Oella Formation

{{Short description|Cambrian schist in Maryland}}

{{Infobox rockunit

| 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. CleavesCrowley, 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])

| 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."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])