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Re: Mesozoic Volcanoes?



> > Does anyone here know what periods of the Mesozoic there were volcanoes in?
> > Thanx,
>
>The simple answer - all of them.
>

Indeed.  Remember, the Cretaceous alone is ~15 million years longer than
the whole of the Cenozoic, so there were a LOT of volcanoes during the
Mesozoic.

Some big or otherwise noteworthy incidences were:

Late Triassic and Early Jurassic, along the rift valley which is now the
Atlantic, there were many many periods of intense vulcanism.  The regions
involved are now the eastern coasts of South and North America and
Greenland, and the western coasts of Europe and Africa.

Late Cretaceous, the North American West - increased vulcanism associated
with the Laramide Orogeny (the uplift of the Rocky Mountains and other
parts of the Cordillera system).

Late Cretaceous-Early Paleogene, India - the Deccan Flood basalts, which
produced vasts amounts of lava flooding a huge region of India.  These
flows began ten million years or more before the end of the Cretaceous, and
ended well into the Tertiary.

There are many others, of course.  One nice aspect of volcanic deposits is
that they allow for radiometric dating.  Thus, fossils found interbedded
between ashes/lavas/whatever from the above are fairly easy to date
chronologically.
                                     
Thomas R. Holtz, Jr.
Vertebrate Paleontologist in Exile
U.S. Geological Survey
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092

email:  tholtz@geochange.er.usgs.gov 
Phone:  703-648-5280
FAX:            703-648-5420