Layered mafic complex
exposed in the eastern Sierra: This aerial view looking up Goodale Canyon
was published in Coleman et al. (1995). The dark foreground rock is a diorite
sill complex that is capped by coeval granite. The granite and diorite are
extensively mingled along the contact, which is subhorizontal and follows
the 10,000' contour. Dark rocks behind the diorite/granite complex are metasedimentary
rocks of the Split Mountain pendant; beyond are granites and diorites of
the Lamarck complex, which is the same age as the Goodale rocks and probably
connects with them beneath the pendant.
Coleman, D. S., Glazner, A. F., Miller, J. S., Bradford, K. J., Frost, T. P., Joye, J. L., and Bachl, C. A., 1995, Exposure of a Late Cretaceous layered mafic- felsic magma system in the central Sierra Nevada batholith, California: Contributions to Mineralogy and Petrology, v. 120, p. 129-136.
Field work in Yosemite National Park: Ph.D. student Kent
Ratajeski has recently begun field studies in Yosemite Valley. There is
a diverse suite of unstudied mafic rocks in and around the valley. Our preliminary
work indicates that The Rockslides (seen here as slopes in front of El Capitan,
left side of photo) is a layered mafic complex like that we described in
Goodale Canyon (Coleman et al., 1995). Other prominent mafic bodies include
dikes cutting El Capitan and diorite bodies in Bridalveil Creek (right side
of photo). 
Mafic-felsic
interaction in the North America Wall, Yosemite: The North America Wall
is named for the eponymously shaped dike of diorite that decorates its face.
The diorite shows mingling relationships with the host El Capitan granite,
suggesting that both were molten at the same time (see closeup for a closer
view). This dike continues across the summit of El Capitan, where it is
magnificently exposed (and more accessible). 
Closeup, North America
Wall: This telephoto view shows what appear to be streamers of diorite
mingled into the host granite, much like fudge-ripple ice cream. Relationships
between diorites and their host granites and granodiorites are complex.
The combination of well- exposed vertical and horizontal surfaces in Yosemite
provides excellent three-dimensional control on the geometries of the magma
bodies. 
Gratuitous photo
of me on the summit of Mt. Agassiz (13,891'): Palisade glacier, one
of the few sad, small glacier remnants in the Sierra, is visible. Prominent
peaks on either side of center are Mt. Sill (14,242') on the left and Thunderbolt
Peak (14,003') on the right; Split Mountain is near the center of the photo
in the distance.
