The geological sciences demand close international cooperation as wel as a rigorous and clearly understood language of words. Nowhere is this more keenly felt than in stratigraphy where, despite the luxury of long philosophical discussions on rocks versus time, many feel a sense of urgency about attempts to achieve a standard global chronostratigraphy. The now wel-known pioneer work of the inte...

Graptolite rhabdosomes display a diverse suite of morphologies. The range of morphotypes present within most moderate to high diversity assemblages from the Ordovician and Silurian is similar, despite the different taxonomic composition of the faunas at different times. Survivorship analyses of graptolite faunas from the Ordovician and Silurian demonstrate strong similarities in the mortality r...

CONTENTS Introduction 85 Brief overview of Cambrian radiation of bilateral animals 86 Rapid diversification of animal phyla 86 Characteristic body plan of each phylum 86 Early establishment of body plan 87 Altered expression of embryonic genes resulting in new body plans 87 Silurian–Devonian radiation of land plants 88 Did early land plants diverge in a rapid evolutionary radiation? 88 Are the ...

lurestan province is petroliferous area. the reserved oil are in ilam and sarvak  (cretaceous ) and kangan ( lower triassic ) and dalan (permian) formations. the lurestan area had high exploration activity but contribution of source rocks in hydrocarbon accumulations isn’t clear. in this paper essential elements and process of hydrocarbon accumulation are introduced. candidate  source  rocks ar...

Xylokorys chledophilia, a new arthropod with three-dimensionally preserved soft tissues, is described from the Herefordshire (Silurian) Lagerstätte of England. The head and trunk are covered by a relatively featureless ovoid carapace, which comprises a domed central part and a flange-like border. The head bears five pairs of appendages. The first is uniramous, with dorsal and ventral projection...

BACKGROUND Sphaerexochinae is a speciose and widely distributed group of cheirurid trilobites. Their temporal range extends from the earliest Ordovician through the Silurian, and they survived the end Ordovician mass extinction event (the second largest mass extinction in Earth history). Prior to this study, the individual evolutionary relationships within the group had yet to be determined uti...

In an earlier paper^ I described the new genus Brooksma from a series of sediments in southeastern Alaska tentatively referred to the upper Silurian. In that paper will be found a brief discussion of the faunal affinities of the series. A more detailed study of the Brooksina fauna together with the famias of lower and liighei horizons strengthens the belief that the formations in question shoul...

Michigan's first commercial oil field was discovered at Port Huron, St. Clair County, in 1886. By 1910, 21 shallow wells had been completed in the Dundee formation at depths of about 500 to 650 feet. In 1910 the daily production from this field amounted to about 10 barrels of oil per day, all of which was used locally in the manufacture of lubricants. However, it was not until 1925 when the Sag...

Core samples from Middle Silurian pinnacle reefs in northern Michigan exhibit a regionally consistent assemblage of late diagenetic phases including geopetal diagenetic sediment, disseminated pyrite, pyrobitumen, rhombic dolomite cement, and equant calcite spar. High (>80°C) fluid inclusion homogenization temperatures and inclusions of Silurian-sourced oil in these diagenetic phases indicate th...