Home | Session 1 | Plate boundaries 1, 2
Plate boundaries and plate tectonic implications
Presented
by Carol Tang
California Academy of Sciences
II. Implications of Plate Tectonics:
Effect on life:
a. Major mass extinctions may be a result of continental configuration
- climatic consequences (Pangaea means more extreme climates in centers of continents
- extent of shorelines (Pangaea means less shoreline for marine organisms on shallow shelves).
b. Distribution of life (Biogeography). There are two models we talked about where plate tectonics affects the distribution of fossils and living organisms.
- Viking Funeral Ship model, like in activity "Evidence for Continental Drift." The fossils are carried to new places by plate tectonic activity-after organisms had already died.
- Noah's Ark model is where living organisms are carried along when the continent they live on moves due to plate tectonics. So this can be used to explain the modern distribution of flightless birds, which live on remnants of Gondwanaland (they evolved and spread out to the all the southern continents while the continents were still connected. As the continents moved apart, the populations became separate by large oceans.)
Effect on climate:
a. Carbon dioxide. Volcanic degassing produces CO-2, weathering (often associated with major mountain-building) draws down CO-2.
b. Circulation of oceans. Ocean currents distribute heat. With isolation of Antarctic due to plate tectonics (break up of Pangaea and Gondwanaland), a circum-Antarctic current developed, which cooled down Earth and led to modern oceanographic/climatic conditions.
updated January 28, 2002
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