Knossos Roman Geophysics - 2018

Knossos Roman Geophysics. Daniel Stewart (Leicester) and Jennifer Baird (Birkbeck) report on a fourth and final season of geophysical investigations at Knossos with the overall goal of providing a working knowledge of the urban layout into which excavated but largely unstudied archaeological materials from BSA excavations of Roman Knossos can be placed (Fig. 1).
Four seasons of geophysical prospection suggest that there was no overarching orthogonality imposed on the city in its latest period of occupation; there were at least 3 different orientations to the layout, probably driven by topography. Earlier work, further supported by the 2018 season, strongly suggests that Roman inhabitants of Knossos used Minoan architectural features in the layout of portions of the city (primarily close to the river, and immediately west and north of the Minoan Palace). The broader implication is that the large-scale landscape interventions of the Bronze Age impacted the inhabitants of the Roman city thousands of years later.
Four seasons of investigation also demonstrate the efficacy of geophysics within this landscape. Aggregate data offer a meaningful and worthwhile way to build up a larger picture of the urban topography. In the first two seasons a wide area of the valley was covered with magnetometry, while seasons 3 and 4 focused on targeted examination with Ground Penetrating Radar (GPR) and tests of resistivity. The aims for 2018, were: continued targeted use of GPR over the survey area, together with systematic GPS mapping of known standing remains; further refinement of the ‘orthogonal’ plan in centre of city; further exploration of the eastern, northern, and southern edges of survey area, with the aim of tracing road networks and a possible interface between city and countryside; and deployment of additional landscape-scale investigative techniques such as targeted T-LiDAR and photogrammetry.
The GPR equipment used was a GSSI UtilityScan DF, using two digital antennas, one providing a detailed snapshot up to 1m in depth, the other coarser data down to 5m. The project created 1,618 depth profiles in 2018 (809 at each of the two frequencies). As in previous years, we also used a Leica ICON 60 GPS base-station with a GS08plus Rover to help locate both the grid layouts for the geophysical survey and to record significant structural features in the landscape. The base station control-point coordinates are: 35°18’1.50684”N; 25°9’36.03965”E; altitude 136.044 m.
In 2018 a further 1.5 ha were covered with GPR, making a total of 3 ha of GPR coverage, mostly within areas already covered with magnetometry (Fig. 1). Total area coverage for the geophysical survey was around 17 ha. Hood and Smyth estimated the size of the Roman city at 50-60 ha in size, while Whitelaw suggests 70 ha based on the results of the Knossos Urban Landscape Project (KULP). Areas were investigated using an ‘aggregate’ approach, covering small strips of adjacent territory, rather than large open areas.
Although interpretation of all results has yet to be finalised, the data revealed are intriguing: rectilinear features are evident, usually in the 1.5-2.5m depth range, and there may also be evidence of activity areas, roads, and some terracing, as indicated in the overall interpretation (Fig. 2). This overall picture of the city is increasingly complicated, but the general conclusion is clear: this is a dense urban landscape exhibiting multiple, intersecting layouts.
In the ‘Northwest Area’ of the city (where survey began in 2015), GPR in 2018 allowed the identification of many more rectilinear features, and the extraction of much more detail (Fig. 3). There appears to be evidence of at least three courtyard structures, probably domestic, and a range of rooms/features. While there are no clearly identifiable streets, it is possible that further analysis of the data may lead to the identification of major streets in this area.
The so-called ‘Northeast Area’ was previously identified as an area where multiple grid layouts intersected and that can be seen in the 2018 results too (Fig. 4). Unlike the broadly north-south orthogonality of the area further west, this side of the valley (which is more heavily terraced), has a distinct northeast-southwest axis. The central block here shows evidence of two distinct layouts: a more North-South axis to the west and a Northeast-Southwest layout to the east. The North-South layout is also evident further west, currently on a terrace above the central block. The different layouts here probably reflect ancient topographic differences and evidence of terracing, perhaps originally Minoan in date, given the broad alignment with Minoan features.
Around the remains of the Civil Basilica, more of an apsidal structure (with walls partially extant) was revealed. It is roughly on the same alignment as the rest of the city grid in this area, which runs North-South (Fig. 5). There appear to be significant structures around this building to the north and west, but these North-South orientated structures are not on the same alignment as the remains of the Civil Basilica. It is possible that the Civil Basilica overlies an earlier orthogonal area of the city, suggesting evidence in the geophysics results of phasing here. More refined analysis of the geophysical data may help untangle the various phases based on depth of response.
Continued exploration with the GPR in the area of the Villa Dionysus shows another courtyard house on the western terrace above the current villa (Fig. 6). To the south there is clear evidence for a street in both the magnetometry and the GPR data. North of the villa there is another possible courtyard structure, or an extension of the villa itself, given its proximity.
The area around the Makryteichos provided perhaps the most immediately satisfying GPR data in 2018 (Fig. 7). As previously suggested, the standing wall is probably the back of a terrace supporting a stoa and associated structures. GPR results not only show most of the stoa, but also record five of the column bases on the interior colonnade. Also visible is the eastern return of the stoa wall, and, to the north, an East-West and a potential North-South street, and a large rectangular structure.