6.3. Geophysical survey results cont'd

Field 761 (Site 1/5)

This field is situated on a north-east facing hill slope, and slopes quite steeply away from a road and farmhouse positioned to the west. Results of the magnetometer survey showed relatively even readings across the survey grids, with few potential features visible (Figs 6.19 - 6.20). A faint curvilinear anomaly in the west and south of the survey was noted [1], running in a south-east and easterly direction. Similar positive anomalies, running across the survey area [2, 3], indicate that the features are of agricultural origin, possibly a result of the ploughing of earlier terraced field boundaries. A sub-rectilinear feature [4] was located at the west end of the survey area, and a large positive anomaly was noted along part of the eastern edge of the survey [5]. Although it is possible that these suggest archaeological features, the discrete nature of the anomalies on the fringe of the survey area provides insufficient context for such an interpretation.

Field 855 (Site 1/1)

This survey was carried out on a low plateau to the east of Castro Outeiro dos Picotos, overlooking the river Cávado. Results of the magnetometry survey showed an overall confusing set of positive and negative readings, probably produced by the magnetic nature of the surface geology (Figs 6.21 - 6.22). One potential linear anomaly was noted running in a north-east direction from the south-west corner of the survey [1, 3]. This may relate to a slight sub-circular anomaly in the southern part of the survey area [2]. A large set of positive readings were noted in the south-west corner of the survey area [4], probably related to the linear feature to the north-east, or it could be a product of ferrous material scattered along the modern field boundary.

Castro site at Terroso

In total, seven grid squares of magnetometry were undertaken on the castro at Terroso, to record part of the unexcavated settlement, and to provide a control with which to compare other geophysical survey results (n.b. there are no images available for the survey at Terroso, but all the data can be downloaded from the digital archive). The survey located a number of sub-circular and sub-rectangular anomalies associated with dwelling structures. A number of closely spaced circular features, around 7m in diameter, could be seen in the south-west part of the survey. In the central grids, a rectangular anomaly was noted, together with a circular feature with a curvilinear negative anomaly attached to it. One other circular feature could be seen in the east of the survey area, together with a broad curvilinear band of positive readings, possibly a defining and enclosing wall. In a survey grid separated from the main survey area, 10m to the north-east, two further circular features were produced by the readings, directly over the excavated remains of round houses in the western part of the castro.

6.3.1 Discussion

The results of the geophysical surveys described above were generally rather disappointing. Whilst most of the surveys suggested that the areas identified as probable sites on the basis of surface ceramic distributions did have subsurface features present, the results were insufficiently clear to aid interpretation. The two possible sites examined (Sites 2/27 and 2/31) did also reveal features, encouraging confidence in the identification of sites on the basis of even low density ceramic concentrations.


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Last updated: Sat Dec 30 2000