Drilling during Leg 165 of ODP at five sites in the Caribbean led to the
discovery of a large number (>2000) of volcanic ash layers in the Caribbean
basin, that are attributed to fallout from Central American ignimbrite volcanism
in the Tertiary. The preliminary results are reported in Initital Reports of
ODP, vol. 165. The almost entirely glassy and silicici volcanic ash layers are
truly impressive, some ranging up to 90 cm in thickness at more than 600 km form
possible land sources. Two major episodes of ignimbirte volcanism are identified
and dated in the cores, in the late Eocene and in the Miocene. A more
conprehensive treatment of these ash deposits, their Ar39/Ar40 ages, and
dispersal mechanisms is provided in the the ODP Scientific Results vol. 165 (in
press).
The ODP drilled Caribbean sediment archive (five sites) thus contains a
valuable, well-dated, long (70 m.y.) and very complete record of Central
American voclanism throughout the Tertiary. The geologists who have worked on
the marine record are seeking exchange of information and ideas on the
intergration of the land record of voclanism in Central America with the marine
record discussed above.

Haraldur Sigurdsson, University of Rhode Island

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