How archaeologists identify excavation sites

Methods of archeology

Archaeobotany

Wherever people have settlements, have prepared food or stored food, traces can still be found today in the form of plant residues.

These can be preserved for a long time by charring, drying or moist storage in the absence of air. However: The plant remains are usually so small that they can easily be overlooked in conventional archaeological excavations.

Archaeobotanists recover plant remains that have been preserved, for example, through drought, ice, salts or even just as prints on vessels. In addition to larger parts of vegetation such as fruits, seeds or wood residues, residues of pollen and spores also provide valuable information about the plant world of bygone times.

From this, the eating habits and cultivation methods of the people in the respective settlement can be reconstructed. Archaeobotanical investigations are now standard in archaeological excavations.

Aerial archeology

Many structures can be recognized from above, but nothing is noticeable close to the ground. Using satellite images and images from airplanes, aerial archaeologists can even discover completely buried, former settlements. For example, the vegetation grows differently over the remains of a wall than around it.

Sometimes it is enough to look from an elevation of a grain field, and the different heights of the plants reveal different soil compositions, which indicate the earlier development of the area.

If you look at a snow-covered landscape from the air, you can also recognize monuments in the ground by means of snow drifts.

Often it is only through the analysis of aerial photographs that it becomes clear whether an excavation is worthwhile. If, for example, a buried road that can be seen from the air leads to a hill, then it can be assumed that the hill had an earlier meaning, for example as a burial chamber or house.

Dendrochronology

The so-called dendrochronology makes use of the fact that a typical pattern develops in tree trunks over the years. Every year a new ring is created in a tree trunk, the so-called annual ring. Years when the tree grew well can be seen in the trunk as wider rings.

So trees that grew in the same area develop similar ring patterns. The pattern of a single tree covers a period of 50 years, for example.

This time span can be extended by looking for overlaps with ring sequences from other trees and thus gradually bringing the patterns of increasingly older wood samples into the correct chronological order.

If this dendrochronological pattern is available for a specific region, for example Scandinavia, each wood sample can be compared with it and consequently assigned to a specific time.

Archaeometallurgy

Our ancestors worked metals in various ways. They forged, cast, annealed or used other working techniques. The hammering and glowing leaves typical traces in the core structure of the metals that can be found under the microscope.

If these traces are similar on samples from widely spaced sites, one can assume that the pieces come from the same region or even from the same workshop. And of course, conclusions can also be drawn about the quality and the way in which individual workpieces were created.

In short: Archaeometallurgy tells us a lot about the art of metalworking and the trade relations of early cultures.

Preservation of wood

Archaeological wood is full of holes like Swiss cheese. While the cell walls form a thick layer in fresh wood, in wood that has been stored in the wet for thousands of years they are severely hollowed out by bacterial damage.

The cavities are filled with water that evaporates as it dries. The result: the cell walls collapse, the wood shrinks and loses its original shape.

In order to preserve archaeological wood, it has to be treated in a lengthy process in a soaking bath in the wet wood laboratory. Today, water-soluble polyethylene glycol (PEG) is used for this. The artificial wax penetrates the water-filled wood and gradually fills the cavities.

During the subsequent drying process, the new stabilizing agent in the wood ensures that the cell walls do not collapse. The grain size of the PEG molecules, the concentration and the temperature of the soaking bath must be tailored to each individual type of wood.

Underwater archeology

Treasure diving has a long tradition. The Greek historian Herodotus (485 to 425 BC) refers to the Persian king Xerxes, who gave the order as early as 480 BC to dive for the treasures of the Persian fleet that sank off the Magnesia peninsula.

Underwater archeology, on the other hand, is a comparatively young discipline. It was only with the use of modern diving technology that it was possible to search for traces of sunken worlds on the bottom of lakes, rivers and seas.

As early as 1854, the Swiss archaeologist Karl Adolph von Morlot had a diving cap made that was connected to a hose with a kind of bicycle pump and supplied the diver with air.

With this, Morlot had the first diving excavations carried out in Lake Geneva. Almost 100 years later, the French diving pioneer Jacques-Yves Cousteau also revolutionized underwater archeology.

In the 1950s, he and archaeologists undertook numerous dives from the research vessel Calypso to sunken wrecks. In 1952, for example, Cousteau discovered a very well-preserved merchant ship from the ancient world off the coast of Marseilles.

In the meantime, underwater archeology, in which diving robots are increasingly used, has become an integral part of archaeological research. Because under water, some finds - once they have been covered with sediment - are much better preserved, as they were exposed to significantly less disturbance than on land.

Experimental archeology

Some of the finds are a mystery to archaeologists. What did the equipment or structure originally look like, what was it used for and how were the parts made? Sometimes only the experiment provides a plausible explanation.

Experimental archeology tries to reconstruct the everyday life of our ancestors. Trees are felled with replicated stone axes or dugouts are built with stone axes.

Bread is baked, millet porridge boiled, forged, spun or made fire - and all of this with the tools and materials originally available.

Experimental archeology has a long tradition, especially in the Anglo-Saxon and Scandinavian countries. As early as 1879, the Danish amateur archaeologist Frederik Sehested built a log house with Stone Age tools and thus proved that wood could be processed professionally without metal tools.

The most famous representative of experimental archeology is probably the Norwegian Thor Heyerdahl. In 1947 he undertook his world-famous Kon-Tiki expedition, on which he sailed from South America across the Pacific to Polynesia on a self-made raft made of balsa wood.

Heyerdahl wanted to prove that the islands in the Pacific were settled from South America. The 1951 documentary about the expedition even received an Oscar.