RESEARCH· ·1970·

Bl68
GEOMORPHOLOGY
74°
44°
YERMONT .
. ·N.EW
YORK
25 0 100 200 KILOMETERS
FIGURE1.-Ba:thyme1Jry of the Gulf of Maine (from Uchupi, 1965b). Depth-contom intervallOO and 1,000 m.
data and data from several other profiles taken by the
Woods Hole Oceanographic Institution were used by
Uchupi (1966) and Tagg and Uchupi (1966, 1967) to
describe the' morphology and structure of the Gulf of
Maine, the sounds, and the Bay of Fundy. In this
report, these. data and profiler data from a report by
McMaster and ·others (1968) were used to· determine
the top?graphy of the basement surface. The depth to
basement was computed by assuming a velocity of
sound through water of 1.5 km/sec and through unoonsolidated
sediments of 1.7 kmjsec. The data were
combined with basement topographic maps for the
~orth side of Long Island Sound (U.S. Geol. Survey,
1967), for Long Island (Suter and others, 1949), southeastern
Massachusetts (Oldale, 1969), Cape Cod Bay
(Hoskins and Knott, 1961), and for the outer part of
the shelf, continental slope, and upper continental rise
(Drake and others, 1959). The resulting chart (fig. 3)
shows the configuration of the basement beneath the
Continental Shelf off northeastern United States. A
contour interval of 50 m for depths to 500 m and a
500-m interval for greater depths were used.
GEOLOGY
Exposures along the coast, seismic compressive velocities,.
dredge samples, and seismic-profiler recordings
indicate that crystalline and consolidated rocks of
Paleozoic to middle Mesozoic age form the foundation
of the shelf (Drake and others, 1954, ·1959; Koteff and
Cotton, 1962; Hoskins and l{nott, 1961; McMaster and
others, 1968; Oldale, 1969; Oldale and Tuttle, 1964,
1965; Suter and others, 1949; Tagg and Uchupi, 1966,
1967; Toulmin, 1957; Tuttle and others, 1961; Uchupi,
1966). These rocks are collectively termed "basement"