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Falling model on the planktonic diatoms
782
Oceanographic Abstracts
The palaeomagnetic data can therefore be used to reconstruct the northern hemisphere in pre-Triassic times: Europe and North America were closer together and in low latitudes. Comparison between the Precambrian of the western United States and the Keweenawan system appears to provide evidence of displacements within North America before the world-wide orogenic
epoch of 1000My ago.
Rtn~com,~ S. K., 1965. Changes in the convection pattern in the Earth's mantle and continental drift: evidence for a cold origin of the Earth. Phil. Trans. R. Sot., A, 258 (1088): 228-251. Continental displacements of thousands of kiiometres point to flow patterns in the mantle of similar dimensions. A.~ creep depends exponentially on temperature and as it is known that the temperature of the crust increases rapidly with depth, we can in this context suppose the mantle to have a sharp transition between a rigid crust and a fluid mantle at 50 to 100 km depth, Recently the coefficients of the tesseral harmonies of the geopotential from satellite observations have been determined. These departures from hydrostatic equilibrium seem to be caused by flow in the mantle, for from these coefficients can be computed the tractions exerted by the flow on the crust, assuming NavierStokes's equations, and the resulting pattern accords well with the worid-wide tectonic featui'es. Rising flow is associated with the Fast Pacific Ocean Rise, the Mid-Atlantic Ridge and the Mid-Indian Ocean Rise. Descending currents coincide with the Andes, the Alps and the Japan trench. The strong fifth harmonic in the satellite gravity data suggests that a flow pattern of this degree is at present establishing itself. On the other hand, continental reconstructions prior to Wegenerian drift suggest the presence of a strong fourth harmonic in the flow pattern. The theory of marginal stability in thermal convection, disctts~d by S. Chandrasekhar, shows that convection in a spherical shell under a uniform radial gravitational field gives the critical ratio of the radii of the inner to outer surfaces (-,/) at which the fifth order is more likely to develop than the fourth as 0-54. The closeness of this value of ,i to the present one of 0.55 provides a clue to the most puzzling feature of continental drift; that it should have occurred in the last 5 ~ of the Earth's history. H. C. Urey suggested that, on the accretion theory of the Earth's origin, the separation of iron towards the centre might have gradually occurred through the Earth's life. A growth of the core from 0.54 to 0-55 in the last 100-200 My does not conflict with the known rate of change in the length of the day. This explanation of the flow in terms of convection and changes in the degree of the flow pattern as a result of growth of the core implies earlier epochs of continental displacements, which are identified with peaks in the histograms of radiometric ages in the various continents. The law of growth of the core, so obtained, explains why so few rocks of greater age than 3000 My are found.
SACIC.k-I~WILLIAMM., 1965. Deposition rates by the protactinium method. Narragansett Mar. Lab., Univ. Rhode lsland, Occ. Publ., No. 3 : 29-40. If future work proves conclusively that ionium sometimes migrates upwards in deep,sea sediments and that all dating methods based on the distribution of unsupported ionium are unreliable, then the protactinium method may provide a reliable alternative. Although the specific activity of protactinium-231 in sediments is v e ~ low and the separation of protactinium carrier-free is relatively difficult, this paper shows that Pa ~I may be determined routinely and seemingly with good precision. Ages by the protactinium method agree within 30 ~. of radiocarbon ages on the four cores analyzed in this study. SAKAMO'rOIcm'rxRo, 1964. Falling model on the planktonic diatoms. Rep. Fac. Fish., Pref. Unio. Mie., 5 (1): 33-.49. Physical models of diatoms were schematically constructed as an attempt to study the falling velocity of diatoms and the density in-situ, and the dimensions related to their shape were also discussed in some detail. The model of a diatom cell has three elements: the shell, oil particles and cell sap. The condition of a diatom cell required for it to stay in neutral equilibrium was discussed on the assumption that the densities of these three constituents are ds = 2.7, do = 0.925, ell = d (in-situ density of environmental water) : S . X -1 ----(d -- 0.925) (2.7 -- d)-~ volume of shell where, S = volume of cell volume of oil particles X= volume of cell S+X
Oceanographic Abstracts
783
Stokes" law (for the velocity of a falling particle) may be transformed into the following equation. Vel ----47.08.___.88.{S.(1700 -- atD) -- X'(75 ÷ a t D ) ) . D_.S*"cm/dav I~ 10z K " where, i~ = Viscosity in millipoise.
