Hunsrück Slate
Encyclopedia
The Hunsrück Slate is a Lower Devonian
lithostratigraphic
unit, a type of rock strata
, in the German
regions of the Hunsrück
and Taunus
. It is a lagerstätte
famous for exceptional preservation of a highly diverse fossil
fauna assemblage.
units: the older slate
s of the Hunsrück-Schiefer and the younger sandstone
s of the Singhofener Schichten. Stratigraphically below the Hunsrück Slates is the (older) Taunus quartzite. All these metasedimentary rocks were originally deposited in the marine
Rhenohercynian Basin, a back-arc basin
south of the paleocontinent of Laurussia.
The Hunsrück Slate roughly comprises the Sauerthal-Schichten, Bornich-Schichten and Kaub-Schichten. These are 408–400 Mya old, making them part of the Latest Pragian to Early Emsian stages of the Devonian.
over several centuries. Archaeological finds in West Germany show that the slate was used in Roman times. The first documented case of mining in this area dates from the 14th century. The production continued with the Industrial Revolution
at the end of the 1700s, but in 1846-49, the industry fell into crisis, resulting in poverty and misery in the mining areas.
The economic upturn after the Franco-Prussian War
of 1870-71 resulted in a renewed increase in slate production, where companies used more extensive pits. Production continued until the 1960s, when the competition from cheaper synthetic or imported slate resulted in production decline. Only a single pit in the Bundenbach
region was worked in the 1990s. Since 1999, slate imports from Spain
, Portugal
, Argentina
and China
caused the abandonment of local mining.
Mining of Hunsrück slate was important for the discovery of fossils. Although not rare, fossils can only be found through extensive mining of slate. Many of the fine fossils exhibited in museums today were originally found by the slate miners. The first scientific publication on these fossils comes from Ferdinand von Roemer
(1862), who described starfish and crinoid
fossils from Bundenbach. German paleontologists such as R. Opitz, F. Broili, R. Judge, and W. M. Lehmann studied many fossils between 1920 and 1959. Lehmann's death in 1959 and the decline of the slate industry caused a decline in fossil research.
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. In the 1990s, Christoph Bartels and Günther Brassel have continued this work.
located mostly south of the River Mosel and west of the Rhine in western Germany
. The biota
of the Hunsrück Slate are commonly called "Bundenbach fossils" after the nearby German community of Bundenbach. More formally, the Hunsruck Slate is properly designated as a Konservat Lagerstätte
due to the many fossils that exhibit preservation of soft tissues.
(i.e., with little or no oxygen) sedimentary layer where the decomposition of the organic matter is significantly slowed. The pyritization found in Bundenbach fossils facilitated preservation and enhanced the inherent beauty of the fossils.
Pyritization is rare in the fossil record, and is believed to require not only rapid burial, but burial in sediments low in organic matter, but high in concentrations of sulfur and iron. Such pyritization is also prevalent in the lower Cambrian fossils from the Maotianshan shales
of Chengjiang, China, the oldest Konservat Lagerstätte of Cambrian
time.
The best localities for exceptionally preserved fossils are in the communities of Bundenbach and Gemünden. The slates were widely quarried in the past, mainly for roofing tiles from small pits, of which over 600 are known. Today, only a single quarry remains open in the main fossiliferous region of Bundenbach. 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.
s with well-developed eyes and the rarity of plant fossils from the central basin areas suggest a shallow-water environment. Other animal fossils include sponges
, corals, brachiopods, cephalopods, cnidarians, gastropods, and worm trace fossils. Trilobites and echinoderms are relatively abundant in some horizons. Crinoids and starfish are the predominant representatives of the echinoderms, although holothurians (sea cucumbers) are also represented. More than 60 species of crinoids are described from the Hunsrück Slate. Both placoderm armoured fish and agnatha
jawless fish have been discovered.
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
lithostratigraphic
Lithostratigraphy
Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology...
unit, a type of rock strata
Stratum
In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...
