Magothy Formation quartzite, 18AN0760, Anne Arundel County, Maryland.
A sample of Cretaceous Mogothy Formation Quartzite was collected near Pasadena in Anne Arundel County, Maryland (18AN760). The site is a large topographic inland knoll with associated waste and chipping debris. Additional exposures of the formation occur at the mouth of Rock Creek along the south side of the Patapsco River (“White Rocks”). Inundated quartzite strata have been reported offshore of Rocky Point at the mouth of Back River in Baltimore County, Maryland and at the mouth of Stony Creek in Anne Arundel County.
Magothy Quartzite can have a coarse to fine grain texture that is gray, gray-blue, or purple color when fresh. It is composed of opaline cemented quartz sand. Sometimes the material has a distinct banding. Highly weathered samples usually have a white to tan color. The quartzite has small particles of lignite which gives the material a distinctive “peppered” appearance.
Magothy quartzite does not seem to be visually distinctive enough to be readily apparent in regional collections. If Magothy quartzite were represented in assemblages, it would be hard to determine whether it was derived from the principle quarries or from eroded secondary context.
Prepared By Egloff 2008