cl = 1 + c~to/lOZ D = 1.24 ax/I,' = etTective diameter in micron. K = Resistance coefficient due to the shape. The maximum falling velocity which occurs at dp rna.~ is obtained from : 47.0S8 (I700 -- C~tD) S'D: S'D: 1.502.v.S-I.'*-:~ Vel max . . . . . . v. - cm/day I• 103 K K K A practical formula in the time required for centrifuging is : 89.3 T --- ~ minutes where n : Rotation number in 103 revolutions/minnute. The shapes of planktonic diatoms, which vary from that of a needle to that of a membrane was tentatively represented by a disc. A study was then made as to the relationship between changes in shape and the surface ratio, or the section ratios. This relationship and the coefficient of resistance due to shape (K) needs further confirmation based on new experiments. In a quantitative study o f mieroplankton from water-samples, it is necessary to find out a sure method for concentration based on the size of the organisms. Both the settling and centrifuge methods are not suitable for such a study. SCHAPJRA SERGIU, 1964. Marine electrical fishing. Boll. Pesca, Pisclcolt. IdrobioL, n.s. 19 (2): 273-286. The two most important problems to be considered if marine electrical fishing is to be effective, are the creation of suitable electrical fields in the water to grade the fish, and the construction of efficient impulse generators. The form and dimensions of electrodes, and the reaction o f the fishes to different kinds o f electrical currents were first studied. By using impulse generators, which produce pulse currents of very great amplitude and short duration, electrical fishing can be c a r d e d out inexpensively. Practical applications are given to determine the magnitude a n d width of the pulses. Further, the electrical parameters o f the pulse generator are determined in agreement with the requirements of the computed fields. SCHEt.L I. I., 1965. The origin and possible prediction of the fluctuations in the Peru Current and upwelling. J. eeophys. Res., 70 (22): 5529-5540. A n analysis was made of sea surface temperature anomalies for 14 stations along the west coast of South America, including one immediately north of the equator, in relation to the pressure distribution representing the westerlies and their convergence in the eastern South Pacific between 35 and 50"S and also the southerlies and southeasterlies along the coast north of 40°S. It appears that weaker westerlies and their marked convergence, linked to weaker southerlies and southeasterlies, as associated with higher sea surface temperatures along the coast and with a weaker Peru current and a weaker upwelling. It further appears that weaker westerlies and their marked convergence, linked to weaker southerlies and southeasterlies during the M a r c h - N o v e m b e r period are associated with higher sea surface temperatures during the following December-February quarter, or El Nifio season. If this association is confirmed, it should be possible to predict El Nifio. ScHtrrz DOr~At.D F. and KARL K. TUP~.EKIAN,.1965. The distribution o f cobalt, nickel, and silver in ocean water profiles around Pacific Antarctica. J. geophys. Res., 70 (22): 5519-5528. The concentrations of cobalt, nickel, and silver, determined by neutron activation analysis, are systematically lower in the east Pacific sector of the Antarctic Ocean relative to other oceanic areas. This is indicated by two traverses between 70-'S and 54°S at I15°W and about 90:W. Transport o f cobalt, nickel, and silver from the Pacific Ocean to the Atlantic Ocean via the Drake Passage is thus minimal. Calculations based on the silver concentration in Pacific and Antarctic waters and Antarctic sediments indicate that a flow rate 1% of that predicted for the transport of Pacific deep water is consistent with the data. The dissolving of glacial flour may be responsible for the relatively high concentrations of cobalt and nickel encountered at the closest approach to the Antarctic continent. SCOTT E. O. G., 1965. Obse~'ations on Tasmanian fishes XIII. Papers andProc., R. Soe., Tasmania, 99: 53-65. Gymnothorax leecote sp. nov. (Muraenidae), the first member o f the family recorded from Tasmanian waters, is described and figured. Other additions to the State list are Petraltes heptaeolus Ogilby, 1865 (Clinidae), Ophiclinus gabrieli Waite, 1906 (Ophielinidae), Callogobius hassehii (Bleeker), 1851 (Gobiidae), Tetraodon firmamentum Temminck & Schlegel. 1850 (Tetraodontidae). Miscellaneous observations are made on Muraenichthys tasmaniensis McCulloch, 1911 (Echelidae) (description o f a specimen from Green's Beach, Devon) : Urocampus carinirostris Castelnau, 1872
Oceanographic Abstracts
The palaeomagnetic data can therefore be used to reconstruct the northern hemisphere in pre-Triassic times: Europe and North America were closer together and in low latitudes. Comparison between the Precambrian of the western United States and the Keweenawan system appears to provide evidence of displacements within North America before the world-wide orogenic
epoch of 1000My ago.
