Magnetic surveys

Geophysical prospection in Novae is difficult due to inaccessibility of significant areas of the civil settlement (canabae) and a specific topographical and geological conditions. Yet, the systematic and carefully planned survey campaigns produced results which can be used during the planned excavations.

Dense forestation in some parts of the fortress’ and its surroundings and the development of modern summer housing around the site limited a wide scale magnetic survey to some chosen sections. The best accessibility offers the southern part of the annex (the area adjacent to the east of the fortress) and the rear part of the fortress (retentura). The results obtained from the latter, where we expected a more or less regular pattern of the barracks, may have been used as a comparanda to the results from the measurements in the extramural area.

Prospection in hard surface conditions

Prospection in the difficult surface conditions

The prospection was carried out with the use of a fluxgate magnetometer, Bartington Grad 601-Dual, within the grids set up with a total station.

In 2011 some tests were made within the area of the retentura and the principia. Their purpose was to determine whether the application of remote sensing methods would produce successful results. After receiving positive effects, we decided to carry out the magnetic survey on the each area which was accessible. Smaller fields were investigated with another, electric resistivity method. The vast area within the annex was investigated in 2012, and finally the smaller fields in the western part of the canabae in 2013. In 2014 we focused on the Ostrite Mogili site and some smaller settlements in its vicinity.

canabae2012

Areas covered by the magnetic surveys in 2011-2012

Within the annex of Novae a survey grid of 30 × 30 m polygons (23 in all) were laid out, covering the total area of ​​over 2 ha. In 2012 the magnetic prospection was conducted with a Bartington Grad 601-Dual fluxgate gradiometer and a cesium magnetometer G-858 Magmapper with GPS RTK. A micro-relief map covering the area inside and outside the walls was also made with the aid of the GPS RTK system.

The survey revealed a number of different types of anomalies, some of which correspond to the features visible on the surface. A number of anomalies not visible on the surface can be related to some architectural structures. We were able to distinguish linear anomalies, zones of interference, dipolar and single point positive anomalies. Linear anomalies could be remnants of ancient retaining walls forming a system of levelling terraces, or modern parceling of arable fields. Their origin is  the subject of  further investigations.

Magnetic prospection on Ostrite Mogili site

The magnetic prospection on the Ostrite Mogili site in 2014

The linear anomalies intersecting at a right angle can be interpreter as the remains of ancient buildings. In some places complementary methods (e.g. ERT and earth resistivity) allowed to understand better the nature and origin of the anomalies.

Some magnetic anomalies were linked with disturbances caused by modern infrastructure and looting activities.

In 2014 the magnetic survey was carried out on the site of Ostrite Mogili, to the east of the fort. The measurements were made on an accessible open area, yet crossed by series of metal fences and paths. The surveyed area covered around 3 ha revealing a series of anomalies that indicate the presence of some subsoil architectural remains.

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