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EN
In the sandstones and conglomerates of the Idzików Conglomerate Member (Coniacian), exposed in the Idzików Quarry (SW Poland, Upper Nysa Kłodzka Graben), a moderately diverse assemblage of trace fossils has been recognized. The trace fossils include Arenicolites isp., Asterosoma isp., ?Bergaueria isp., Cylindrichnus isp., Conichnus conicus, Curvolithus simplex, Dactyloidites ottoi, Diplocraterion parallelum, ?Diplocraterion isp., Gyrochorte isp., Gyrophyllites aff. kwassizensis, Macaronichnus segregatis, Ophiomorpha nodosa, Ophiomorpha isp., ?Palaeophycus isp., ?Rhizocorallium isp., Rosselia isp., ?Scolicia isp., Teichichnus isp. and Thalassinoides isp. Escape traces (fugichnia) and some unidentified trace fossils also were found. The following ichnoassociations are distinguished: (IA1) Ophiomorpha-Cylindrichnus, (IA2) Asterosoma-Conichnus and (IA3) Ophiomorpha- Arenicolites. IA1 probably represents a mixture of the impoverished proximal Cruziana ichnofacies and the distal Skolithos ichnofacies, which points to the lower, weakly storm-affected shoreface. IA2 is interpreted as the archetypal Skolithos ichnofacies (opportunistic colonization of tempestite beds) with some elements of the Cruziana ichnofacies (bioturbated, fair-weather background deposits) in the middle, moderately storm-affected shoreface. IA3 is assigned to the archetypal Skolithos ichnofacies, which indicates the upper shoreface-foreshore settings. The trace-fossil evidence implies that the Upper Cretaceous succession was deposited in a shallow, open basin with good oxygenation of the sea floor and normal salinity, under low- to moderately high-energy hydrodynamic conditions. On the basis of ichnological and sedimentological analyses, the deposits studied originated in a system of fan-delta and shallow-shelf settings with common transitional-proximal tempestites. They were deposited in the eastern part of the Upper Nysa Kłodzka Graben during the Coniacian regression.
EN
Three trackways attributable to the ichnospecies Bifurculapes laqueatus Hitchcock, 1858 found in Lower Jurassic rocks of the Newark Supergroup in northeastern North America are preserved in association with current lineations. Each trackway takes turns so that parts of the trackway parallel the current lineations. This parallelism is interpreted as evidence that the trackmakers were entrained in flowing water and had to change course due to the current. If this interpretation is correct, then morphological differences between B. laqueatus and terrestrial insect trackways could be explained by the trackmaker moving subaqueously. Further, B. laqueatus would constitute only the second insect trackway from this region to be recognized as being made subaqueously. From an ecological standpoint, the aquatic insects that made B. laqueatus were probably near the base of the local food chain, the apex predators of which were piscivorous theropod dinosaurs.
EN
The Coniacian quartz sandstones (Żerkowice Member, Rakowice Wielkie Formation) that crop out at quarries near Czaple-Nowa Wieś Grodziska (North Sudetic Synclinorium) contain a low-diversity assemblage of trace fossils: Gyrochorte isp., Ophiomorpha nodosa Lundgren, 1891, Ophiomorpha isp., Phycodes cf. curvipalmatum (Pollard, 1981), ?Phycodes isp., Planolites cf. beverleyensis (Billings, 1862), Thalassinoides paradoxicus Woodward, 1830 and ?Thalassinoides isp. Moreover, interesting compound burrow systems, here referred to as Thalassinoides-Phycodes cf. palmatus and ?Thalassinoides-Phycodes, were recognised at the Czaple Quarry. Additionally, ?Gyrochorte isp., Phycodes cf. flabellum (Miller and Dyer, 1878) and ?Treptichnus isp. were encountered at correlative levels in the Rakowice Małe Quarry. Some of these ichnotaxa have not been recorded previously from Coniacian sandstones of the Żerkowice Member. Additionally, in slabs of these sandstones, the gastropod Nerinea bicincta Bronn, 1836 and the bivalve Lima haidingeri Zittel, 1866 were found. These interesting finds, in particular the gastropods, were already noted from the study area in the first half of the twentieth century by Scupin (1912–1913). Ethologically, the trace fossil assemblage is represented by domichnia or domichnia/fodinichnia (Ophiomorpha, Thalassinoides), fodinichnia (Phycodes) and pascichnia (Gyrochorte, Planolites). The compound burrow systems (Thalassinoides-Phycodes) are interpreted as dwelling/feeding structures. The possible tracemakers are crustaceans (Ophiomorpha, Thalassinoides) or worm-like animals (annelids and other) (Planolites, ?Phycodes, Gyrochorte and ?Treptichnus). The assemblage of trace fossils is characteristic of the Skolithos ichnofacies and Cruziana ichnofacies, typical of shallow-marine settings. Ichnological studies, as well as the presence of accompanying fossils (bivalves, gastropods), confirm the palaeoenvironmental reconstruction of the Żerkowice Member sandstones by Leszczyński (2010). That author interpreted the Coniacian sandstones as bar and storm deposits laid down in a shallow epicontinental sea (mainly the foreshore-upper shoreface; up to the middle shoreface) under normal oxygenation and salinity, in soft substrate, above fair-weather wave base. The deposition of the Żerkowice Member sandstones is linked to a regression that started after uplift of the southeastern part of the North Sudetic Synclinorium.
