In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene . It spans the time between 56 and 47.8 Ma , is preceded by the Thanetian Age (part of the Paleocene ) and is followed by the Eocene Lutetian Age. The Ypresian is consistent with the Lower Eocene (Early Eocene).
18-586: The San Jose Formation is an Early Eocene ( Wasatchian in the NALMA classification ) geologic formation in the San Juan Basin of New Mexico and Colorado . The San Jose Formation is mostly sandstone but with some mudstone beds. The formation was deposited by high-energy streams on a muddy floodplain that was the last preserved sedimentation episode in the San Juan Basin. Stream direction
36-664: Is the siltstone -dominated Tapicitos Member. The Cuba Mesa Member was deposited during subsidence in the basin center, while the later members were deposited during episodes of monoclinal folding along the Nacimiento Fault on the west escarpment of the Nacimiento Mountains . The mudstone beds of the San Jose Formation are locally rich in fossils. These include the Almagre and Largo faunas of
54-727: The Casamayoran South American Land Mammal Age and the Bumbanian and most of the Arshantan Asian Land Mammal Ages . It is also coeval with the upper Wangerripian and lowest Johannian regional stages of Australia and the Bulitian, Penutian, and Ulatisian regional stages of California . Ieper Group The Ieper Group ( Dutch : Ieper Groep ; French : Groupe d'Ypres ) is a group of rock strata in
72-756: The Global Stratotype Section and Point (GSSP) defined by the International Commission on Stratigraphy (ICS) for the Ypresian is set in the Dababiya section close to Luxor, Egypt, where the uppermost Tarawan Limestone , the Esna Formation and the lowermost Thebes Limestone define the Ypresian sequence. Several other proposals for the lithostratigraphic redefinition of the top of the Ypresian exist; among others
90-1220: The Punta Torcida Formation of the Austral or Magallanes Basin in Tierra del Fuego , the Azkorri Sandstone in the Gorrondatxe section of the North Pyrenean Foreland or Basque–Cantabrian Basin , the Agost section close to Alicante in the Agost Basin in the Betic Cordillera , and the Fortuna section north of Murcia in the Prebetic realm of the Betic Cordillera, all in Spain. Other proposed type sections for
108-775: The Tielt Formation , consisting of fine sand , is found in the subsurface of western and central Belgium and the Gentbrugge Formation , which comprises an alternation of clay, silt and fine sand, crops out in East and West Flanders. The Ieper Group lies stratigraphically on top of the Landen Group (upper Paleocene ) and below the Zenne Group (like the Ieper Group early Eocene in age). Unlike
126-732: The subsurface of northwest Belgium . The group is subdivided into three marine formations , all formed during the Ypresian , a single age of the geologic timescale (55.8 to 48.6 million years ago, the oldest age of the Eocene epoch ). Both age and group are named after the West Flemish town of Ypres , for which the Dutch name is "Ieper". In the original description of his newly introduced Ypresian stage Dumont (1850) did mention neither stratotype nor type locality. He simply referred to
144-438: The "collines d'Ypres" or Ieper Hills, as the area where the unit is best developed. However, it remains unclear what is meant by this term. The town of Ieper is situated in western Belgium, at the southern end of a small, NW-SE oriented depression (15 to 20 metres (49 to 66 ft) above mean sea level), surrounded from north to south by a series of low hills (between 25 and 45 metres (82 and 148 ft)). Dumont probably envisaged
162-860: The San Jose Formation. In 1967, the formation was divided (in ascending order) into the Cuba Mesa Member, Regina Member, Llaves Member, and Tapicitos Member. Early Eocene The Ypresian Age begins during the throes of the Paleocene–Eocene Thermal Maximum (PETM). The Fur Formation in Denmark , the Messel shales in Germany , the Oise amber of France and Cambay amber of India are of this age. The Eocene Okanagan Highlands are an uplands subtropical to temperate series of lakes from
180-661: The Ypresian-Lutetian boundary are located in France, Italy, Israel, Tunisia, Morocco, Cuba and Mexico. The Ieper Group was redefined by Steurbaut in 2006, and is since 2017 subdivided into five formations by the National Commission for the Stratigraphy of Belgium, from youngest to oldest: The Kortrijk Formation predominantly consists of marine clay . It occurs in the west and north of Belgium,
198-612: The Ypresian. The Ypresian is additionally marked by another warming event called the Early Eocene Climatic Optimum (EECO). The EECO is the longest sustained warming event in the Cenozoic record, lasting about 2–3 million years between 53 and 50 Ma. The interval is characterized by low oxygen-18 isotopes, high levels of atmospheric p CO 2 , and low meridional thermal gradients. Biodiversity has been reported to have been significantly impacted by
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#1732771882762216-464: The badlands north of Regina, New Mexico and spent about seven weeks collecting fishes, reptiles, and what was then the oldest known mammal fossils in North America. He also collected the fossil of a giant flightless bird. Cope later wrote his father that this was "the most important find in geology I have ever made". In 1948, G.G. Simpson visited the same area and assigned the fossil beds to
234-652: The conditions prevalent during the EECO. For instance, there were biotic turnovers among marine producers such as calcareous nannofossils among others etc. The Ypresian Stage was introduced in scientific literature by Belgian geologist André Hubert Dumont in 1850. The Ypresian is named after the Flemish city of Ypres in Belgium (spelled Ieper in Dutch). The definitions of the original stage were totally different from
252-595: The early Eocene. Among others, the following fossils have been reported from the formation: In late 1874, Edward Drinker Cope was a member of the Wheeler Survey but ignored orders from Wheeler to proceed north from the Chama River to Colorado . Instead, he headed south to explore the area north of the San Pedro Mountains , where fossils had been reported. He found early Eocene fossils in
270-499: The elevated zones a few km north and east of Ieper (St.-Jan, Zillebeke, etc.), where clay beds have been quarried for brick and tile making for quite a long time. A new stratotype for the Lutetian was proposed by Blondeau (1981) about 50 kilometres (31 mi) north of Paris. The neostratotype is located on the right bank of the river Oise at St. Leu d'Esserent and the large quarry at St. Vaast-les-Mello ( Oise ). Since 2003,
288-650: The modern ones. The Ypresian shares its name with the Belgian Ieper Group (French: Groupe d'Ypres ), which has an Ypresian age. The base of the Ypresian Stage is defined at a strong negative anomaly in δ C values at the PETM . The official reference profile ( GSSP ) for the base of the Ypresian is the Dababiya profile near the Egyptian city of Luxor . Its original type section was located in
306-710: The vicinity of Ieper. The top of the Ypresian (the base of the Lutetian) is identified by the first appearance of the foraminifera genus Hantkenina in the fossil record. The Ypresian Stage overlaps the upper Neustrian and most of the Grauvian European Land Mammal Mega Zones (it spans the Mammal Paleogene zones 7 through 10. ), the Wasatchian and lower and middle Bridgerian North American Land Mammal Ages ,
324-487: Was from the northwest, north, and east towards the south. The basal Cuba Mesa Member is found throughout the depositional basin and is a coarse-grained sheet sandstone. The Regina Member is floodplain mudstone and disconnected sheet sandstone that intertongues with the sandstone-dominated Ditch Canyon Member in the northwestern part of the basin and the Llaves Member on the east side of the basin. The uppermost member
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