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Table 2.4. Sedimentary
provinces and associated benthic landscapes of Georges
Bank.(Provinces as
defined by Valentine et al. (1993)
and Valentine and Lough (1991) with additional information from Page C.
Valentine (pers. comm., U.S. Geological Survey, Woods Hole, MA).Benthic assemblages as assigned by Theroux
and Grosslein (1987).See text for
further discussion on benthic assemblages.)
Sedimentary Province
(province no.) |
Depth Range (m) |
Description |
Benthic
Assemblage |
| Northern Edge / Northeast Peak
(1) |
40-200 |
Dominated by gravel with portions
of sand, common boulder areas, and tightly packed pebbles; bryozoa, hydrozoa,
anemones, and calcareous worm tubes are abundant in areas of boulders; strong
tidal and storm currents |
Northeast Peak |
| Northern Slope and Northeast Channel (2) |
200-240 |
Variable sediment type (gravel,
gravel-sand, and sand) and scattered bedforms; this is a transition zone
between the northern edge and southern slope; strong tidal and storm currents |
Northeast Peak |
| North /Central Shelf (3) |
60-120 |
Highly variable
sediment types (ranging from gravel to sand) with rippled sand, large
bedforms, and patchy gravel lag deposits; minimal epifauna on gravel due to
sand movement; epifauna in sand areas includes amphipods, sand dollars, and
burrowing anemones |
Central Georges |
| Central and Southwestern Shelf - shoal ridges (4) |
10-80 |
Dominated by sand (fine and
medium grain) with large sand ridges, dunes, waves, and ripples; small
bedforms in southern part; minimal epifauna on gravel due to sand movement;
epifauna in sand areas includes amphipods, sand dollars, and burrowing
anemones |
Central Georges |
| Central and Southwestern Shelf - shoal troughs (5) |
40-60 |
Gravel (including gravel lag)
and gravel-sand between large sand ridges; patchy large bedforms, strong
currents; minimal epifauna on gravel due to sand movement; epifauna in sand
areas includes amphipods, sand dollars, and burrowing anemones |
Central Georges |
| Southeastern Shelf (6) |
80-200 |
Rippled gravel-sand (medium-
and fine-grained sand) with patchy large bedforms and gravel lag; weaker
currents; ripples are formed by intermittent storm currents;epifauna includes sponges attached to shell
fragments and amphipods |
Southern Georges |
| Southeastern Slope (7) |
400-2000 |
Dominated by silt and clay with
portions of sand (medium and fine), with rippled sand on shallow slopes and
smooth silt-sand deeper |
None |
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