ALBERT

Description: The submarine Mascarene Plateau, lying east and northeast of Madagascar in the west central Indian Ocean, extends as a faulted composite arc for 2300 km, from the Precambrian granitic “micro-continent” of Seychelles Bank southward through the coral–reef–capped volcanic structures (?) of Saya de Malha, Nazareth, and Cargados Carajos banks to the faulted Tertiary–Quaternary oceanic volcanic island Mauritius. Locally the aseismic plateau is buttressed by spurs, is steep-sided and angular in plan, or is extended, disrupted, or offset by cross–faulting. Other major structural elements in a sector centered on the Mascarene Plateau are: (1) the seismically active Mid-Indian Ocean Ridge and rift zone (including that portion known as the Carlsberg Ridge) between the equator and its bifurcation near 23°S.; (2) the angular and faulted Amirante Trench lying between Seychelles Bank and the Madagascar-Farquhar complex; (3) the east–west late Tertiary–Pleistocene Rodriguez Ridge and its possible extension eastward as a fracture zone offsetting the Mid-Indian Ocean Ridge; (4) the Mauritius Trench, a 1400-km border deep-trending southwest from east of Mauritius to 28°S., 51°E. Irregular topography, attributed to volcanism and block faulting, is strikingly developed southeast of the intersection of Rodriguez Ridge with the Mascarene Plateau. Here linear, slightly sedimented deeps and narrow ridges lie subparallel to Mauritius Trench and to the southwest branch of the Mid-Indian Ocean Ridge. Except in the northwest sector where northwest and north trends lie within the Agalega–Seychelles–Amirante–Owen Fracture Zone complex, the dominant topographic lineations are northeast to east–northeast. These are displayed by large features such as fractures offsetting the mid-oceanic ridge (for example, Vema Trench), the Mauritius Trench and the linear topography southeast of Mauritius, the apparent offsets of the southern half of the Mascarene Plateau, spurs on the west flank of the mid-oceanic ridge, and the smaller ridges protruding; from the sedimented rise and abyssal plain between Tromelin and the Mascarene Plateau. Offsets of the Mascarene Plateau along northeast-trending faults-occurred in Tertiary time as adjustments accompanying formation of the Mascarene Basin. Activity on several of these faults has continued where they intersect the crestal portions of the mid-oceanic ridge system, but growth of the exceedingly rough, ridge in this region is primarily by addition of igneous material along its axis.

Description: The drilling vesselSubmarex of Global Marine was used to drill and core sediments to a depth of 56.4 m on the Nicaragua Rise, between Walton Bank and Jamaica, in 610 m of water. Seismic reflection profiles revealed thick accumulations of layered sediments with some fossil reefs. The sediments consist of undisturbed layers rich in planktonic microfossils alternating with turbidite layers. Absence of older coccoliths indicates that the redeposited material was not appreciably older than the time of redeposition, and oxygen isotopic analysis of benthonic elements shows that this material was derived from a depth not much shallower. The lower portion of the cored section correlates with the Manchioneal Formation of Jamaica. Taxonornic analysis of the calcareous nannoplankton indicates that the level at 2354 cm correlates with the midportions of the eastern equatorial Pacific cores 58 and 62; with the “Nebraskan-Aftonian” boundary of the Gulf Coast; and with the appearance of Hyalinea baltica at Le Castella, southern Italy. This level, therefore, represents the Plio-Pleistocene boundary as officially designated, and an age of about 700,000 years is estimated for the bou ndary. Oxygen isotopic analysis shows important oscillations, with a full glacial-interglacial amplitude, occurring both above and below the Plio-Pleistocene boundary.

Description: Facies trends were developed for San Pedro Bay, California, based upon 44 well-distributed stations. The area of investigation extends from the shore out to depths of 176 m, a distance of about 20 km, and spans a distance along the shelf of about 25 km. Sediments of the bay are mostly detrital sands along the shore line, silty sands on the shelf, and silts and silty sands on the slope off the edge of the shelf; residual and relict sediments (sands and silty sands) occupy a central region, contributing to more complex sedimentary patterns. Values for calcium carbonate and nitrogen are highest along the outer edge of the shelf and in the upper bathyal zone. Polychaetes dominate the megafauna; foraminifera dominate the microfauna. Forammiferal abundance and species diversity are greatest in outer areas of the shelf and in the upper bathyal zone; live/dead ratios are highest in central and inner shelf areas; live foraminifera are about three times as abundant in the upper bathyal zone as on the shelf. Calcareous perforate foraminifera dominate both dead and live assemblages throughout the area. Planktonic/benthic ratios are highest in the upper bathyal region; values for planktonic specimens per gram increase 20–100 times from the shelf into the bathyal zone. In the upper 10 m of the water column, phosphate and plankton cells per liter attain highest values in the central and inner shelf areas; however, in the lower 10 m of the water column, there is a general increase in phosphate values away from shore. Benthic foraminiferal populations may be grouped into inner shelf Buliminella elegantissima (d'Orbigny), central and outer shelf Nonionella-Trochammina, and upper bathyal Bolivina acuminata Natland groups. Hopkinsina pacifica Cushman is diagnostic of the general harbor region; Bulimina marginata denudata Cushman and Parker occurs in both the harbor and in the outer shelf and upper bathyal zones. The edge of the shelf, a structural trend, is defined by the boundary zone between the Nonionella and Bolivina acuminata Natland faunal groups. Similar structural trends may be indicated in the California marine Miocene by boundary zones between analogous faunal groups.

