Guilford Quartz Monzonite
| Guilford Quartz Monzonite | |
|---|---|
| Stratigraphic range: Silurian | |
Photographed on a boulder at the old Guilford Quarry on Guilford Road, Columbia, Maryland. | |
| Type | igneous |
| Lithology | |
| Primary | monzonite |
| Location | |
| Region | Piedmont of Maryland |
| Extent | central Maryland |
| Type section | |
| Named by | Cloos and Broedel, 1940 |
The Guilford Quartz Monzonite is a Silurian or Ordovician quartz monzonite pluton in Howard County, Maryland. It is described as a biotite-muscovite-quartz monzonite which occurs as discontinuous lenticular bodies which intrude mainly through the Wissahickon Formation (gneiss).
The extent of this intrusion was originally mapped in 1940 as the "Guilford granite". It was given its current name in 1964 by C. A. Hopson. Hopson grouped the Guilford Quartz Monzonite with the Ellicott City Granodiorite and the Woodstock Quartz Monzonite as "Late-kinematic intrusive masses."