RESEARCH· ·1970·

in this report. In places, the basement offshore is probably
composed of weakly metamorphosed to unmeta­
·morphosed sedimentary and volcanic rocks similar to
those in the Narragansett and Boston basins and northern
New England (fig. 2). Triassic sedimentary rocks
make up a large part of the basement in northeastern
Gulf of Maine and the Bay of Fundy (Tagg and
Uchupi, 1966) and probably occur in Long Island
Sound as extensions of the Triassic basins in Connecticut.
The oldest unconsolidated sediments known to occur
on the glaciated shelf are the Upper Cretaceous deposits
exposed on Long Island, Block Island, and Mar-
OLDALE AND UCHUPI
B169
tha's Vineyard. Similar rocks, possibly folded, are believed
to occur in Georges Basin (Uchupi, 1966) and
as erosional remnants in Cape Cod Bay and Massachusetts
Bay (Hoskins and Knott, 1961). In most
areas, the Cretaceous deposits rest directly on basement.
Gently dipping or folded sedimentary rocks of possible
Triassic or post-Triassic age occur in closed depressions
in the deepest parts of Wilkinson and Maury
Basins (U chupi, 1966). Sediments of Eocene ( ? ) age
have been found in boreholes on outer Cape Cod (Zeigler
and others, 1960) and are inferred to occur in Cape
Cod Bay (Hoskins and Knott, 1961) . Eocene sediments
74 °
EXPLANATION
44 •
Eocene(?) sediments
Tertiary and Cretaceous
sediments, undifferentiated
Triassic -igneous and
sedimentary rocks
Triassic (? ) igneous and
sedimentary rocks
Carboniferous sedime ntary rocks
r7TI
LL_]
Paleozoic and lower Mesozoic
igneous and metamorphic rocks
Location of ship tracks
where depth to base- .
ment was determined·
NEW HAMPSHIUE .. ·
NEW
YORK
42
25 0
'100 200 Kl LO M ETE RS
FIGUUE 2.-Geologic map showing distrli:bution of pre-Pleistocene rocks. Distribution of sedimentary, igneous, and m€il:amorphic
rocks offshm•e based ()ill continuous seismic-profHer data (Hoskins and Knott, 1961; Uchupi, 1966; Tagg and Uehupi, 1966,
1967; McMaster and others, 1968) and on dre