Why are Bog Bodies Preserved for Thousands of Years?

The Tollund Man's bog had some very special qualities. Extra large picture. More illustrations. © Niels Bach

Peat moss. Big picture

The reason why the bogs of Jutland are acidiferous is to be found in the strong wind from the North Sea which carries salt. The salt makes it possible for a special plant to dominate the bog. The name of the plant is peat bog, and one of its characteristics is that it gives off acid to the water. When peat moss rots more acid is created - this acid is called humic acid (alsom known as "bog acid"). All things considered the bog water reaches almost the same degree of sourness as vinegar. Some bogs are so acidiferous that the calvareous bones of the bog bodies have corroded into nothing, leaving only the skin and hair.

On the other hand, in areas located far from saltwater oceans the bog water is often calvareous. The bacteria have perfect living conditions and the bodies which are placed in these bogs will loose all their soft parts within a short period of time and will be completely skeletonized.

Lindow Man was discovered in an acidiferous bog. Big picture

It was later discovered that if a bog body is to be preserved, it must be placed in the bog at a time of year when the bog water is cold, that means 4 degrees celcius or less. Otherwise you risk that the soft parts of the body will start to decompose before the preserving humic acid has insinuated the body completely. The reason why 4 degrees is the critical temperature, is the fact that bacteria grow best in temperatures higher than that. That is also why the temperature in a refrigerator should not be higher than 4 degrees.

Bogs located in the eastern part of Denmark are calvareous which means that if the Tollund Man had been placed in a bog on Zealand we would only have discovered his skeleton. The people who placed the Tollund Man in the bog probably didn't know that he would be preserved for posterity.

In 1984 in England close to Manchester a well-preserved bog body was discovered - they named him Lindow Man. Here he is right after he was discovered and before he was preserved.