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The following Miocene fossils from Skonun point were
collected by the author and were determined by Dr. Ralph
Arnold:

Paplia sp. C.

Caesia sp. K.

Cryptonatica clausa B. and S.

Henmimacira cf. albaria Conr.

MASSET FORMATION.

Distribution. The Masset formation is a name applied to
the late Tertiary volcanic rocks of Graham island, which form
virtually all of the surface rocks west of Masset inlet and north
of Rennell sound, and which occur in other parts of the island
as well. These rocks are well exposed along the north and west
coasts, around Masset lake in the interior, and in the Slatechuck
range in the southern part of the island.

Lithology. The Masset rocks are almost wholly basaltic.
Bedded flows and coarse agglomerate beds (Plate XIIA) make
up nearly all of the formation. The basalts are characteristic-
ally dark grey or black, heavy rocks, and range in texture from
glassy to highly porphyritic types. Amygdaloids are abundant,
the amygdules being filled with chalcedony, quartz, calcite, and
occasionally black sticky tar. Basaltic glass or tachylyte has
been found on Ship Kieta island, in Masset inlet, and in some
of the streams entering Athlow bay on the west coast. It is
reported also from the west side of Juskatla inlet. Agglomerates
in bewildering varieties of shape, size, and proportion of frag-
ment to matrix, occur interbedded with the flows. Fine-
grained, bright greenish and bluish, curiously banded tuffs
are found near Tian head on the west coast and elsewhere in
that vicinity. These are the rocks in which it is hoped by some
to find petroleum by drilling.

Besides the pyroclastic rocks, sediments of detrital origin
make up a part of the Masset volcanics. They were seen on
the southeast slope of Slatechuck mountain, but were not care-
fully studied. Some of the beds are conglomerates, composed
of pebbles of volcanics up to 6 inches in diameter, in a dense