Fur Formation
Encyclopedia
Essentially the Fur Formation is defined as a clayey diatomite with a lage number of volcanic ash layers.
The Fur Formation is a marine geological formation of Ypresian
(Lower Eocene Epoch, c. 56-54,5 Ma) age which crops out in the Limfjord region of Denmark
from Silstrup via Mors and Fur (island)
to Ertebølle, and can be seen in many cliffs and quarries in the area. The Diatomite Cliffs (Moler) is on the Danish list of tentative candidates for World Heritage and may become a world Heritage site. The Heritage Agency of DenmarkThe Heritage Agency of Denmark.
The Fur Formation is a diatomitic sediment approximately 60 meters thick consisting of diatom
s and clay minerals. In Danish literature the formation has informally been referred to as the Moler in English (Mo-clay). The mo-clay is a diatomite with 2/3 opal tests of diatoms, 1/3 clay and volcanic dust and with few limestone
horizons (‘cementstones’) and exceptionally complete fossil preservation.
It is known for its abundant fossil
fish, insects, reptiles, birds and plants. The Fur Formation was deposited just above the Palaeocene-Eocene
boundary, about 55 million years ago, and its tropical or sub-tropical flora indicate that the climate after the Paleocene-Eocene Thermal Maximum
was moderately warm (approximately 4-8 degrees warmer than today).
The Fur Formation is divided into two members:
The lower Knudeklint Member was named for a location on the island of Fur
. The upper Silstrup Member was named for a location on Thy
.
Glacial activity has moved and folded all exposed mo-clay in a complicated pattern which permits very precise mapping of movements of glaciers in a late part of last ice age, and has, due to the ash layers, created an extraordinary pedagogical case for studding tectonics.
Birds
The earliest Tertiary fauna of any diversity, over 30 species, some near complete and preserved in 3-D some excellent bird-fossils, even with feathers and chromatine. Most are earliest known representatives of their ‘orders’, and all are terrestrial birds.
Reptiles
Turtles and snakes: Large leatherback (Eosphargis
), near complete, earliest of family; a 10 cm, complete chelonid has soft tissue and some horn plates preserved.
Fishes
Large teleostean fauna, oceanic, possibly including earliest truly deep water fish, a ‘whale-fish’; earliest members of many living families and Tertiary diversity preserved as complete skeletons; some rare and sensational large and complete specimens (two ‘bony tongues’, one tarpon.
Insects
Huge fauna from land, over 200 species, earliest Tertiary diversity known, many are oldest of their families; many with colour spots and eye lenses, some extraordinary preservation with stridulation (sound) apparatus in grasshoppers, and apparently migratory moth mass mortality.
Crustacea
Extraordinary cirripeds (barnacles), and the only fossil shrimps from Denmark.
Land plants
Some members of the ‘Arcto-Tertiary flora’; some with cuticle preservation and some flowers preserved. Large silicified trunks (up to 9 m) of redwood, and some very soft wood preserved. Some trunks with mussels and barnacles attached. Many seeds and fruits.
Diatoms
Great diversity of unicellular, marine algae with siliceous (opal) tests, 130 species.
of predominantly basalt
ic composition have been found within the Mo-clay of the Fur Formation. 179 of the most prominent ash layers have been numbered. Comparison with volcanic ash layers in oil well
s in the North Sea
indicates that the Mo-clay is coeval with the Sele Formation and Balder Formation in the North Sea. The ash layers have also been found at other sites in Denmark
, England
, Austria
and the Bay of Biscay
.
The total eruption volume of this series have been calculated as 21,000 km3, which occurred in 600,000 years. The most powerful single eruption of this series took place 54.0 million years ago (Ma) and ejected ca. 1,200 km3 of ash material, which makes it one of the largest basaltic pyroclastic eruptions in geological history.
Image:Fur geological layers.jpg|Image showing the distinct geological layers.
Image:Fur layers 2.jpg|An inland location.
Image:Fur cliffs.jpg|These cliffs of Fur have been a rich source of fossils.
Image:Fossil bird head.jpg|Bird fossil with preserved feathers from Fur, at the Geological Museum, Copenhagen
The Fur Formation is a marine geological formation of Ypresian
Ypresian
In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between and , is preceded by the Thanetian age and is followed by the Eocene Lutetian age....
(Lower Eocene Epoch, c. 56-54,5 Ma) age which crops out in the Limfjord region of Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
from Silstrup via Mors and Fur (island)
Fur (island)
Fur is a small Danish island in the Limfjord at the northern tip of the Salling peninsula. Fur has under 900 inhabitants. The island covers an area of 22 km². It is located at ....
to Ertebølle, and can be seen in many cliffs and quarries in the area. The Diatomite Cliffs (Moler) is on the Danish list of tentative candidates for World Heritage and may become a world Heritage site. The Heritage Agency of DenmarkThe Heritage Agency of Denmark.
The Fur Formation is a diatomitic sediment approximately 60 meters thick consisting of diatom
Diatom
Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons , fans , zigzags , or stellate colonies . Diatoms are producers within the food chain...
s and clay minerals. In Danish literature the formation has informally been referred to as the Moler in English (Mo-clay). The mo-clay is a diatomite with 2/3 opal tests of diatoms, 1/3 clay and volcanic dust and with few limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
horizons (‘cementstones’) and exceptionally complete fossil preservation.
