the trees, just out of sight. The sandy path sloped downwards into the Mangrove swamp, the barrier between the sandy island of Sangarungu and Songo Mnara; at low tide we walked down into a cutting, into the dense shade of the mangroves, twisted roots emerging from the sand.

We waded through the shallows for 150m to Songo Mnara, to the sound of water being pushed violently ahead by our legs, solitary mangrove fruits floated past poised to anchor into the sand and fill in the gap left by the cutting. The brave and adventurous might try to keep their shoes on and their feet dry at low tide, by traversing the mangrove roots at the edge of the path. At higher tide, we waded into chest deep clear water, despite the organic blackness of the mangrove sediments; carrying our bags on our heads to keep them dry as small shoals of fishes swam past. Emerging on white sands we reached Songo Mnara, on the very edge of the intertidal zone.

Harbour Songo Mnara

At high tide, when the tide is too high to wade through the mangroves from Sangarungu, we instead approached a shallow cove of clear blue water to the north of Songo Mnara. Coral rocks cropped up through the water hiding small shoals of small black and white tropical fish, mangroves, visible at low tide, peering through the waves, protecting the natural inlet; we scrambled from the side of the boat up the coral bluffs, entering through a thicket, emerging onto white sands studded with tall Coconut palms.

The ruins of Songo Mnara lie on the edge of a large Coconut palm plantation, pale grey ruins surrounded by lush green vegetation. At first, you can barely make out the crumbling coral walls peering through trees and lianas, but then you begin to see the walls emerge, picking out buildings, seeing the city develop before your eyes. Every now and then, a loud crack punctuates the silence, as a Coconut palm branch falls. Whilst the abandoned buildings decayed, huge Baobab trees sprung up next to the ruins, growing stronger, almost eclipsing the monumentality of the buildings; introduced by the inhabitants of the buildings, their presence is a natural reminder that this was once a busy urban trade town.

Baobabs and Buildings

Songo Mnara Palm Plantation


Day of Archaeology 2014 – Counting Phytoliths from Songo Mnara, Tanzania

This is my first blog post, for Day of Archaeology 2014!! Right now, I spend my life counting phytoliths – over 3500 phytoliths so far….What’s a phytolith and why does it get me out of bed and into the lab before 7am? How did you not realise this was such an exciting archaeological technique? Phytoliths are a bit like plant negatives; essentially the plant absorbs monosilicic acid (H4O4Si) from its water supply and during transpiration as the water ‘leaves’ the plant, the monosilicic acid becomes solid opaline silica. It has to go somewhere, so it fills in gaps within the cell structure of the plant. These gaps are either within the cells, or surrounding the cells, making silica negatives of the internal cell structure. Not all plants make phytoliths though, just like not all plants preserve well as charred plant macrofossils, and not all pollen grains enter the local archaeological record or preserve well. Plants have to degrade in situ for the phytoliths to be included in the archaeological record, no technique is perfect. But the key is, that phytoliths are well preserved in a variety of contexts and can add to our understanding of plant use; not only on sites with poor preservation of plant macrofossils and pollen, but also in contexts where plant remains may not have entered the archaeological record following charring. For example, organic crafts such as grass or palm matting may not be preserved by charring and therefore might be invisible on archaeological sites without waterlogged preservation. These may be visible through phytolith analysis if they have degraded in situ. To help identify diagnostic phytoliths I collected lots of plant samples from the field and I’m now creating a phytolith reference collection in the lab. It’s not a magic bullet to help us understand plant use in the past, but it is pretty cool! I’m working on late 14th to early 16th Century samples from Songo Mnara, a Swahili stonetown in Tanzania, part of the Songo Mnara Urban Landscape Project [1]. Songo Mnara is part of the Kilwa Archipelago and it’s linked to other settlements and islands along the East African coast through the Indian Ocean Trade network. Songo Mnara has truly amazing preservation of stone buildings!! To get to the site you have to take a Dhow from Kilwa Masoko with a guide and once you arrive on the island you have to wade through a tidal Mangrove swamp which can be anything between ankle deep and chest high! It’s off the beaten track, for sure.