Description: The microtopography of the continental shelf in five areas between Nova Scotia and New York was investigated with side-scanning sonar. The results were checked against those previously obtained by conventional methods in all areas and against later visual observations of the bottom from a research submersible vessel in two areas. Side-scanning sonar proved to be an ideal device for learning the distribution and relationships of rock, boulder, and sand bottoms and for measuring the patterns and trends of several sizes of sand waves and of large ripple marks.

Description: Der Strommesser registriert selbsttätig photographisch Stromrichtung und Stromgeschwindigkeit im Meere, und zwar bis zu einer Meßdauer von vier Wochen in Abständen von fünf Minuten. Er besitzt Eigenauftrieb und ist deshalb einfach zu verankern. Er kann bis Meßtiefen von 50 m ausgelegt werden. Dieser neue Strommesser nutzt die Vorzüge des Schaufelradstrommessers von H. Rauschelbach, der sich seit 25 Jahrerr in vielen hundert Auslegungen bewährt hat. Er vermeidet einen wesentlichen Nachteil dieses Gerätes, der besonders in gezeitenstromarmen Meeren wie der Ostsee ins Gewicht fällt, nämlich die hohe Anlaufgeschwindigkeit. Das neue Gerät ist ein Propellerstrommesser, der bei nur 2,5 cm/sec Stromgeschwindigkeit anspringt. Selbst in Bodennähe randlicher Meeresbuchten wie der Eckernförder Bucht konnten brauchbare Strommessungen über längere Zeiträume erzielt werden.

Description: Die Schlei, eine Förde der schleswig-holsteinischen Ostseeküste, wird als ein stark durch Abwässer belastetes Brackwassergebiet hydrographisch und biologisch untersucht. Die hydrographischen Bedingungen lassen zusammen mit den nur unwesentlichen Strömungen keinen ausreichenden Abbau der übermäßigen Eutrophierungserscheinungen zu. Die früher reiche tierische und pflanzliche Bodenbesiedlung ist besonders in der inneren Schlei durch Mudablagerungen auf weite Strecken vernichtet. Die Massenentwicklungen verhältnismäßig weniger Arten bestimmen im Plankton wie Benthos hier das Bild. Besonders wird auf die Ciliatenbesiedlung eingegangen, die unter dem Einfluß der verschiedenen Faktoren wie Bodenbeschaffenheit, Salzgehalt, Eutrophierung, Bakteriendichte ein gutes Bild der herrschenden Zustände gibt. Biological investigations, especially of the Ciliate fauna in the polluted water of the SchleiFjord (western Baltic) (Summary): The Schlei, a fjord on the Ballic coast of SchleswigHclstein, is a brackish water area much clogged with sewage. In the present paper it is clwmined hydrographically and biologically. The hydrographical conditions in connection with onlv rninor currents does not permit sufficient decomposition of the excessive eutrophic phenomena in the shallow water. The formerly rich bottom life is, especially in the inner Schlei, widely destroyed by mud deposits. The mass development of comparatively few species determine the picture of plankton as weil as of benthos. Particular stress is laid on the present distribution of ciliates which, undcr the influence of the various factors such as the nature of the bottom, salinity, eutrophic state, density of bacteria, present a good picture of the prevailing condition.

Description: In Vorbereitung der internationalen Untersuchung der Überströmung des Island-Färöer-Rückens, die im Juni 1960 mit 10 Forschungsschiffen stattfinden soll, wurde ein hydrographischer Schnitt Anfang März 1959 von „Anton Dohrn" durchgeführt und Anfang Mai 1959 vollständig wiederholt. Der Schnitt verläuft am SW-Hang des Rückens (Abb. 1). Es zeigt sich, daß in beiden Fällen ein und dasselbe Gebiet von der Überströmung des sehr kalten, verhältnismäßig salzarmen subarktischen Wassers bevorzugt wird, nämlich in 63° N und 10° W, (vgl. Abb. 2, 3, 5 und 6). Der große Temperaturunterschied in den bodennahen Schichten in etwa 550 m, der zwischen den Aufnahmen im März und Mai 1959 vorhanden war und 4°C erreichte (Abb. 4), deutet auf die großen Schwankungen der Überströmung hin. As a preliminary step to the international investigation of the Iceland-Faroe Ridge, which is scheduled to take place in June 1960 with 10 research ships, a hydrographic section was carried out at the beginning of March 1959 from the "Anton Dohrn". It was repeated in full at the beginning of May 1959. The section runs along the southwestern slope of the ridge (fig. 1). The overflow of very cold subarctic water, poor in salinity, took place in the same area in both cases, in 60° N and 10° W (figs. 2, 3, 5 and 6). The high values of temperature-differences near the sea-bottom in about 550 m between March and May 1959 (fig. 4), reach a maximum of 4°C and indicate very great variations in the overflow itself.