Skagit Gneiss (Misch, 1952) has been restricted by Misch (ms) to include gneisses that can be demonstrated to be product of migmatization of sedimentary-volcanic sequence, and gneisses of doubtful origin. The gneisses that can be shown to be derived from plutonic rocks are now excluded from Skagit Gneiss (restricted). These include: Eldorado Orthogneiss, Gabriel Peak Orthogneiss, Bonanza Orthogneiss.

Source: GNU records (USGS DDS-6; Menlo GNULEX).

Near eastern border of Skagit Gneiss in Northern Cascades, northern Chelan Co, WA, presumed basement elements include Gabriel Peak quartz dioritic orthogneiss, southeast of Ross Lake. [age not stated]

Source: GNU records (USGS DDS-6; Menlo GNULEX).

In southeast part of map area [Northern Cascades of WA] Skagit Gneiss is bordered by band of lower grade, predominantly quartz-dioritic orthogneiss [Gabriel Peak]. Igneous rock was cataclastically sheared and recrystallized moderately well in albite epidote and oligoclase-epidote amphibolite subfacies. At least part of contact with Skagit Gneiss is tectonic. On south, orthogneiss seems to grade into Black Peak batholith. Further north it is cut by Ross Lake fault. Though the orthogneiss band trends northwest, its internal structure strikes northeast in an area where adjacent Skagit Gneiss and, east of Ross Lake fault, Elijah Ridge Schist strike northeast too. Orthogneiss, first considered basement(?), is probably derived from post-Skagit Suite intrusive, but the sheared northeasterly strike remains unexplained. Is considered Paleozoic(?) age.

Source: GNU records (USGS DDS-6; Menlo GNULEX).