EN
Miocene deposits in the eastern portion of the Greater Ughelli, Central Swamp and Coastal Swamp depobelts contain well-developed brackish-water trace fossil assemblages. Twelve ichnogenera have been identified, namely: Asterosoma, Bergaueria, Chondrites, Gyrolithes, Thalassinoides, Lockeia, Palaeophycus, ?Conichnus, Planolites, Siphonichnus, Skolithos and Diplocraterion. In addition, common non-descript, passively filled burrows and fugichnia (escape structures) have also been observed. The above-mentioned ichnogenera and associated non-descript structures can be arranged into six distinct and recurring ichnoassociations within the Greater Ughelli, Central Swamp and Coastal Swamp depobelts. Each ichnoassociation is comprised of a group of trace fossils which collectively reflect specific environmental conditions during deposition of these Miocene strata. All trace fossil assemblages illustrate deposition in nearshore, restricted settings. Ichnological and sedimentological criteria which may be utilized to recognise brackish-water deposits are discussed and illustrated in pictures of the cores studied.
5
Content available Ichnotaxonomy as a science
EN
If ichnotaxonomy is to be scientific, then its results must be repeatable. While some ichnotaxa are identified consistently, others are not, suggesting that ichnotaxonomy is not a mature science. When researchers disagree on the identification of a specimen, it suggests that closer examination is needed: an intermediate stage in the scientific method. But when ichnologists publish different names for the same trace fossils, multiple trials of classification have yielded different results, suggesting a failure of the hypotheses that led to the names. The burgeoning of invertebrate ichnology from the 1960s onward was made possible by demonstrating its utility to the petroleum industry; in part, this was accomplished by simplifying the ichnotaxonomy of common trace fossils to the point where a specialist was not required to make use of them in sedimentology and stratigraphy. The biological aspect of trace fossils, albeit of great interest, was downplayed in favour of a severely geometric approach. Ironically, this has had the effect of obscuring basic relationships of trace fossils and their palaeoenvironments that could be of great use to sedimentologists. Previous researchers have emphasized the value of a uniform approach in ichnotaxonomy. To accomplish this, ichnologists should take inspiration from the taxonomy of body fossils. Making ichnotaxonomy more replicable will take time and effort among investigators. In the long run, this can be accomplished by a holistic approach that includes close observation of trace fossils, standardized procedures of description and diagnosis, reinvestigation of type material, attention to bioprint (morphological traits that reveal the anatomical and ethological characteristics of the tracemakers; Rindsberg and Kopaska-Merkel, 2005), avoidance of taphonomic and human bias, and above all, cooperation.
