Source: http://www.geschiedenisleraar.info/blog/?tag=veenlijken

Also know as: peatcorps or moorcorps.

bog body is a human cadaver that has been naturally mummified in a peat bog. Unlike most ancient human remains, bog bodies have retained their skin due to the unusual conditions of the surrounding area. These conditions include highly-acidic water, low temperature, and a lack of oxygen, and combine to preserve but severely tan their skin. While the skin is well-preserved, the bones are generally not, due to the acid in the peat having dissolved the calcium phosphate of bone.