| Alaska, 1979 | |
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The sides of Tarr Inlet have spectacular exposures of deep bedrock. Note the large dikes on the left side, warped after their emplacement. This terrane was once far to the south, but plate tectonic interactions carried it north and cemented it against the side of the North American plate.
The large body of light-colored rock may be a granitic intrusion into the darker gneiss above and below it, or it might have ended up here after crustal extension and compression shuffled pieces of the crust like a deck of cards. It takes close-up inspection of the rocks plus wide-ranging knowledge of the region to make a better guess.
