The nine areas in Denmark selected for the aerial archaeology project, which is scheduled to run until 2013.

Vestiges of ring ditches which have encircled very small mounds in the Early Iron Age. If Iron Age people had not dug these ditches around the mounds where they buried their dead, we would have had no chance of finding these burial mounds.

The round bright spots are traces of burial mounds, which have been ploughed and smoothed over centuries. Also pictured are a couple of preserved burial mounds. About a quarter of the mounds that once existed are preserved today. The number of burial mounds helps us form an idea of the population size in the Late Stone Age and the Early Bronze Age, and archaeologists are constantly discovering more of these mounds.

The bright stripes, which almost form a fluorescent grid pattern, are vestiges of embankments that surrounded small fields in the Early Iron Age, around 2,000 years ago. The embankments were built using a material that was different from the rest of the field, and sand has drifted over them. This means that they dry out quicker than the rest of the field in spring and autumn, and that makes it possible for us to see them. They can stretch over several hundred acres, but often several flyovers are required to spot them.

Vestiges of two enclosures, which may have surrounded remnant houses from the Iron Age. In the small enclosure, we see an entrance but we can only guess what it is that has been enclosed. All we can see are a few small pits. We know about enclosed farms and villages from the Iron Age, and this find could be a vestige of a deep trench for such an enclosure. It may also have been used as fencing for sheep or cattle, in which case they may be only 100-200 years old.

Vestiges of Early Iron Age remnant houses. At the beginning of the Iron Age, some 2,000 years ago, people lived in small houses 10-12 metres long. The east side of the house was always reserved for the animals. If you look closely, you may spot partitions in two of the houses. These partitions are rarely visible today because they were dug deep into the ground. The photo also shows that the entrances were located in the middle of the houses. The field is greener where the people have dug holes for the walls and inside the houses for the poles that have supported the roof.

This field once housed a large Viking settlement. The centre of the picture shows vestiges of a Viking Age house with long curved walls. Other remnant houses are also visible in the cornfield, along with vestiges of pit houses.

Vestiges of Iron Age remnant houses enclosed by fencing. The photo also shows traces of an abandoned road from more recent times, which has run right through the field. Many of the remnant houses have relics of fences around them. Only about five remnant houses are visible on this picture – where the field is light and dry. It’s very likely that Iron Age houses have occupied the green parts of the field. But since the growth conditions are so good in this area, the corn has blocked our view of these houses.

Vestiges of small buried labour huts, called pit houses, from the Viking Age. All the round green spots in the field are relics of huts which have been dug a half to a full metre down into the ground. When these houses were no longer of any use, they were broken down and the hole was filled up with waste from the settlement. As a result, the corn is enjoying particularly good growing conditions in this area – even today, 1,000 years later.

Vestiges of a German trench from World War II. The Germans had extensive fortifications along the west coast of Jutland during the war. On the headland on this photo we see relics of a particularly impressive trench with a zigzag pattern. The zigzag shape prevents the enemy from standing at one end and shooting in through the trench.

Vestiges of remnant houses from the Early Iron Age, which stand side by side along what was once the village road. Also visible on this photo are relics of the extensions that have belonged to the farms. They are located behind the houses on the side facing away from the road. This find was named as one of the top ten finds of 2010 by the Danish Agency of Culture.

The nine areas in Denmark selected for the aerial archaeology project, which is scheduled to run until 2013.

Denmark’s past viewed from above

There’s a lot to learn about the past by studying the land from high above. See a series of stunning aerial archaeology photos here.

Charlotte Price Persson

Published 25 July 2012 - 07:00

Since 2009 archaeologists have been using small aircraft to map nine areas in Denmark that are of particular interest to archaeologists and historians.

The project is called 'The past as viewed from the sky – air archaeology in Denmark' and will initially run until 2013.

But what can aerial photos possibly tell us about the past?

Quite a lot, actually. When, for instance, the Vikings dug deep holes for the poles that bore their houses, it significantly altered the growth conditions on that particular piece of land.

An indication of how the contour and the size of the houses have changed over time. We see, for instance, a drop in the number of poles used for supporting the building. This is partly because the Vikings figured out that they could reinforce their houses by using curved walls. (Illustration from the book ‘Aerial photos of Denmark’ by Lis Helles Olesen, Henrik Dupont and Claus Dam)

This means that it’s still possible to spot differences in the way the grain grows on just the circle of land where the pole once stood.

This helps archaeologists determine the nature and the age of the buildings and the settlements.

“The objective of this project is to gain a clearer view of the ancient monuments in Denmark. I hope this will spark a greater interest in the past,” says archaeologist and project manager Lis Helles Olesen, who is also a curator at Holstebro Museum.

Sand is ideal for aerial archaeology

There are great differences in the kinds of soil layer that the archaeologists study from above. And that’s actually part of the reason why just these nine areas were selected: they represent all types of soil layer.

The objective of this project is to gain a clearer view of the ancient monuments in Denmark. I hope this will spark a greater interest in the past.

Lis Helles Olesen

“Sandy soil is the most suitable for studying archaeology from above,” says Olesen. “This is because growth differences in the soil layers are greater in sand than in other soil types, and that makes it easier to spot differences in the crops.”

Corn is better than grass, but grass is better than both potato and maize fields.

There may also be great differences in the appearance of the fields from year to year. During a very dry summer, archaeologists can make plenty of good, previously undiscovered finds by circling around the fields.

On a wet summer, however, the number of finds is much more limited. The corn simply grows too well, which means that growth differences in the grains are not sufficiently large for the archaeologists.

The houses change appearance throughout antiquity, and archaeologists now have a good overview of how the houses have looked in various periods of history.

Lis Helles Olesen

Other factors such as humidity and light can also influence how much or how little is visible on a given day.

For that reason, archaeologists sometimes keep coming across new finds simply by flying back and forth over the same piece of field at different times.

Ancient houses can be used to date findings

Of particular interest to the aerial archaeologists are remnant houses – houses that people once lived in. These houses enable archaeologists to determine with great precision which time period the find dates back to.

“The houses change appearance throughout antiquity, and archaeologists now have a good overview of how the houses have looked in various periods of history,” she says.

A pit house is a work hut from the Viking Age, which was used to e.g. forge and weave in.

Pit houses didn’t have room for much more than one man, and the roof was supported by two pillars on each side of the hut.

They were dug between a half and one meter down into the ground, which means they are relatively easy to see from the air even today.

”The most characteristic ones are the remnant houses with curved walls from the Viking Age [picture 5]. The design allowed for a minimum of poles inside the house to hold the roof. This opened up for a big open space in the middle of the house, in which large groups of people could be brought together.”

One of the most common finds in aerial archaeology is 'pit houses' – labour huts from the Viking period (picture 3). They were dug no more than a metre down into the ground. This makes it very clear to see that the grains grow differently in these areas.

Old photos scrutinised

However, 'The past as viewed from the sky – air archaeology in Denmark' covers more than the flights, which only take place in the summer.

The researchers also put old photos under systematic scrutiny – as with, for instance, photos taken during World War 2 to map the land.

Although the old photos are taken at a very long distance, they could well contain secrets from the past.

So far, the project has revealed more than 2,500 sites that may be of archaeological interest, and which could result in further funding for the project.

Olesen sincerely hopes the project can continue past its scheduled expiration in 2013.

Photo credits: Lis Helles Olesen and Esben Schlosser Mauritsen

Translated by: Dann Vinther