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Eager Wannabe Aerial Archaeologists Visit Prlekija

Inspired by fantastic aerial archaeology work by dr. John Wells (who uses kites for flying the cameras!), with last summer's discoveries at Newgrange, and with our own chance find at castle Kalec, we went searching for more ancient remains that can be seen only from the air.

The Ministry of Culture of Slovenia maintains a database of cultural heritage that is conveniently shown on this map, sorted by type of heritage and by age. As we were headed to Prlekija in the norheast, we sifted through the database and chose some spots with possible Roman archaeology that could be photographed from above - and to test the new KAP kite, a dr.agon BW90 mini delta ...

A dr.agon D90BW mini delta in action

From first to fourth century CE Prlekija was a part of a fertile, agricultural area between Poetovio (today Ptuj, Slovenia) and Carnuntum, the 'capital' of the province of Pannonia. There were Roman outposts, villages, military camps, and villae rusticae dotting the landscape, and a network of roads connecting them.

Today this part of Prlekija, northeast of Ljutomer, is an intensive agricultural area; most of archaeology is long lost, ploughed over and over, and only occasional finds of shattered pottery, tegulae and the like remind us of the times past. So our plan was simple - find a spot that has shown "archaeological potential", lift a kite with a camera - and hope for some luck!

Typical fields of Prlekija, as seen from a kite

And this is how it looks from above. Different shades of green and brown, young wheat and just planted corn, streaks of the plough. Nothing much to see - except ...

The same field with brutally enhanced contrast.

... Except if you push the contrast to the limit, and some things become visible. A dark wavy shape and a bright straight line.

As the interpretation of aerial photos goes, the light and dark areas on a ploughed field (without vegetation) differ in moisture. The dark areas are wetter than the surroundings, and light ones are drier. The reason for this difference is in the compactness of the soil; the darker ones are more loose and thus retain more moisture, while the lighter ones are more compact and dry out sooner.

So what are those? Turns out that the dark wavy patch is actually a fossil riverbed, an ancient meandering stream silted up long ago, even before the river regulation and field melioration works. The loose soil is deeper, so it retains more water and looks darker

And the light straight line? That's most probably an ancient Roman road! It's hidden below the field, but its hardened surface still makes the soil above it to dry faster. The straightness of the line is very much in line with Roman roadworks principle - make it straight!

Where there is vegetation, the correspondence is sonewhat reversed. In a more compact soil the plants struggle more, so they are lagging a bit in growth and they appear darker, whereas in deeper soil they grow better and appear lighter.

Adding weight to to Roman road hypothesis, the direction of the purported road seems to link two other areas of greater archaeological potential from the Roman times, as seen on the map of cultural heritage of Slovenia (red dots and areas are Roman, purple are Iron Age sites, others are medieval and modern); the possible road is overlaid in light blue and it goes as all Roman roads go - perfectly straight (the area on the photos is around the red dot in the middle): .

Straight as ... well, as a Roman road!

The fossil riverbed was confirmed before, as seen on this map kindly provided by dr. Mija Toplicanec from the Institute for the Protection of Cultural Heritage of Slovenia (the site is traced in yellow, the orange squares show the areas where the archaeological field exploration was done, and blue lines denote ancient riverbeds):

Ancient rivers of Prlekija and archaeological field walks.

The riverbed seen in our aerial pictures can be seen at the lower end of the area (traced in yellow).

We did some field walking too, to find some ancient pottery or whatever, but nothing much was found - a couple of pottery shards that are most probably Roman:

Pottery shards collected from the field. The glazed one is most probably medieval, others can be Roman.