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Geology of the Adirondack Mountains (cont.)

Adirondack Highlands (cont.)

4.2 AMCG Suite

Roaring Brook Falls, carved in anorthosite, Adirondacks, New York


Figure 4-6. Base of Roaring Brook Falls, Adirondacks, New York.

The falls, south of Keene valley, are carved in anorthosite. Water, not visible here, falls through the narrow incision in left background.


Anorthosite close-up at Roaring Brook Falls


Figure 4-7. Anorthosite close-up at Roaring Brook Falls.

Off-white plagioclase, blue andesine and black pyroxenes. Width of field: 11 cm.


Anorthosite with mafic intrusions near Elizabethtown, New York


Figure 4-8. Anorthosite in The Branch bed, north of Elizabethtown, Adirondack Highlands.

White anorthosite intruded by darker gabbro or anorthositic gabbro and a mafic vein. Quarter for scale.


Anorthosite and felsic veins in The Branch bed, New York


Figure 4-9. Anorthosite in The Branch bed.

Same area as in fig. 4-8. Similar gabbro intrusions and felsic veins. Quarter for scale.


Anorthosite and gabbro near Split Rock Falls, Adirondacks, New York


Figure 4-10. Anorthosite and gabbro near Split Rock Falls, south of Elizabethtown.

Spectacular mix of white anorthosite and dark gabbro blocks, deformed by metamorphism. Hammer for scale.


Close-up of gabbroic anorthosite near Split Rock Falls, Adirondacks


Figure 4-11. Close-up of gabbroic anorthosite near Split Rock Falls.

Same outcrop than in preceding figure. Deformation is well visible. Hammer for scale.


Close-up of gabbro near Split Rock Falls, Adirondacks


Figure 4-12. Close-up of gabbro near Split Rock Falls.

Notice the numerous garnet crystals. Quarter for scale.


1 Overview

2 Lowlands

3 Carthage-Colton Shear Zone

4 Highlands:
4.1 Older rocks

4.2 Highlands: AMCG suite (this page)

4.2 Highlands: AMCG suite (cont.)

4.3 Highlands: Miscellaneous rocks

References (opens in new tab)