The Emsian stratigraphy of the southern Rhenish Massif can be divided into two lithological units: the older slates of the Hunsrück-Schiefer and the younger sandstones of the Singhofener Schichten.

In 1970, Wilhelm Stürmer, a chemical physicist and radiologist at Siemens, developed a new method to examine the Hunsrück slate fossils using medium energy X-rays of 25-40 keV.

He created high-resolution movies and stereoscopic images of unopened slates, which showed complex details of soft tissues that cannot be made visible with conventional methods.

More formally, the Hunsruck Slate is properly designated as a Konservat Lagerstätte due to the many fossils that exhibit preservation of soft tissues.

[5] Hunsrück is one of the few marine Devonian Lagerstätte having soft tissue preservation, and in many cases fossils are coated by a pyritic surface layer.

Preservation of soft tissues as fossils normally requires rapid burial in an anoxic (i.e., with little or no oxygen) sedimentary layer where the decomposition of the organic matter is significantly slowed.

There are also areas of the Hunsrück Slates where fossils are neither well preserved, nor pyritized, indicating that there also existed environments with shallow and fully oxygenated water.

The presence of corals and trilobites with well-developed eyes and the rarity of plant fossils from the central basin areas suggest a shallow-water environment.

[9] Agnathan jawless fishes are the most commonly preserved vertebrates, particularly the flattened Drepanaspis, notable for its upwards-facing mouth, and the streamlined Pteraspis.