EN
The Upper Triassic Chinle Formation in the Stevens Canyon area in south-eastern Utah represents fluvial, palustrine, and lacustrine strata deposited in a continental back-arc basin on the western edge of Pangea. Previous investigations interpreted a megamonsoonal climate with increasing aridity for the Colorado Plateau towards the end of the Triassic. In this study, we systematically integrate ichnological and pedological features of the Chinle Formation into ichnopedofacies to interpret palaeoenvironmental and palaeoclimatic variations in the north-eastern part of the Chinle Basin. Seventeen ichnofossil morphotypes and six palaeosol orders are combined into twelve ichnopedofacies, whose development was controlled by autocyclic and allocyclic processes and hydrology. Ichnopedofacies are used to estimate palaeoprecipitation in conjunction with appropriate modern analogue latitudinal and geographic settings. In the north-east Chinle Basin, annual precipitation was -1100-1300 mm in the Petrified Forest Member. Precipitation levels were >1300 mm/yr at the base of the lower Owl Rock Member, decreased to -700-1100 mm/yr, and then to -400-700 mm/yr. Two drying upward cycles from -1100 mm/yr to -700 mm/yr occurred in the middle and upper part of the Owl Rock Member. In the overlying Church Rock Member, precipitation decreased from -400 mm/yr at the base of the unit to -25-325 mm/yr at the end of Chinle Formation deposition. Ichnopedofacies indicate monsoonal conditions persisted until the end of the Triassic with decreasing precipitation that resulted from the northward migration of Pangea. Ichnopedofacies in the northeast Chinle Basin indicate both long-term drying of climate and short-term, wet-dry fluctuations.
EN
We describe a new echinoid assemblage, composed of specimens of Bolbaster sp., Cyclaster danicus (Schlüter, 1897), Diplodetus vistulensis (Kongiel, 1950) and Linthia? sp. in a distinctive phosphatic preservation, from the so-called Greensand, a marly glauconitic sandstone horizon at the base of the Danian succession in the Kazimierz Dolny area (central Poland). This assemblage presumably is of early Danian age, with Cyclaster danicus occurring in the lower Danian of Denmark and southern Sweden. The specimens are preserved as internal moulds, composed of phosphatised glauconitic sandstone, occasionally with some test material adhering. The genesis of these moulds involved the following steps: (1) infilling of tests of dead echinoids with glauconitic sand; (2) penetration of the infills by coelobiotic deposit-feeding organisms that produced burrows along the inner test surface; (3) early-diagenetic cementation of infills by calcium phosphate; and (4) exhumation and intraformational reworking of specimens, leading to abrasion, fragmentation and loss of test material in some individuals. Co-occurring are unphosphatised moulds of Echinocorys ex gr. depressa (von Eichwald, 1866) and Pseudogibbaster cf. depressus (Kongiel in Kongiel and Matwiejewówna, 1937), which may represent a younger (middle to late Danian) assemblage. Additionally, the presence of derived late Maastrichtian echinoids, e.g., Temnocidaris (Stereocidaris) ex gr. herthae (Schlüter, 1892), Pleurosalenia bonissenti (Cotteau, 1866) and Hemicara pomeranum Schlüter, 1902, is confirmed for the Greensand, based on new material and re- examination of previously recorded specimens. In summary, members of three echinoid assemblages of different age and preservation occur together in the Greensand. Our results are compatible with former interpretations of this unit as a condensed, transgressive lag with mixed faunas of different age and provenance. However, they are incompatible with the hypothesis that phosphatised Danian fossils preserved in the Greensand are derived from a facies equivalent, now gone, of the lower Danian Cerithium Limestone in eastern Denmark, because all moulds are composed of phosphatised glauconitic sandstone that is utterly different from the calcareous dinocyst-dominated, fine crystalline matrix of the Cerithium Limestone.
EN
Many well preserved trace fossils were found in erratic boulders and the fossils preserved in them, occurring in the Pleistocene glacial deposits of the Fore-Sudetic Block (Mokrzeszów Quarry, Świebodzice outcrop). They include burrows (Arachnostega gastrochaenae, Balanoglossites isp., ?Balanoglossites isp., ?Chondrites isp., Diplocraterion isp., Phycodes isp., Planolites isp., ?Rosselia isp., Skolithos linearis, Thalassinoides isp., root traces) and borings ?Gastrochaenolites isp., Maeandropolydora isp., Oichnus isp., Osprioneides kampto, ?Palaeosabella isp., Talpina isp., Teredolites isp., Trypanites weisei, Trypanites isp., ?Trypanites isp., and an unidentified polychaete boring in corals. The boulders, Cambrian to Neogene (Miocene) in age, mainly came from Scandinavia and the Baltic region. The majority of the trace fossils come from the Ordovician Orthoceratite Limestone, which is exposed mainly in southern and central Sweden, western Russia and Estonia, and also in Norway (Oslo Region). The most interesting discovery in these deposits is the occurrence of Arachnostega gastrochaenae in the Ordovician trilobites (?Megistaspis sp. and Asaphus sp.), cephalopods and hyolithids. This is the first report of Arachnostega on a trilobite (?Megistaspis) from Sweden. So far, this ichnotaxon was described on trilobites from Baltoscandia only from the St. Petersburg region (Russia). Arachnostega on a trilobite (Asaphus), a cephalopod and hyolithids is from Russia or Estonia. Another interesting ichnotaxon is Balanoglossites, which also was encountered in the erratic boulders from the Ordovician Orthoceratite Limestone of Sweden. So far, this ichnotaxon was known only from Russia (St. Petersburg region). Some rare borings (e.g., Osprioneides kampto, ?Palaeosabella isp.) also were found in glacial erratics of Silurian stromatoporoids, excellent outcrops of which are located in Gotland (Sweden) and Saaremaa (Estonia). In addition, stromatoporoid/coral, coral/coral and some new fossil associations are reported. The material studied probably was transported from the N, the NE, and less commonly from the NW.
