Port Deposit Gneiss
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| Port Deposit Gneiss | |
|---|---|
| Stratigraphic range: Paleozoic | |
 Polished slab of the Port Deposit Gneiss, about 10.7 cm wide | |
| Type | metamorphic |
| Lithology | |
| Primary | gneiss |
| Location | |
| Region | Piedmont of Maryland |
| Extent | eastern Maryland |
| Type section | |
| Named for | Port Deposit, Maryland |
The Port Deposit Gneiss is a Paleozoic gneiss formation in Cecil County, Maryland. It is described as a "Moderately to strongly deformed intrusive complex, chiefly composed of quartz diorite gneiss. Rock types include gneissic biotite-quartz diorite, hornblende-biotite-quartz diorite, and biotite granodiorite, with minor amounts of quartz monzonite and hornblende-quartz diorite. Moderate protoclastic foliation grades into strong cataclastic shearing."[1] It intrudes into the Volcanic Complex of Cecil County.
