The stratigraphic relationships and distribution
of 36 named late Quaternary (<c. 50000 yr BP.) silicic tephra
formations, erupted from 4 volcanic centres--Okataina,
Taupo, Maroa, and Tuhua (Mayor Island)--are presented.
The stratigraphy and status of several other named late
Quaternary tephras are also discussed. This compilation
brings together all the data, currently scattered through many
publications, to make tephrostratigraphy more accessible and
more easily used. The nomenclature of tephra formations is
discussed and some rationalisations are suggested. The term
"tephrology" is suggested as an appropriate title for the field
of tephra studies. The deletion of grain-size (ash, lapilli),
shape (breccia), and lithologic (pumice) terms from all
formation names is recommended, as is standardisation on a
"Tephra Formation" format Several tephra layers not
previously formally named, or without designated type
sections, are defined. The dominant ferromagnesian mineral
assemblage of each tephra formation has been compiled as an
aid to tephra identification. All available radiocarbon ages
(384) on each tephra formation are presented, and each age is
assessed for reliability in dating the eruption of that tephra.
The standard-deviation weighted mean age of the reliable
ages has been determined as the best current estimate of the
age of each tephra. At least 10 tephra formations have no
reliable ages, and efforts should be made to date these.