EN
The Middle Jurassic Kaladongar Formation, Patcham Island, Kachchh, western India, comprises of a 353 m-thick mixed siliciclastic-carbonate succession of asymmetrical shallowing and deepening upward sedimentary cycles. It is subdivided into five main facies i.e., micritic sandstone, allochemic sandstone, sandy allochem limestone, micritic mudrock, and sandy micrite along with shales and conglomerates. Eight trace fossil assemblages comprising 34 ichnogenera are defined, including the Asterosoma, Gyrochorte, Rhizocorallium, Thalassinoides, Planolites–Palaeophycus, Phycodes, Ophiomorpha, and Skolithos assemblages that reflect five depositional facies: offshore, transitional, lower, middle, and upper shoreface. The sedimentary packages and associated trace fossil assemblages are separated by various discontinuities, stratigraphic surfaces and stratigraphic boundaries within the succession of the Kaladongar Formation and reveal three phases of regression (RST-I, RST-II and RST-III) and three phases of transgression (TST-II, III and IV) within the 3rd order systems tracts developed in the slowly transgressing sea during the Bajocian-Bathonian time interval.
10
Content available The use of the terms trace, mark and structure
EN
Mark, trace and structure have been in consistently used in ichnology for many years; we wish to clarify the origins and to prescribe correct usage of these terms. The origins of the words are ancient and complex; in the twentieth century they were given clear definitions as ichnologic terms. Seilacher (1953) defined a mark (German Marke) as a physical (abiogenic) sedimentary structure, as in the common terms sole mark, flute mark, but not bite mark or scratch mark. Trace has been defined many times; we recommend the consensus definition of Bertling et al. (2006) as “a morphologically recurrent structure resulting from the life activity of an individual organism (or homotypic or ganisms) modifying the substrate”; this in cludes dwelling trace, feeding trace, bite trace. Structure, as implied in another consensus paper (Frey, 1973), is a neutral term for geologic patterns resulting from either biogenic or abiogenic processes. Use of the three terms in a clear consistent manner will aid communication both among ichnologists and between ichnologists and their colleagues in other fields.
11
Content available In defence of an iconic ichnogenus : Oichnus Bromley
EN
By establishing the bioerosion ichnogenus Oichnus, Richard Bromley (1981) addressed ‘small round holes in shells’ and catalysed a series of still ongoing discussions on ichnotaxonomical principles. In a recent revision by Zonneveld and Gingras (2014), Oichnus was rejected, together with Tremichnus Brett, 1985 and Fossichnus Nielsen, Nielsen and Bromley, 2003, by means of subjective synonymisation with the presumed senior synonym Sedilichnus Müller, 1977. However, Sedilichnus is nomenclaturally unavailable, because it is an atelonym (conditionally proposed). In addition, reinvestigation of the type material of ‘Sedilichnus’ shows that it probably describes variably shaped oscula and thus is a genuine morphological character of the host sponge Prokaliapsisjanus, rather than a bioerosion trace fossil. The ichnogenera Oichnus and Tremichnus are re vised, leading to the synonymisation of Balticapunctum Rozhnov, 1989 with Tremichnus, and of Fossichnus with Oichnus. The refined ichnogeneric diagnoses return Oichnus to complete or incomplete bioerosive penetrations in calcareous skeletal substrates, commonly interpreted as praedichnia with or without signs of attachment, while Tremichnus (now including O. excavatus) exclusively refers to shallow pits passing into echinoderm skeletons that are interpreted as domichnia or fixichnia.