Rtn~com,~ S. K., 1965. Changes in the convection pattern in the Earth's mantle and continental drift: evidence for a cold origin of the Earth. Phil. Trans. R. Sot., A, 258 (1088): 228-251. Continental displacements of thousands of kiiometres point to flow patterns in the mantle of similar dimensions. A.~ creep depends exponentially on temperature and as it is known that the temperature of the crust increases rapidly with depth, we can in this context suppose the mantle to have a sharp transition between a rigid crust and a fluid mantle at 50 to 100 km depth, Recently the coefficients of the tesseral harmonies of the geopotential from satellite observations have been determined. These departures from hydrostatic equilibrium seem to be caused by flow in the mantle, for from these coefficients can be computed the tractions exerted by the flow on the crust, assuming NavierStokes's equations, and the resulting pattern accords well with the worid-wide tectonic featui'es. Rising flow is associated with the Fast Pacific Ocean Rise, the Mid-Atlantic Ridge and the Mid-Indian Ocean Rise. Descending currents coincide with the Andes, the Alps and the Japan trench. The strong fifth harmonic in the satellite gravity data suggests that a flow pattern of this degree is at present establishing itself. On the other hand, continental reconstructions prior to Wegenerian drift suggest the presence of a strong fourth harmonic in the flow pattern. The theory of marginal stability in thermal convection, disctts~d by S. Chandrasekhar, shows that convection in a spherical shell under a uniform radial gravitational field gives the critical ratio of the radii of the inner to outer surfaces (-,/) at which the fifth order is more likely to develop than the fourth as 0-54. The closeness of this value of ,i to the present one of 0.55 provides a clue to the most puzzling feature of continental drift; that it should have occurred in the last 5 ~ of the Earth's history. H. C. Urey suggested that, on the accretion theory of the Earth's origin, the separation of iron towards the centre might have gradually occurred through the Earth's life. A growth of the core from 0.54 to 0-55 in the last 100-200 My does not conflict with the known rate of change in the length of the day. This explanation of the flow in terms of convection and changes in the degree of the flow pattern as a result of growth of the core implies earlier epochs of continental displacements, which are identified with peaks in the histograms of radiometric ages in the various continents. The law of growth of the core, so obtained, explains why so few rocks of greater age than 3000 My are found.
SACIC.k-I~WILLIAMM., 1965. Deposition rates by the protactinium method. Narragansett Mar. Lab., Univ. Rhode lsland, Occ. Publ., No. 3 : 29-40. If future work proves conclusively that ionium sometimes migrates upwards in deep,sea sediments and that all dating methods based on the distribution of unsupported ionium are unreliable, then the protactinium method may provide a reliable alternative. Although the specific activity of protactinium-231 in sediments is v e ~ low and the separation of protactinium carrier-free is relatively difficult, this paper shows that Pa ~I may be determined routinely and seemingly with good precision. Ages by the protactinium method agree within 30 ~. of radiocarbon ages on the four cores analyzed in this study. SAKAMO'rOIcm'rxRo, 1964. Falling model on the planktonic diatoms. Rep. Fac. Fish., Pref. Unio. Mie., 5 (1): 33-.49. Physical models of diatoms were schematically constructed as an attempt to study the falling velocity of diatoms and the density in-situ, and the dimensions related to their shape were also discussed in some detail. The model of a diatom cell has three elements: the shell, oil particles and cell sap. The condition of a diatom cell required for it to stay in neutral equilibrium was discussed on the assumption that the densities of these three constituents are ds = 2.7, do = 0.925, ell = d (in-situ density of environmental water) : S . X -1 ----(d -- 0.925) (2.7 -- d)-~ volume of shell where, S = volume of cell volume of oil particles X= volume of cell S+X
Oceanographic Abstracts
783
Stokes" law (for the velocity of a falling particle) may be transformed into the following equation. Vel ----47.08.___.88.{S.(1700 -- atD) -- X'(75 ÷ a t D ) ) . D_.S*"cm/dav I~ 10z K " where, i~ = Viscosity in millipoise.