, in the German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
regions of the Hunsrück
Hunsrück
The Hunsrück is a low mountain range in Rhineland-Palatinate, Germany. It is bounded by the river valleys of the Moselle , the Nahe , and the Rhine . The Hunsrück is continued by the Taunus mountains on the eastern side of the Rhine. In the north behind the Moselle it is continued by the Eifel...
and Taunus
Taunus
The Taunus is a low mountain range in Hesse, Germany that composes part of the Rhenish Slate Mountains. It is bounded by the river valleys of Rhine, Main and Lahn. On the opposite side of the Rhine, the mountains are continued by the Hunsrück...
. It is a lagerstätte
Lagerstätte
A Lagerstätte is a sedimentary deposit that exhibits extraordinary fossil richness or completeness.Palaeontologists distinguish two kinds....
famous for exceptional preservation of a highly diverse fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
fauna assemblage.
Geology
The Emsian stratigraphy of the southern Rhenish Massif can be divided into two lithologicalLithology
The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples or with low magnification microscopy, such as colour, texture, grain size, or composition. It may be either a detailed description of these characteristics or be a summary of...
units: the older slate
Slate
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. The result is a foliated rock in which the foliation may not correspond to the original sedimentary layering...
s of the Hunsrück-Schiefer and the younger sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
s of the Singhofener Schichten. Stratigraphically below the Hunsrück Slates is the (older) Taunus quartzite. All these metasedimentary rocks were originally deposited in the marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
Rhenohercynian Basin, a back-arc basin
Back-arc basin
Back-arc basins are geologic features, submarine basins associated with island arcs and subduction zones.They are found at some convergent plate boundaries, presently concentrated in the Western Pacific ocean. Most of them result from tensional forces caused by oceanic trench rollback and the...
south of the paleocontinent of Laurussia.
The Hunsrück Slate roughly comprises the Sauerthal-Schichten, Bornich-Schichten and Kaub-Schichten. These are 408–400 Mya old, making them part of the Latest Pragian to Early Emsian stages of the Devonian.
History of mining
The Hunsrück slate was a source for Rhenish slateSlate
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. The result is a foliated rock in which the foliation may not correspond to the original sedimentary layering...
over several centuries. Archaeological finds in West Germany show that the slate was used in Roman times. The first documented case of mining in this area dates from the 14th century. The production continued with the Industrial Revolution
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...
at the end of the 1700s, but in 1846-49, the industry fell into crisis, resulting in poverty and misery in the mining areas.
The economic upturn after the Franco-Prussian War
Franco-Prussian War
The Franco-Prussian War or Franco-German War, often referred to in France as the 1870 War was a conflict between the Second French Empire and the Kingdom of Prussia. Prussia was aided by the North German Confederation, of which it was a member, and the South German states of Baden, Württemberg and...
of 1870-71 resulted in a renewed increase in slate production, where companies used more extensive pits. Production continued until the 1960s, when the competition from cheaper synthetic or imported slate resulted in production decline. Only a single pit in the Bundenbach
Bundenbach
Bundenbach is an Ortsgemeinde – a municipality belonging to a Verbandsgemeinde, a kind of collective municipality – in the Birkenfeld district in Rhineland-Palatinate, Germany...
region was worked in the 1990s. Since 1999, slate imports from Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
, Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
and China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
caused the abandonment of local mining.
Mining of Hunsrück slate was important for the discovery of fossils. Although not rare, fossils can only be found through extensive mining of slate. Many of the fine fossils exhibited in museums today were originally found by the slate miners. The first scientific publication on these fossils comes from Ferdinand von Roemer
Ferdinand von Roemer
Carl Ferdinand von Roemer , German geologist, had originally been educated for the legal profession at Göttingen, but became interested in geology, and abandoning law in 1840, studied science at the University of Berlin, where he graduated Ph.D...
(1862), who described starfish and crinoid
Crinoid
Crinoids are marine animals that make up the class Crinoidea of the echinoderms . Crinoidea comes from the Greek word krinon, "a lily", and eidos, "form". They live both in shallow water and in depths as great as 6,000 meters. Sea lilies refer to the crinoids which, in their adult form, are...
fossils from Bundenbach. German paleontologists such as R. Opitz, F. Broili, R. Judge, and W. M. Lehmann studied many fossils between 1920 and 1959. Lehmann's death in 1959 and the decline of the slate industry caused a decline in fossil research.