12
Content available Construction of ichnogeneric names
EN
Ichnologists have over used the root ichn- “trace”, employing it in new terms and new ichnogenera alike, to the point where it can be difficult to express one self clearly without using it several times in one sentence. The root derives from Ancient iχνος (ichnos), which means “foot print” or “track”, or by extension a “trace”, any sign of an animal’s activity. Perhaps it is time to explore the use of other roots to create new ichnologic terms and genera. Alternative Latin and Greek roots are given here, as well as ad vice on how to construct new ichnogenera in a technically correct and aesthetically pleasing manner.
EN
Enrolled specimens of trilobite species Strenuella polonica, partly preserved within their escape structures and burrows from the Cambrian Series 2 Ociesęki Sandstone Formation, are described. The specimens are interpreted as buried during storm episodes. Their occurrence in a few horizons, the presence of non-bioturbated tempestites with combined wave-current ripples and groovemarks interbedded with bioturbated beds suggest a depositional environment between normal and storm wave base. The trace fossils Monomorphichnus and some Rusophycus have been interpreted as structures formed during the storm when animal tried to take refuge. Well-preserved syndepositional Rusophycus and its different taphonomic variants are discussed. The part of the Ociesęki Sandstone Formation studied is interpreted as deposited on a lower shoreface with storm influence.
EN
Two types of large, branched structures from the Lower Pleistocene (Calabrian) high-energy calcarenites of Favignana Island are described: Faviradixus robustus gen. et sp. nov. and Egadiradixus rectibrachiatus gen. et sp. nov. They may be interpreted as root structures of large plants, trees and trees or shrubs, respectively. The former taxon co-occurs with the marine animal trace fossils Ophiomorpha nodosa, Ophiomorpha isp., Thalassinoides isp. and Beaconites isp. The interpretation as root structures although tentative is probable and can be related to short emergence episodes for the formation of E. rectibrachiatus or to longer emergence, responsible for the discontinuity at the base of the overlying Tyrrhenian deposits, for F. robustus. Calcified root mats of smaller plants associated with the Tyrrhenian or younger emergence surfaces are common.
EN
The pascichnial trace fossil Bichordites kuzunensis isp. nov. occurs as an epichnial complex structure in early Oligocene prodelta sediments of the Thrace Basin in Gokceada Island, northwest Turkey. It displays characteristics of irregular echinoid burrows such as overall shape and a double meniscate filling with a chevron dorsal suture, in addition to the feature typical of the so far monospecific Bichordites Plaziat and Mahmoudi, 1988, that is a single central core around a single drainage tube. Its miniature size can be related to the small size of the tracemaker (ontogenic feature) or to its dwarfism in a stressed deltaic environment (palaeoecological feature). Its occurrence indicates a period of fully marine conditions during accumulation of the deltaic sediments of the Mezardere Formation.
EN
A complex trace fossil that requires a three-dimensional (3D) reconstruction is described and interpreted. The specimens studied are assigned to a new ichnospecies (Hillichnus agrioensis) of Hillichnus Bromley et al., 2003. Most of them are uncollectable and a compound iconotype was designed to characterise the new ichnospecies. The three-dimensional trace fossil has been recorded in marginal-marine deposits close to the top of the Agrio Formation (Lower Cretaceous of Neuquen Basin, Argentina). The new ichnospecies shows a different pattern of feeding than H. lobosensis Bromley et al., 2003, and records defaecation downward in the deeper preservational level (level 4). Feather-like structures (level 2) that typify the ichnogenus also record the activity of an inhalant siphon and indicate a retractile movement. The vertical shafts (level 1) are scarcely recorded. Aligned double rings also document the infaunal habit of the tellinid bivalves that are considered the most likely producers of the trace. It is clear that when only level 2 is exposed, in some cases this form can be assigned to Jamesonichnites heinbergi Dam 1990a consequently, this ichnospecies is interconnected with more than one ichnogenus. Vertical projections recorded in branches differ from the type ichnospecies H. lobosensis Bromley et al., 2003. The occurrence in marginal-marine facies is congruent with the record of Jamesonichnites but not common in the type species and similar to those more frequent in deep-sea deposits (e.g. Polykampton alpinum Ooster, 1869).
