| 词条 | Glenwood Shale |
| 释义 |
| name = Glenwood Shale | image = | caption = | type = Formation | age = Ordovician | period = Ordovician | prilithology = | otherlithology = | namedfor = | namedby = | region = | country = United States | coordinates = | unitof = | subunits = | underlies = Platteville Formation | overlies = St. Peter Sandstone | thickness = | extent = Minnesota | area = | map = | map_caption = }}{{Paleozoic Stratigraphy of the Upper Midwest}} The Glenwood Shale is a thin Ordivician shale formation in the sedimentary sequence characteristic of the upper Midwestern United States. It lies under the Platteville Limestone and above the Saint Peter Sandstone. Together, these three units represent a sequence of sea-level rise during Ordovician time. Because it is often very thin (~10 cm or less in the Twin Cities), it is often ignored in the general stratigraphy. ReferencesUniversity of Minnesota: River Bluffs homepage{{US-geologic-formation-stub}} 4 : Ordovician System of North America|Shale formations of the United States|Ordovician Minnesota|Ordovician geology of Wisconsin |
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