Month: July 2011

Excavations in the Lower Town started in Operation T yesterday, despite a heat wave that sent temperatures climbing past 45 degrees Celcius (that’s 113 degrees Fahrenheit).

Operation T is where we expect to find the remains of private houses dating the Assyrian period. The operation is located in the southern part of the site, not too far from the line of the fortification wall that once ringed the ancient city.

We first became interested in this area when our magnetic gradiometry surveys of 1999 revealed a series of long, parallel linear features which we interpreted as the street system of Assyrian Tushhan. We briefly excavated a small test trench, Operation M, in 2004 across one of the linear features, confirming our basic assumption that these were streets lined with domestic structures.

Although the recovery of private houses was one of our long-term goals, it wasn’t until this year, with the completion of two major areas of excavation in 2010, that we had the resources to devote to a larger pilot project excavating the private houses in the southern lower town.

As you can see in the photograph above, the fields here (recently burned) are pretty featureless. You can see the scars made by agricultural plowing, but the archaeology is buried under an otherwise flat, uniform surface. We have already conducted some electrical resistivity survey (maps to come!), selected an area for excavation, and started to remove the topsoil. The modern plows tend to destroy the top 30-35cm of the archaeological deposits, but we expect to find the Assyrian houses immediately beneath this layer of plowzone.

The digging crew started to arrive a few days ago and we start the excavations tomorrow, so all the months of planning are finally at an end.

Dirk Wicke from Mainz University and three of his students, Judith Dosch, Fabian Heubel, and Sarah Reisel, as well as an archaeology student from Britain, David Astbury, have arrived. Our senior Turkish colleague, Kemalettin Koroglu from Marmara University is also here now, having driven across the country from Istanbul to join the team. We have three more excavators still to arrive, but the digging is soon underway with 35 local workmen meeting us at the site at 4:30am tomorrow.

Much of the day will be spent getting the equipment out of our depot, setting up the field camp (everything from tents to the outhouse), organizing the workmen into teams, mending equipment, taking preliminary notes, and cleaning up the old excavation areas. We have already set out some of the grid points for the new excavation areas, but after a year of weathering, we have plants, trash from a year’s worth of picnics on the mound, and backfill to remove from our old excavations. We probably won’t break new ground until Wednesday, but it still feels good to get started.

Tomorrow we will concentrate all our efforts on the Bronze Palace area and then shift workers and energies to the lower town on the following day. It is important to prepare the digging areas carefully. By the beginning of the next work week (that’s Saturday for us), we should be deep into the real archaeological deposits having cleared away the surface debris and plow zone.

I’ll post some photographs of our first morning at work so you can get a sense of what it is like. A few things are nearly certain: 4:30am will have a cool breeze, the sunrise should be spectacular, and there will be a buzz of anticipation in the air.

As you know, we have been conducting electrical resistivity surveys on the high mound at the western edge of the Bronze Palace. In past seasons, we have used a different subsurface geophysical survey technique (magnetic gradiometry) on three separate occassions to try and map the citadel mound. The results have been poor, in part because the stratigraphy of the citadel mound is very complex. Each new occupational group at Ziyaret Tepe has disturbed the remains left by the previous occupants. In our case, the Medieval period villagers dug hundreds of pits into the citadel mound, storing grain and other commodities, and eventually filling the pits with their trash.

This season, I wanted to try a different technique on the citadel mound using electrical resistivity in the hopes that this technique, which in the past has provided us with more detailed maps than the magnetic surveys in the lower town, might provide interesting insight into the western half of the Bronze Palace.

Here are some of our early results from 2011.

Not exactly obvious to the untrained eye. In fact, it is not exactly obvious even to the trained eye what is going on here – this is a difficult dataset! The square represents a plan of a 20m by 20m grid, laid out with the grid point N1000 E1110 in the southwestern corner. Each box represents a measurement of resistance (in ohms) at a given point on the citadel mound. Each square (or pixel) is 50m by 50cm. In broad terms, the dark areas have a high resistance; the light areas have low resistance. The red squares are those with the highest resistance.

