| 词条 | Oella Formation |
| 释义 |
| name = Oella Formation | image = Oella Formation outcrop.jpg | caption = Outcrop of Oella Formation located on hillside east of Governor Martin Court, Ellicott City | type = Metamorphic | age = Late Proterozoic or early Cambrian | period = Ediacaran | prilithology = Schist and gneiss | otherlithology = Amphibolite | namedfor = Oella, Maryland | namedby = Willam P. Crowley, Juergen Reinhardt, and Emery T. Cleaves[1] | year_ts = 1976 | region = Piedmont of Maryland | country = {{USA}} | coordinates = | unitof = Wissahickon Group | subunits = Sweathouse Amphibolite Member | underlies = | overlies = Loch Raven Schist | thickness = | extent = Howard and Baltimore Counties | area = | map = | map_caption = }} The Oella Formation is a Late Proterozoic or early Cambrian schist in Howard and Baltimore Counties, Maryland. It is described as "Medium-grained biotite-plagioclase-muscovite-quartz schist, locally garnetiferous, interlayered on a centimeter to decimeter scale with fine-grained biotite-plagioclase-quartz gneiss, commonly bearing muscovite but less commonly garnet."[2] Type localityThe type locality is along the Patapsco River at Oella, southwest Baltimore County.[1] See also{{portal|Geology|Cambrian|Precambrian|Prehistory of North America}}
References1. ^1 Crowley, W.P., Reinhardt, Juergen, and Cleaves, E.T., 1976, Geologic map of the White Marsh quadrangle, Maryland: Maryland Geological Survey, Quadrangle Geologic Map QA-4, scale 1:24,000. ([https://ngmdb.usgs.gov/Prodesc/proddesc_37490.htm online]) 2. ^Crowley, W.P. and Reinhardt, Juergen, 1980, Geologic map of the Ellicott City quadrangle, Maryland: Maryland Geological Survey, scale 1:24,000. ([https://ngmdb.usgs.gov/Prodesc/proddesc_37448.htm online]) 5 : Geologic formations of Maryland|Cambrian System of North America|Schist formations|Baltimore County, Maryland|Howard County, Maryland |
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