GARNET  LEDGE  GARNET  SCHIST

 

A famous collecting locality having abundant garnets is Garnet Ledge, just south of the Stikine River mouth, near the town of Wrangell, in southeastern Alaska, USA.

 

 

 

Many thousands of deep red, gemmy almandine garnets have been collected from Garnet Ledge for over a century.  The land at Garnet Ledge was given to the Boy Scouts in the early 1960s, and ever since, only the children of Wrangell may collect garnets there for free.

 

Garnet Ledge Geology - Almandine garnets occur in grayish-colored schists containing a mixture of sillimanite, muscovite, biotite, staurolite, chlorite, plagioclase, graphite, and ilmenite.  Before metamorphism, the precursor rocks were Late Jurassic-Early Cretaceous fine-grained siliciclastic sedimentary rocks.  These were cooked by contact metamorphism during intrusion of a quartz diorite pluton of the Admiralty-Revillagigedo Plutonic Belt (Alaskan Coast Plutonic Complex) during the early Late Cretaceous (at 89-92 million years).  The garnets appear to have formed over a one million year interval, from 89 to 90 million years ago.  The Garnet Ledge locality is a small, 1.3 square kilometer fragment of roof pendant over the quartz diorite pluton.  Summarized from information in Stowell et al. (2001).

 

Location - Garnet Ledge, adjacent to mouth of Garnet Creek, coastal exposure along the southeastern side of the mouth of the Stikine River, just south of Point Rothsay, just northwest of Garnet Mountain, ~12 km north of Wrangell, southeast of Petersburg, southeastern Alaska, USA (about 56° 34’ 17” North, 132° 21’ 54” West).

 

Garnet schist (5.5 cm across) from the Cretaceous of Garnet Ledge, Alaska.

 


 

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