Blog 1. Songo Mnara Buildings

© Hayley McParland-Clarke 2013

During the 2013 excavation season, two types of structure were excavated; a stone house divided into rooms and a collapsed wattle and daub structure, which appeared open plan. Initially it was thought that the monumental stone architecture in the town was standing in an open area, but extensive test pitting by Dr Fleisher combined with Geophysical and Magnetometer survey[2] revealed the presence of concentrations of daub within this space. Excavation exposed two wattle and daub structures with comparable finds assemblages to that of the stone structures. The phytoliths I’m looking at today come from Trench 32, one of the daub structures. Spot samples were taken across the entire packed sand floor surface of the structure on a 1m grid, in order to assess whether phytolith analysis can be used as a tool for spatial analysis and to understand the use of plant materials within the structure. Samples were also taken from the ‘outside’ of the structure in the open area to identify clear differences in the phytolith assemblage between ‘inside’ and ‘outside’ and to see if it was possible to recreate the environment immediately adjacent to and further away from the structure.

Sampling for Phytoliths at Songo Mnara © Hayley McParland-Clarke 2014

Sampling for Phytoliths at Songo Mnara © Hayley McParland-Clarke 2014

I’m really hoping that we’ll be able to see activity areas within the structure through the plant assemblage, for example food preparation areas or areas of matting. It may be possible to identify construction materials such as wood, or roofing materials such as palm thatch. I’m also hoping to see evidence of Indian Ocean Trade through phytoliths from imported edible plants within the assemblage, but as with all archaeology I can hope for lots of things, it doesn’t mean it’s there! We also sampled the stone house, which is really interesting, because it has clear rooms within it, whereas those divisions weren’t clear when excavating the daub structure. Phytolith analysis might enable us to see the limits of the daub structure by providing an ‘inside’ and an ‘outside’ botanical signature. The process of counting involves using a high powered microscope at x400 magnification to identify phytoliths, photograph them, measure them and count them. I count around at least 250 per slide, which means that I’ve counted thousands from this site so far, and I’ve a lot more to do! Phytoliths are 3D objects, but when you’re looking down the microscope you only see the 2D image, which means that you have to remember that each phytolith type might look different depending on which angle you’re looking at it from! Phytoliths aren’t always round like pollen, in fact they’re frequently not round at all, they come in all shapes and various sizes! Although lab work is often thought of as completely different to fieldwork, it’s sort of the same. I search through transects on the slide, much like layers of stratigraphy looking for microscopic evidence in the form of phytoliths rather than artefacts. It can take a long time, it’s systematic and sometimes I don’t find anything of interest. Recording stratigraphy on site tells you a lot about site formation processes and human actions, likewise recording information about the slide assemblage is useful. For instance, lots of phytoliths which are still articulated suggests that there was little bioturbation, or lots of microcharcoal might suggest burning episodes.


© Hayley McParland-Clarke 2013

I’m on my last few slides from this pilot study now, and I’ve started to get an idea of what’s happening in the structure which is really exciting. Each phytolith assemblage has a different character, which suggests that the spatial approach might be working!! I can clearly see a difference between the assemblages from the floor surface ‘inside’ the building and the outside; I can also see variations across the floor surface within the structure. Future research will focus on the comparison of the stone house and the daub structure to see if there’s a difference between the uses of each structure. I also hope to look at some of the open area samples to try to understand how the urban landscape impacted on the local environment. Follow my progress and find out more about phytolith analysis, archaeobotany and archaeology by checking in here every now and then, or follow me on twitter @hayley_mcp.   [1] Managed by Dr Stephanie Wynne-Jones and Dr Jeff Fleisher, funded by the NSF and AHRC. [2] Welham, K., J. Fleisher, P. Cheetham, H. Manley, C. Steele, and S. Wynne-Jones. 2014. Geophysical Survey in Sub-Saharan Africa: Magnetic and Electromagnetic Investigation of the UNESCO World Heritage Site of Songo Mnara, Tanzania. Archaeological Prospection.