Browse Map

Explore away

Explore Map Collection

Check out our basemaps

Print a Map Plus

Generate a high-quality PDF

Field Guide

Discover local flora, fauna, geology, and more

Local Flora & Fauna

Learn the ecology of your area

Local Geology

Learn the geologic formation at your feet

Get Started or Sign In

Welcome

Continue with Apple

Already have an account? Sign In

MAP

Topo

Measure

Topo

Ecoregions

Public Lands

...

BASEMAPS

Default Weather

Temperature

Smoke

...

WEATHER

Elk Park Plutonic Group - Biotite augen gneiss (VAYep;0)

Geologic Formation in NC, VA

Print Map

Generate High-Quality PDF

Lithology

Gneiss

Geologic Age

Mesoproterozoic (1600 Ma – 1000 Ma ago)

Geologic Unit Label

Yep

Elk Park Plutonic Group (Yep, Yec; Rankin and others, 1972; 1973) Includes augen gneiss and porphyritic gneiss (Yep), and equigranular quartz monzonite, quartz monzonite flaser gneiss, and quartz monzonite gneiss (Yec). Rocks range in composition from diorite to quartz monzonite; most are quartz monzonite in which the primary dark mineral is biotite, with or without hornblende; epidote and titanite are common accessory minerals. Porphyritic rocks contain microcline phenocrysts. Augen gneiss was probably derived from porphyritic plutonic rocks by shearing. This unit includes in part the Little River Gneiss of Dietrich (1959) and Cranberry Gneiss (Rankin and others, 1972; 1973). U-Pb zircon data from the Cranberry has been interpreted to signify ages of 1050 Ma (Davis and others, 1962) and 1080 Ma (Rankin and others, 1969).

— USGS

Taxonomy

Classified As

Geologic Formation