It is known for its abundant fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
fish, insects, reptiles, birds and plants. The Fur Formation was deposited just above the Palaeocene-Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
boundary, about 55 million years ago, and its tropical or sub-tropical flora indicate that the climate after the Paleocene-Eocene Thermal Maximum
Paleocene-Eocene Thermal Maximum
The most extreme change in Earth surface conditions during the Cenozoic Era began at the temporal boundary between the Paleocene and Eocene epochs . This event, the Paleocene–Eocene Thermal Maximum , was associated with rapid global...
was moderately warm (approximately 4-8 degrees warmer than today).
The Fur Formation is divided into two members:
The lower Knudeklint Member was named for a location on the island of Fur
Fur (island)
Fur is a small Danish island in the Limfjord at the northern tip of the Salling peninsula. Fur has under 900 inhabitants. The island covers an area of 22 km². It is located at ....
. The upper Silstrup Member was named for a location on Thy
Thy (district)
Thy is a traditional district in northwestern Jutland, Denmark. It is situated north of the Limfjord, facing the North Sea and Skagerrak, and has a population of around 50,000. The main towns of Thy are Thisted, Hanstholm and Hurup....
.
Glacial activity has moved and folded all exposed mo-clay in a complicated pattern which permits very precise mapping of movements of glaciers in a late part of last ice age, and has, due to the ash layers, created an extraordinary pedagogical case for studding tectonics.
Fossils
Fossils of great diversity and unique preservation (only 10 my. after the ‘great extinction’ of dinosaurs, ammonites etc.) Most unusual, if not unique, diversity of life from both ocean and land with extremely good preservation of details rarely seen, therefore very reliable reconstruction of palaeobiology. By far most of the important ‘Danekræ’ fossils since 1990 have been found in the ‘Mo-clay area’.Birds
The earliest Tertiary fauna of any diversity, over 30 species, some near complete and preserved in 3-D some excellent bird-fossils, even with feathers and chromatine. Most are earliest known representatives of their ‘orders’, and all are terrestrial birds.
Reptiles
Turtles and snakes: Large leatherback (Eosphargis
Eosphargis
Eosphargis is an extinct genus of sea turtle from the Eocene of Africa, Europe, and North America. It was first named by Richard Lydekker in 1889, and contains one species, E. gigas. The species is also known as Anglocetus beatsoni....
), near complete, earliest of family; a 10 cm, complete chelonid has soft tissue and some horn plates preserved.
Fishes
Large teleostean fauna, oceanic, possibly including earliest truly deep water fish, a ‘whale-fish’; earliest members of many living families and Tertiary diversity preserved as complete skeletons; some rare and sensational large and complete specimens (two ‘bony tongues’, one tarpon.
Insects
Huge fauna from land, over 200 species, earliest Tertiary diversity known, many are oldest of their families; many with colour spots and eye lenses, some extraordinary preservation with stridulation (sound) apparatus in grasshoppers, and apparently migratory moth mass mortality.
Crustacea
Extraordinary cirripeds (barnacles), and the only fossil shrimps from Denmark.
Land plants
Some members of the ‘Arcto-Tertiary flora’; some with cuticle preservation and some flowers preserved. Large silicified trunks (up to 9 m) of redwood, and some very soft wood preserved. Some trunks with mussels and barnacles attached. Many seeds and fruits.
Diatoms
Great diversity of unicellular, marine algae with siliceous (opal) tests, 130 species.
Ash layers
More than 200 layers of volcanic ashVolcanic ash
Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...
of predominantly basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
ic composition have been found within the Mo-clay of the Fur Formation. 179 of the most prominent ash layers have been numbered. Comparison with volcanic ash layers in oil well
Oil well
An oil well is a general term for any boring through the earth's surface that is designed to find and acquire petroleum oil hydrocarbons. Usually some natural gas is produced along with the oil. A well that is designed to produce mainly or only gas may be termed a gas well.-History:The earliest...
s in the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
indicates that the Mo-clay is coeval with the Sele Formation and Balder Formation in the North Sea. The ash layers have also been found at other sites in Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
, Austria
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
and the Bay of Biscay
Bay of Biscay
The Bay of Biscay is a gulf of the northeast Atlantic Ocean located south of the Celtic Sea. It lies along the western coast of France from Brest south to the Spanish border, and the northern coast of Spain west to Cape Ortegal, and is named in English after the province of Biscay, in the Spanish...
.
The total eruption volume of this series have been calculated as 21,000 km3, which occurred in 600,000 years. The most powerful single eruption of this series took place 54.0 million years ago (Ma) and ejected ca. 1,200 km3 of ash material, which makes it one of the largest basaltic pyroclastic eruptions in geological history.
Image:Fur geological layers.jpg|Image showing the distinct geological layers.
Image:Fur layers 2.jpg|An inland location.
Image:Fur cliffs.jpg|These cliffs of Fur have been a rich source of fossils.
Image:Fossil bird head.jpg|Bird fossil with preserved feathers from Fur, at the Geological Museum, Copenhagen