| Oella Formation | |
|---|---|
| Stratigraphic range: Late Proterozoic or early Cambrian | |
 Outcrop of Oella Formation located on hillside east of Governor Martin Court, Ellicott City | |
| Type | Metamorphic |
| Unit of | Wissahickon Group |
| Sub-units | Sweathouse Amphibolite Member |
| Overlies | Loch Raven Schist |
| Lithology | |
| Primary | Schist and gneiss |
| Other | Amphibolite |
| Location | |
| Region | Piedmont of Maryland |
| Country | United States |
| Extent | Howard and Baltimore Counties |
| Type section | |
| Named for | Oella, Maryland |
| Named by | Willam P. Crowley, Juergen Reinhardt, and Emery T. Cleaves [1] |
| Year defined | 1976 |
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]