cl = 1 + c~to/lOZ D = 1.24 ax/I,' = etTective diameter in micron. K = Resistance coefficient due to the shape. The maximum falling velocity which occurs at dp rna.~ is obtained from : 47.0S8 (I700 -- C~tD) S'D: S'D: 1.502.v.S-I.'*-:~ Vel max . . . . . . v. - cm/day I• 103 K K K A practical formula in the time required for centrifuging is : 89.3 T --- ~ minutes where n : Rotation number in 103 revolutions/minnute. The shapes of planktonic diatoms, which vary from that of a needle to that of a membrane was tentatively represented by a disc. A study was then made as to the relationship between changes in shape and the surface ratio, or the section ratios. This relationship and the coefficient of resistance due to shape (K) needs further confirmation based on new experiments. In a quantitative study o f mieroplankton from water-samples, it is necessary to find out a sure method for concentration based on the size of the organisms. Both the settling and centrifuge methods are not suitable for such a study. SCHAPJRA SERGIU, 1964. Marine electrical fishing. Boll. Pesca, Pisclcolt. IdrobioL, n.s. 19 (2): 273-286. The two most important problems to be considered if marine electrical fishing is to be effective, are the creation of suitable electrical fields in the water to grade the fish, and the construction of efficient impulse generators. The form and dimensions of electrodes, and the reaction o f the fishes to different kinds o f electrical currents were first studied. By using impulse generators, which produce pulse currents of very great amplitude and short duration, electrical fishing can be c a r d e d out inexpensively. Practical applications are given to determine the magnitude a n d width of the pulses. Further, the electrical parameters o f the pulse generator are determined in agreement with the requirements of the computed fields. SCHEt.L I. I., 1965. The origin and possible prediction of the fluctuations in the Peru Current and upwelling. J. eeophys. Res., 70 (22): 5529-5540. A n analysis was made of sea surface temperature anomalies for 14 stations along the west coast of South America, including one immediately north of the equator, in relation to the pressure distribution representing the westerlies and their convergence in the eastern South Pacific between 35 and 50"S and also the southerlies and southeasterlies along the coast north of 40°S. It appears that weaker westerlies and their marked convergence, linked to weaker southerlies and southeasterlies, as associated with higher sea surface temperatures along the coast and with a weaker Peru current and a weaker upwelling. It further appears that weaker westerlies and their marked convergence, linked to weaker southerlies and southeasterlies during the M a r c h - N o v e m b e r period are associated with higher sea surface temperatures during the following December-February quarter, or El Nifio season. If this association is confirmed, it should be possible to predict El Nifio. ScHtrrz DOr~At.D F. and KARL K. TUP~.EKIAN,.1965. The distribution o f cobalt, nickel, and silver in ocean water profiles around Pacific Antarctica. J. geophys. Res., 70 (22): 5519-5528. The concentrations of cobalt, nickel, and silver, determined by neutron activation analysis, are systematically lower in the east Pacific sector of the Antarctic Ocean relative to other oceanic areas. This is indicated by two traverses between 70-'S and 54°S at I15°W and about 90:W. Transport o f cobalt, nickel, and silver from the Pacific Ocean to the Atlantic Ocean via the Drake Passage is thus minimal. Calculations based on the silver concentration in Pacific and Antarctic waters and Antarctic sediments indicate that a flow rate 1% of that predicted for the transport of Pacific deep water is consistent with the data. The dissolving of glacial flour may be responsible for the relatively high concentrations of cobalt and nickel encountered at the closest approach to the Antarctic continent. SCOTT E. O. G., 1965. Obse~'ations on Tasmanian fishes XIII. Papers andProc., R. Soe., Tasmania, 99: 53-65. Gymnothorax leecote sp. nov. (Muraenidae), the first member o f the family recorded from Tasmanian waters, is described and figured. Other additions to the State list are Petraltes heptaeolus Ogilby, 1865 (Clinidae), Ophiclinus gabrieli Waite, 1906 (Ophielinidae), Callogobius hassehii (Bleeker), 1851 (Gobiidae), Tetraodon firmamentum Temminck & Schlegel. 1850 (Tetraodontidae). Miscellaneous observations are made on Muraenichthys tasmaniensis McCulloch, 1911 (Echelidae) (description o f a specimen from Green's Beach, Devon) : Urocampus carinirostris Castelnau, 1872