Recent work has shown that climate, life, and tectonics interact in
ways that are sometimes profound yet not obvious. I review two better
understood terrestrial examples in this paper. First, the development
of compressional orogens is strongly influenced by climate in that the
extent of erosion determines whether high or low mountain ranges develop.
Second, global geochemical processes are strongly influenced by tectonics
and climate. For example, the build-up of oxygen in the Earth's atmosphere
has been aided by deposit of organic-rich sediments in new ocean basins
which prevented reaction of the oxygen with the reduced products of
photosynthesis. The volume of the ocean depends on the extent to which
water is subducted within the oceanic crust and sediments and on the
extent which this water is returned to the surface at island arcs.
Studies of island arc lavas erupted in deep water and 
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indicate that water and sediments are actually subducted to great
depths and are a significant component in island arc volcanics.