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Explore Search: Ordovician

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Middle Ordovician rocks of the Tellico-Sevier belt, eastern Tennessee

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A Laurentian margin back-arc: the Ordovician Wedowee-Emuckfaw-Dahlonega basin

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Matthevia (Polyplacophora) invades the Ordovician: The first reported post-Cambrian occurrence

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Cambrian-Ordovician boundary strata in the central Midcontinent of North America

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Middle and Lower Ordovician formations in southernmost Nevada and adjacent California

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Groundwater quality in the Cambrian-Ordovician aquifer system, midwestern United States

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The Shawangunk Formation (Upper Ordovician(?) to Middle Silurian) in eastern Pennsylvania

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Ordovician K-bentonites in the Argentine Precordillera: Relations to Gondwana margin evolution

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Middle and Late Ordovician solitary rugose corals of the Cincinnati Arch region

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Distribution of the Middle Ordovician Copenhagen formation and its trilobites in Nevada

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Late Ordovician-Early Silurian chitinozoans from north-eastern and western Illinois, USA

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Ordovician graptolites of the Basin Ranges in California, Nevada, Utah, and Idaho

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Graptolite succession across the Ordovician–Silurian boundary in south-eastern Alaska

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Carbonate rocks of Cambrian and Ordovician age in the Lancaster quadrangle, Pennsylvania

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Clays Ferry Formation (Ordovician): A new map unit in south-central Kentucky

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Upper ordovician (?) and upper silurian formations of the northern Klamath Mountains, California

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Rhyolitic glass in Ordovician K-bentonites: A new stratigraphic tool: Comment and reply

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Lithostratigraphy of Upper Ordovician strata exposed in Kentucky, with a section on biostratigraphy

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Lithology and origin of Middle Ordovician calcareous mudmound at Meiklejohn Peak, southern Nevada

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Cambrian and Ordovician rocks of southern Arizona and New Mexico and westernmost Texas

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Carbonate-shelf depositional environments of the Ordovician Viola formation in South-Central Kansas

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Collage of USGS Maps.

Lithofacies and stratigraphic nomenclature of part of the Upper Ordovician section of Kentucky

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Zircon from a bentonite bed in Martinsburg shale (Ordovician) at Fisher's Hill, Virginia

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The Ordovician Sebree Trough: An oceanic passage to the Midcontinent United States

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A unique Middle Ordovician K-bentonite bed succession at Röstånga, S. Sweden

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The brachiopod genera Hebertella, Dalmanella, and Heterorthina from the Ordovician of Kentucky

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Lithostratigraphy and depositional environments of the Lexington Limestone (Ordovician) of central Kentucky

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Ordovician sponges from west-central and east-central Alaska and western Yukon Territory, Canada

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Regional water-level changes for the Cambrian-Ordovician aquifer in Iowa, 1975 to 1997

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Petroleum source rock potential of the Upper Ordovician black shale sequence, northern Appalachian basin

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