The present work is about the phenomenon Dark Earth, in the German-speaking area more well known as "schwarze Schicht". The term Dark Earth describes a dark, homogenous stratigraphical unit, which is often found in the course of archaeological excavations in Europe in urban or urban-like areas. It mostly is poorly stratified and characterized as a dark coloured layer, with a general uniformity and an absence of findings. A unit like this often lies in between the well-stratified roman and medieval occupation layers. In the present work the history of researching Dark Earth will be presented, along with some natural scientific methods, which can be used to analyse the dark earth units. Furthermore explanation models concerning the formation of Dark Earth are introduced and in the end different examples will be discussed. The purpose of the present work is to give a diversified overview of the topic and, if possible, draw a conclusion from the different interpretations and explanations concerning Dark Earth.