At Ziyaret Tepe, pits and mudbrick walls tend to retain moisture well, so they have less resistance to the passage of electricity. Remember water is a great conductor of electricity (which is why you don’t plug in your radio perched on the edge of the bathtub) so moisture content is an important part of our electrical resistivity maps. The soil inside and outside of the mudbrick walls tends, in general, to have slightly higher resistance, while compacted soils (like pathways and streets), cobbled surfaces, and large stones tend to have the highest resistance.

My interpretation of this map suggests that the Medieval pits have again badly damaged the underlying Assyrian walls, which should appear as linear light shaded features. There are hints of walls, but it is hard to point to a distinct plan. There are also vaguely circular features which may be the results of pits. All in all, it is a disappointing plan except for two single points, close together which gave extremely high resistance readings at the place where I have put the blue circles. The resistance here was not high enough to suggest a void or open space (such as a partially-filled well), but more like a very large stone, a coarse gravel fill, or a small, highly compacted surface. It is probably worth spending a few days digging here in order to identify the source of the anomalous readings.

This process, commonly used in the geophysical surveys, is called “ground-truthing”. If these places turn out to be interesting archaeological features, we can expand the area of our survey to find other, similar anomalies.

Digging starts on Tuesday, so perhaps we will know soon what these high resistance points represent.

With some expert troubleshooting from Brad Rice and Chris Martin in IT at the University of Akron, we seem to have overcome our connectivity problems with the blog! Thanks to both of you for your help. As usual, the UAkron IT department comes through.

This photograph shows Willis Monroe and our driver, Mehmet Tekin, helping with a geophysical surveying on the citadel mound two days ago. We are, in effect, trying to find the western edge of the Bronze Palace before we start the excavations. Our efforts in previous seasons have been entirely concentrated on the eastern part of the building, so we need to expand our explorations.

As I mentioned earlier, the Bronze Palace was built, in part, on a thick platform of mudbricks which served as a strong foundation for the building. One clue we have about the location of the western edge of the palace is a steep slope about a meter high and approximately 80m (=240 feet) west of our current excavation area. Since the mudbrick platform should erode more slowly than other materials, it makes sense that this steep erosional escarpment might just be the edge of the platform for the palace.

To test this hypothesis, we are trying to map the ancient subsurface features, like the walls of the palace, using electrical resistivity. This is a geophysical survey technique in which we pass an electrical current underground between two probes. A second set of probes measures the grounds’s resistance to the flow of electricity. Buried walls affect how easily an electrical current flows underground between two points and, if we collect readings systematically along our site grid, we can map them and “see” features below ground without excavating.

The frame that Willis and Mehmet are inserting into the ground holds two of the probes and a long yellow wire connects to two distant probes, some 50m away. These probes create the electrical field and measure the subsurface effects. The box on top of the frame collects the measurements; we have sophisticated mapping software on our field laptop that allows us to convert the resistance readings into a map of subsurface features.

As you can see in the photograph, there is nothing visible on the ground to guide our excavations, so we rely on subsurface geophysics to help us choose the best places to dig.

For any UAkron students who might be reading this post, I will be teaching my Archaeogeophysical Survey course again in the Spring of 2012. It’s a fun class and you never know where it might lead you.

A few of you may have noticed that my last two blogs came up in pieces. In fact, it took many attempts across several hours to get the previous blog to load at all. This one is being sent from the town of Bismil about 25 minutes away from Tepe.

We are still having difficulties with our electrical supply. Turkey runs on a 240V system, but our regulator in the dig house is showing that we are only getting about 150-170V into the house. Some of the rooms in the compound effectively have no electricity and the power goes out completely about ten or so times a day. This appears to be a problem across the entire village, but it does make our technology-driven work more challenging.

We are also having difficulties with our wireless connectivity, which is intermittent at best. If you don’t hear from us for a few days, don’t despair, we will get updates to you as soon as possible. Field conditions are often a bit on the rough side, but we are still making good progress with the archaeology, despite the technical difficulties.

On the bright side, today’s survey data look really interesting; more to come soon on that subject!