Hallo Thomas
ich bin mal zu den Quellen der lithostratographischen Terminologie vorgedrungen - da diese allesamt in England liegen, erscheint es mir natürlich, einige (der sehr vielen) Definitionen eben auch in Englisch zu senden. (Einige Begriffe habe ich in Klammern übersetzt)
"Abstract"The term
Malm, designated by Oppel (1856), comes from an English term used by quarrymen and makes reference to the
friable limestone (bröckeliger Kalkstein) that was used as a mill stone.
Dogger, adopted by by C.F. Naumann (1854), is also a quarryman’s term; it refers to the
rounded sandstone concretions found in the English series in Yorkshire.
The term
Lias is widely used, sometimes as a system name; thus, we talk about the Liassic and the Jurassic. The term was created by W. Smith (1799), in Somerset (England), and has its etymological origin in the word for layer. Its origin is also probably its use by quarrymen. It is a harder stratum placed between loams.
All these terms were created in England, one of the first places in which the Jurassic was studied and where it is well-developed
Quelle: REGUANT, S., 2009; Geology as a “local” science; Contributions to Science, 5(1): 41–51 (2009); Institut d’Estudis Catalans, Barcelona ; ISSN: 1575-63
MalmMalm ist ein historischer Begriff, der für die Serie des Oberen Jura noch häufig gebraucht wird. Die Bezeichnung stammt von Gesteinen, die in der Umgebung von Oxford in England zu Tage treten. Er ist heute provisorisch für eine lithostratigraphische Gruppe im Oberjura Norddeutschlands reserviert (Norddeutscher Malm). (Wiki)
Malm is a chalky-clayey soil or rock (kreidig-lehmiger Boden oder Gestein), in part equivalent to the term marl (Mergel) and used looseley of other impure calcareous rocks.
Malm is an obsolete old name for the Upper Jurassic.
(WHITTEN, D.G.A., BROOKS, J.R.V., 1972; Dictionary of geology)
Malm, der, nur im gemeinen Leben einiger Gegenden, ein zerriebener, zu Pulver gemachter, gemahlener Körper, Staub, Graus, Gries etc. Im Schwedischen heißt Malm der Sand. Daher zermalmen.
(Quelle: KRÜNITZ, 1773-1858; Oeconomische Encyclopädie, Band 83
DOGGERDogger is a large spherical oblately spherical calcareous concretion. The term is usually applied to large masses, as opposed to the smaller nodules. No formal size limits have been proposed; it is here suggested that the term dogger should be applied to concretionary masses with a diameter greater than 256 mm. (Quelle: WHITTEN, D.G.A., BROOKS, J.R.V., 1972; Dictionary of geology)
Eine sehr detaillierte Beschreibung des Dogger unter: Dogger - The BGS Lexicon of Named Rock Units — Result Details . Der Gesamttext ist zu umfangreich und würde den Rahmen des Forums sprengen.
Und ganz allgemein zu Dogger:
http://www.bgs.ac.uk/Lexicon/lexicon.cfm?pub=DGRLIASLias is a name, which dates back to some of the oldest works of geology, signifying the earliest of the three sub-divisions of the Jurassic Period; the subsequent ones being the ‘dogger’ and the ‘malm’.
William Smith’s (and the world’s) first geology map of 1799 depicts the outcrop of the Lias to the northwest of Bath (Phillips, 2003).
The Lias probably takes its
name from the Old French word ‘liais’ referring to hard layered limestone (Webster, 1913). The Lias is characterised by mudstones interlayered with limestones.
(Quelle: British Geological Survey; 2012; Engineering Geology of British Rocks and Soils - Lias Group;
The geology of Oxfordshire
The distinctive landscape of Oxfordshire, with its rounded hills and flat valleys is a wonderful record of the turbulent and diverse history that the county has experienced. If you dig deep enough, Oxfordshire’s geological past can be traced back over 540 million years, although the majority of its visible geology is from the Jurassic Period, almost 200 million years ago. It is from the remnants of this time that Oxfordshire’s aggregate quarries and building stones are found.
The rocks formed in Oxfordshire during the Jurassic Period, and the subsequent Cretaceous Period, were deposited under conditions that are extremely different from those found in Oxfordshire today. During the Jurassic Period, Oxfordshire and its surrounding counties were suffering the fate of a climate similar to that found today in the Bahamas. The whole area was submerged beneath a warm, shallow sea, where corals, fish and small sea creatures thrived.
Today, this can still be seen in many places, particularly some of the old quarries, such as Rock Edge and Magdalen quarries in Headington – both now protected Sites of Special Scientific Interest. Oxfordshire’s famous ‘ragstone’ is really the churned up deposits from the edge of a Jurassic coral reef.
The sticky, blue Lias clays running across the north of the county near Banbury are the oldest of Oxfordshire’s rocks, and they stretch from the Dorset coastline, across the country through Oxfordshire, with the same rocks visible on the Yorkshire coast.
Many of the picturesque villages found throughout Oxfordshire owe their beauty to the Jurassic Oolitic Limestones found locally in Oxfordshire.
Oxfordshire is particularly rich in marine fossils such as bivalves, gastropods and cephalopods, as well as the popular ammonites. There are even a few Cretaceous dinosaurs found in the county, roaming when the warm seas began to subside down the Thames Valley – the footprints of the Megalosaurus and Cetiosaurus left visible in the wet sands at Ardley Quarry near Bicester.
(Open University Geological Society, Oxford Branch Site, 2007; Oxfordshir’e local geology))
Und zur allgemeinen Vertiefung….
*Hemingway, J. E. and Knox, R W O'B. 1973. Lithostratigraphical nomenclature of the Middle Jurassic strata of the Yorkshire Basin of north-east England. Proceedings of the Yorkshire Geological Society, Vol.39, 527-535.
Viel Spaß beim Verinnerlichen
Peter
Thema: Namensherkunft Lias, Dogger und Malm (Gelesen 6530 mal)
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