EN
The trace fossil Osculichnus labialis igen. et isp. nov. occurs as hypichnial pairs of uneven bilobate mounds in early Oligocene prodelta sediments of the Thrace Basin. Osculichnus is generally elliptical or crescentic in outline and has two lip-like lobes: a smaller and a larger one, which are separated by an undulate furrow. Herein, it is interpreted as a hunting trace (praedichnion) of a fish penetrating a surficial sand layer and into an underlying mud horizon. The fish hunted for small endobenthic bivalves and perhaps other invertebrates such as polychaetes. Penetration into surficial mud rather than sand resulted in poorly preserved variants of this trace fossil, whose median furrow is commonly not visible. The probability of fish trace makers is supported by experiments.
EN
Graphoglyptids are diagnostic ichnofossils of the Paleodictyon ichnosubfacies (Nereites ichnofacies), which is well represented in deep-marine Mesozoic.Cenozoic thin-bedded turbidites. However, unusual shallow-water records of Mesozoic-Cenozoic Paleodictyon and particular preservational restrictions of graphoglyptid burrows introduce the question of whether graphoglyptids are reliable bathymetric indicators. We document and discuss another unusual graphoglyptid association preserved in shallow-marine, high-energy, organic-rich, and bioturbated turbidites of leveed channels in the upper middle Eocene CCa member, Cerro Colorado Formation, Fuegian Andes. The member includes the facies associations: 1) mudstones, 2) interbedded mudstones and thin-bedded Tbc turbidites, and 3) thick-bedded sandstones andmudstones. Facies association 3), interpreted as channel deposits, records at least three horizons with Desmograpton, Glockerichnus, Helicolithus, Helminthorhaphe, Megagrapton, Paleodictyon and Urohelminthoida. Associated beds are lenticular, channeled sandstone turbidites with marked basal erosion surfaces and variable proportions of interbedded mudstone-sandstone with high content of plant debris. Trace fossils in the channeled sandstones are dominated by Ophiomorpha rudis and O. annulata; mudstones within the thick-bedded mudstone-sandstone beds bear Nereites, Phycosiphon, Zoophycos and Paradictyodora, with subordinate Schaubcylindrichnus, Tasselia and Scolicia. The unusual preservation of limited graphoglyptid-bearing beds within a highly energetic and bioturbated interval seems to support the concept that preservational restrictions on graphoglyptid burrows could be locally more important than bathymetric constraints.
19
Content available remote Da Vinci's Paleodictyon : the fractal beauty of traces
EN
The origins of ichnology are located in a land of convergence between Art and Science, in a historical period - the Renaissance - during which the scientific method had its birth. Trace fossils were studied and graphically represented by preeminent naturalists such as Leonardo da Vinci, Konrad Gesner, Johann Bauhin and UlisseAldrovandi - who defined ichnofossils as "exceptionally beautiful". In this study, the representation of trace fossils in the Renaissance is explored by employing a method widely used in studying visual perception - fractal geometry. In particular, this paper focuses on the reasons for the aesthetic appeal of traces and proves that (1) the aesthetic perception of traces is closely tied to their fractal dimension, and (2) many traces are aesthetically appealing because they have fractal behaviour. In particular, graphoglyptids and chondritids display significant fractal-like features that are linked with their constructional program and function. Such fractal traces are hierarchically structured and their whole geometric structure can be regarded as an expression of self-organization processes producing correlations between different orders of scale.
EN
Integrated sedimentological and palaeontological study of borehole cores through plat orm siliciclastic deposits of the southernmost part of Brunovistulicum (S Moravia) shows convincing evidence for the Cambrian age of a considerable portion organic-walled microfossils of Late Proterozoic (Ediacaran) age have been found in a sample from the Menín-1 borehole. Thirty genera characteristic of the Ediacaran have been recognized. Part, though, of the siliciclastic succession of S Brunovistulicum is Devonian in age. The platform deposits studied are consid red to have the same source area but the degree of maturity of the Devonian clastics rocks is generally higher than that of the older strata. Facies analysis indicates a predominance of deltaic settings (braided and fan del tas); similar sedimentary environments are suggested for both the Ediacaran/Cambrian and Devonian successions.
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