Platform Off Research Articles

Pre-Late Weichselian submerged rock platforms off Stonehaven

The existence of rock platforms around Scotland which pre-date the Late Weichselian (equivalent to the Late Devensian) glaciation is becoming increasingly apparent ([Sissons 1981][1]; [Browne and McMillan 1984][2]). This note describes the occurrence of three such platforms in the offshore area around Stonehaven, on the east coast of Scotland. The evidence for the platforms is based on the interpretation of seismic lines as shown in Plate 1. The platforms have been numbered 1 to 3 for reference, and their areal extent is indicated in Figure 1. These features appear to be unique to this area; however, work is in progress to find equivalent features elsewhere. The platforms have a step-like appearance and can be considered to be horizontal in profile as they slope gently away from the coast with apparent gradients of 0.5 to 2 m per kilometre. Platforms 1 and 2 appear to trend sub-parallel to the present shoreline; the trend of platform 3 is uncertain. Platform 1 occurs at a depth of 30 m below sea level and is over 1 km in width. The nature and location of the shoreward termination of this platform is uncertain because the seismic data do not extend inshore. Platform 2 occurs at a depth of 45 to 50 m and is about 4.5 km wide. Both platforms are cut into Devonian strata and are overlain by a discontinuous veneer of till and lithic-dominated littoral sands and gravels derived from the till. Platform 3 is the broadest platform extending to 7.5 km, . . . [1]: #ref-2 [2]: #ref-1

Extensive Submarine Lithification in a Cave in the Belize Barrier Reef Platform

ABSTRACT Extensive deposits of submarine cements discovered in a submerged Pleistocene cave in the outer barrier-reef platform off Belize, Central America, occur in an unusual setting--on and within countless calcareous projections formed by serpulid worms on the ceiling of the cave. The cements are predominantly dense submicrocrystalline and microcrystalline to porous chalky or submicrosucrosic magnesium calcite (approximately 15 mole % MgCO3), and they contain minor amounts of acicular aragonite, which generally forms a lining inside the aragonitic serpulid tubes. Radiocarbon dates, three-year artificial substrate experiments, and evidence of the ceiling's original relief indicate a low rate of accumulation for the serpulid-cement projections. The characteristic 20-60 µm peloidal texture associated with magnesium calcite submarine cements is well developed here and there within the projections. These peloids are physiochemical precipitates, having formed during the development of the submarine cement deposits, which accumulated preferentially on substrates that have a slow rate of accumulation and that experience little or no disturbance of their sediment cover. Artificial substrates placed on the ceiling of the cave for three years revealed that the initial stage of precipitation of magnesium calcite from seawater is in the form of a submicrocrystalline magnesium calcite dust.

Use of offshore mooring platform for sea wave motion analysis

An offshore mooring platform for supertankers may often turn out to be an ideal solution for the problem of installing a meteorological station. Its location may be particularly desirable for the purpose of recording and analysing sea wave motion in deep water or in the intermediate zone between shallow and deep water. We are reporting the preliminary results obtained through the operation of a subsurface sensor at the mooring platform off the harbour of Genoa.

The Effect of Depth on Survival and Growth of Oysters in Suspension Culture from a Petroleum Platform Off the Texas Coast

The effect of depth on oysters in suspension culture from a petroleum platform off the Texas coast was monitored for 20 months. Growth and condition was similar for adult oysters cultured at five levels down to 8 m. Oysters had a growth rate of 1.2 mm (level 3) to 1.4 mm (level 1) per month,representing an increase in length of 94% to 150% for the 20 months. The condition was best in June 1973 after five months placement offshore (condition index of 14.8, 15.5, 14.7, 13.5 and 13.2 for levels 1 through 5, respectively). The condition was lowest in June 1974 (2.2, 2.1, 1.3, 1.4 and 1 .5 for levels 1 through 5, respectively). Ninety oysters died during the experimental period. Sixty-three percent were trom the upper two levels. One hundred forty-five oysters disappeared. Fifty-eight percent were from the bottom two levels. Most oysters disappeared in February 1974 (47% of all disappearances).

X ray probes in action

Ariel 5, the British designed x ray satellite, was launched successfully from the San Marco platform off the Kenyan coast in October, atop a NASA Scout rocket. The mission commenced just eight days after the equally successful flight of a Skylark rocket carrying x ray instruments.

Interaction of genetic processes in holocene reefs off North Eleuthera Island, Bahamas

The inner shelf platform off North Eleuthera consists of a series of terraces at 6 m, 8 m, 20 m, and 35 m depth, respectively. The boundary between 6 and 8 m terraces is marked by a near continuous reef ridge, landward and seaward of which isolated reef structures are found. Reefs are aggregates of pillar structures, which in turn are composed of columnar, club-shaped or mushroom-shaped pillars of corals. The dominant primary framebuilder above 3 m depth isAcropora palmata; below corals of the generaMontastrea andDiploria, Porites astreoides andP. porites also contribute to the frame, as does the hydrozoanMillepora. The secondary framebuilders start developing and changing the shape of the frame as soon as they find suitable substrates; most important are coralline red algae, which encrust internal and external surfaces, but also may fuse the components of the frame; other organisms just add to the frame. In contrast boring and rasping organisms destroy the frame. Constructing or destructing organisms were found living on every surface, external or internal, accreting or diminishing.

Studies of turbulent diffusion of dye patches in the ocean

Experimental data on diffusion of dye patches in the sea obtained in near shore areas, including estuaries of the coast of the Gulf of Mexico are analyzed and compared with theories of turbulent diffusion. Change of radius of dye patches with time is explained from theories of G. I. Taylor and others. Detailed structure of diffusion pattern is discussed by use of the data obtained at a platform off Panama City, Florida. Particularly the speed of diffusion, vertical eddy accompanying the bottom layer of dye patches and strange pattern of edges of patches are discussed in relation to the environmental, hydrodynamical conditions such as vertical stability, mean velocity, and sea surface conditions.