In 1970, Wilhelm Stürmer, a chemical physicist and radiologist at Siemens
Siemens
Siemens may refer toSiemens, a German family name carried by generations of telecommunications industrialists, including:* Werner von Siemens , inventor, founder of Siemens AG...
, developed a new method to examine the Hunsrück slate fossils using medium energy X-rays of 25-40 keV
Kev
Kev can refer to:*Kev Hawkins, a fictional character.*Kevin, a given name occasionally shortened to "Kev".*Kiloelectronvolt, a unit of energy who symbol is "KeV".* Krefelder Eislauf-VereinKEV can refer to:...
. 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. In the 1990s, Christoph Bartels and Günther Brassel have continued this work.
Paleontology
The various fossil localities are quarriesQuarry
A quarry is a type of open-pit mine from which rock or minerals are extracted. Quarries are generally used for extracting building materials, such as dimension stone, construction aggregate, riprap, sand, and gravel. They are often collocated with concrete and asphalt plants due to the requirement...
located mostly south of the River Mosel and west of the Rhine in western Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
. The biota
Biota (ecology)
Biota are the total collection of organisms of a geographic region or a time period, from local geographic scales and instantaneous temporal scales all the way up to whole-planet and whole-timescale spatiotemporal scales. The biota of the Earth lives in the biosphere.-See...
of the Hunsrück Slate are commonly called "Bundenbach fossils" after the nearby German community of Bundenbach. More formally, the Hunsruck Slate is properly designated as a Konservat Lagerstätte
Lagerstätte
A Lagerstätte is a sedimentary deposit that exhibits extraordinary fossil richness or completeness.Palaeontologists distinguish two kinds....
due to the many fossils that exhibit preservation of soft tissues.
Preservation and taphonomy
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 anoxicAnoxic sea water
Anoxic waters are areas of sea water or fresh water that are depleted of dissolved oxygen. This condition is generally found in areas that have restricted water exchange....
(i.e., with little or no oxygen) sedimentary layer where the decomposition of the organic matter is significantly slowed. The pyritization found in Bundenbach fossils facilitated preservation and enhanced the inherent beauty of the fossils.
Pyritization is rare in the fossil record, and is believed to require not only rapid burial, but burial in sediments low in organic matter, but high in concentrations of sulfur and iron. Such pyritization is also prevalent in the lower Cambrian fossils from the Maotianshan shales
Maotianshan shales
The Maotianshan Shales are a series of lower Cambrian deposits in the Chiungchussu formation, famous for their Konservat Lagerstätten, or high number of fossils preserved in place...
of Chengjiang, China, the oldest Konservat Lagerstätte of Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
time.
The best localities for exceptionally preserved fossils are in the communities of Bundenbach and Gemünden. The slates were widely quarried in the past, mainly for roofing tiles from small pits, of which over 600 are known. Today, only a single quarry remains open in the main fossiliferous region of Bundenbach. 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.
Diversity of fauna
More than 260 animal species have been described from the Hunsrück Slate. The deposits occur in a strip some 15 km wide and 150 km long running from northwest to southeast. In the main depositional basins of Kaub, Bundenbach, and Gemünden, echinoderms are concentrated in the southwestern area around Bundenbach, with brachiopods predominating in the northeast. The presence of corals and trilobiteTrilobite
Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period , and they flourished throughout the lower Paleozoic era before...
s with well-developed eyes and the rarity of plant fossils from the central basin areas suggest a shallow-water environment. Other animal fossils include sponges
Sea sponge
Sponges are animals of the phylum Porifera . Their bodies consist of jelly-like mesohyl sandwiched between two thin layers of cells. While all animals have unspecialized cells that can transform into specialized cells, sponges are unique in having some specialized cells, but can also have...
, corals, brachiopods, cephalopods, cnidarians, gastropods, and worm trace fossils. Trilobites and echinoderms are relatively abundant in some horizons. Crinoids and starfish are the predominant representatives of the echinoderms, although holothurians (sea cucumbers) are also represented. More than 60 species of crinoids are described from the Hunsrück Slate. Both placoderm armoured fish and agnatha
Agnatha
Agnatha is a superclass of jawless fish in the phylum Chordata, subphylum Vertebrata. The group excludes all vertebrates with jaws, known as gnathostomes....
jawless fish have been discovered.