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MAP

Topo

Rock Formations

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Topo

Ecoregions

Public Lands

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BASEMAPS

Default Weather

Temperature

Smoke

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WEATHER

Layered gneiss (CTYgn;0)

Geologic Formation in CT, NY, MA

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Lithology

Gneiss

Amphibolite

Amphibolite

Geologic Age

Mesoproterozoic (1600 Ma – 1000 Ma ago)

Geologic Unit Label

Ygn

Gray, medium-grained, well-foliated and generally well layered, light and dark, but locally wispy gneiss, composed of quartz and plagioclase, with microcline locally in the light layers and abundant biotite and common hornblende in the dark layers; garnet or epidote locally. Layers and lenses of calc-silicate rock and amphibolite in some areas.

— USGS

Taxonomy

Classified As

Geologic Formation