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Hook Mt. Basalt (NJJh;5)

Geologic Formation in NJ

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Lithology

Basalt

Geologic Age

Early Jurassic (201.5 Ma – 175.1 Ma ago)

Geologic Unit Label

Jh

(Olsen, 1980) - Light- to dark-greenish-gray, medium- to coarse-grained, amygdaloidal basalt composed of plagioclase (typically An65 and commonly porphyritic), clinopyroxene (augite and pigeonite), and iron-titanium oxides such as magnetite and ilmenite. Locally contains small spherical to tubular cavities (gas-escape vesicles), some filled by zeolite minerals or calcite. Consists of two major flows. Base of lowest flow is intensely vesicular. Tops of flows are weathered and vesicular. Maximum thickness is about 110 m (360 ft) (Olsen and others, 1989).

— USGS

Taxonomy

Classified As

Geologic Formation