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tabular, platforms. The topography of the continental shelf in this area is characterised by a
plateau in the middle part, with an average depth of 150 m (Malta plateau). The shelf is
flanked by a submarine ridge, which protrudes as a submerged extension of Cape Passero
and embraces the shelf area along the eastern and southern perimeter. The Maltese Islands
represent the emerged part of this ridge while Hurd bank to the north east of Malta shallows
to a depth of just over 50 m.
Of particular interest is the Medina bank, southeast of Malta. This elongate topographic high
serves as important barriers to water masses flowing across the platform.

The Medina uplift is characterized by a broad, convex-up topography (probably gentle
anticlinal-like folds) and small distinct valleys. Faulting is not as prominent a feature in this
zone as in the other outer margin environments of the Channel. The reduced sediment cover
on the convex-up topography suggests a slow, uniform rate of sediment accumulation, or
erosion by bottom currents or both (Maldonado and Stanley, 1976).

The positive Medina bank feature is bisected by a local graben, along the north side of which
is the poorly defined ridge of the West Medina bank (Bishop and Debono, 1996). On its
eastern extremity, it deepens abruptly into the deep Ionian sea with a very sharp escarpment
(Malta Escarpment) and, likely, it continues into the Medina-Malta ridge, protruding into the
Ionian Abyssal Plain as sub-bottom tectonic structure (Medina - Victor Hansen structure).

The strait between Cape Bon (Tunisia) and Cape Lilibeo (Sicily) is the narrowest constriction
(1243km wide) and constitutes the main exchange passageway for the superficial and
intermediate water masses between the two sub-basins. The flow is further limited by the
highly irregular bottom topography of the western sill, which is bounded by a system of
shallow (less than 50 m) banks: Skerki and Adventure banks, Empedocle seamount and
Pinne-Nameless bank.

Skerki bank is a broad underwater ridge, which is about sixty miles from the island of
Marettimo, essentially in the middle of the Strait of Sicily, between Sicily and Tunisia. In
general, it consists of four ascents, each with a different name: on SW is the Hacate patch,
which extends for about 3 miles in a succession of ridges and canyons and vast expanses of
submerged boulders; follows, in the middle, the Keith reef, also called “point zero” as it has a
rock that reaches 0.30 m from the surface, extends for about 2 miles between 10 and 20
meters characterized by cliffs and boulders that follow one another to form ridges. To the
north west of Keith rises from the bottom the Biddlecombe plateau, less jagged then other
rises but with gradients of more than 15 meters that fall into the deep. On the north east,
closer to the Sicily, is the Silvia knoll, an extended plateau of white rock; over the plateau,
when the depths go deeper, there are a series of long ridges, up to 1 mile long, with peaks
between 18 and 24 meters (Fig. 3).

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