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Our first stop was at the entrance to the Academy Quarry northeast of
Fresno. Dave Liggett spoke about the geology of the Academy pluton, the
significance of the hornblende-bearing mafic rocks at the western margin of the
Sierra Nevada batholith, and their intrusion along a boundary between the
ophiolitic rocks to the west and the continental rocks to the east. He also
gave a brief history of the Academy Quarry.
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Day two
started with a presentation by George Dunne on everything you wanted to know
about the batholith (geography, glaciation, chemical trends across the batholith and
within intrusive suites, pluton age progression across the batholith,
structural trends, shear zones and their significance, uplift and tilting of
the batholith, and the location and significance of the prebatholithic wall rocks).
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We drove to Big Creek, then up a steep, narrow, winding road (with a "WATCH
FOR LOGGING TRUCKS" sign) where we stopped at an 8 Ma xenolith-bearing volcanic
pipe.
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Here we discuss how the volcanic pipe and others like it in this region have been used to
construct a model of the structure and composition of the lower crust and mantle
beneath the central Sierra. Xenoliths from younger volcanic pipes and
flows contain a different suite of rocks which suggests that the lower crust had
been removed during the intervening time. Keith Putirka (back row third
from left) CSUN alumnus and professor at CSU, Fresno joined us for the trip.
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We drove past Huntington Lake to the Portal Power Station where Dave Liggett
presented a history of the development of hydroelectric power in the San Joaquin
River drainage. Through a series of lakes, dams, tunnels, and power
houses, the same water is used nine times to generate electricity and is said to
be the "hardest working water in the world"!
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Some of the group enjoying the view at White Bark Vista on our lunch stop.
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Our caravan of cars drove the one lane, winding, Kaiser Pass road to Lake Edison
where we set up camp.
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We had some free time to pursue things like swimming, hiking, Frisbee, and Hacky
Sack.
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Our gourmet chef prepares an epicurean delight. | | | | | | |