In some ways, mountain ranges are like icebergs bobbing in the sea. The tallest
icebergs have the largest underwater counterpart and the highest mountains have
the deepest crustal roots. The southern Sierra Nevada in California, however,
has an anomalously thin crust. Using seismic imaging, geologists have observed
that something is missing: the Moho, a seismic discontinuity named after the
Croatian seismologist Andrija Mohorovicic, that marks the boundary between the
bottom of the crust and the top of the mantle. The research highlights a unique
mountain-building process and may help explain the Sierras stunning topography.
For the full story, visit www.geotimes.org/WebextraArchive.html or go to the Sept. 2 Web Extra.
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