Cyclic triaxial tests on frozen sand

Strain-controlled cyclic triaxial tests were performed on a one-size silica (Ottawa) sand artificially frozen into 71.1-mm-diameter cylindrical samples. Ice-saturated samples with three different sand contents were tested under the following conditions: axial strains ranging from 3 × 10⁻³ to 3 X 10⁻²%, confining pressures from zero to 1.378 MPa, frequencies of 0.05–5.0 cps and temperatures from −1 to −10 °C.

Test equipment included (1) an MTS electrohydraulic closed-loop testing system which applies the load to the sample, (2) a triaxial cell completely immersed in a low-temperature coolant for temperature control, (3) a refrigeration unit for control of the coolant temperature and constant coolant circulation and (4) measuring devices including an LVDT and load cell, together with recording devices such as a digital multimeter, an oscilloscope, a strip-chart recorder and a minicomputer.

Test results indicate that the dynamic Young's modulus increases with increasing frequency, confining pressure and sand content, but decreases with increasing strain and temperature. The damping ratio decreases with increasing frequency, sand content and lower temperatures. The influence of confining pressures and axial strain on the damping ratio are less explicit for the ranges considered. The experimental results are compared with data from other sources.     

Effects of stem density upon sediment retention by salt marsh cord grass,Spartina alterniflora loisel

A laboratory experiment was conducted to determine whether retention of waterborne sand by salt marsh cordgrass, Spartina alterniflora Loisel, is directly related to the number of stems per unit area. Waves generated in a trough washed over a sloping beach planted with S. alterniflora sprigs: a range of stem densities (0–108 stems/m²) was examined in separate trials. The amount of sand accumulated after 60 waves is a positive nonlinear function of stem density. The greatest accretion coincided with the highest stem density tested. Shape of the beach profile was also strongly influenced by the number of stems per m².     

An automatic data processing system for storage and manipulation of life history,catch, and angler effort data

Responding to a need created by voluminous collections of fish life history, catch and angler effort information, a computerized information management system was developed at the National Marine Fisheries Service laboratory in Beaufort, N.C. for use on an IBM Model 360/65 Computing System. The management system incorporates sequential data storage on disks, analytic programs written in IBM FORTRAN IV, and editing/updating programs written in American National Standard COBOL. The file creation procedure utilizes single or multiple card entry records to generate a single master record. Analytic programs generate arrays displaying fish weights and simple statistics, length-frequency distributions, catch curves, back-calculated fish lengths per annulus, back-calculated length frequency distributions, percentages sexually mature, reproductive condition, age at sexual maturity (using gonad index), occurrence and abundance.     

The isotopic composition of carbon in the Alberta oil sand

The carbon isotopic ratios obtained from Athabasca bitumen, asphaltene and maltene have the same value $\text{δ}{}^{13}\text{C}\text{= ?29.6}\text{per ml}$. The corresponding values in the Cold Lake deposits are ?30.6, ?30.0 and ?31.6 per ml. The ratios determined for methane collected from the oil sand and its fractions are about 15 per ml lower than the above values. It appears that the Athabasca and Cold Lake Reservoirs have similar histories.     

The Nazca Group of south-central Peru: Age,source, and regional volcanic and tectonic significance

The Nazca Group, exposed east of Nazca, Peru, consists of a lower part composed of conglomerate and finer-grained clastic strata and an upper part made up of at least seven ash-flow sheets (cooling units or ignimbrites), collectively known as the Nazca Tuff. These tuffs were erupted between about 22 and 18 m.y. ago from a vent area in the vicinity of Pampa Galeras now marked by a collapse caldera. The early Miocene age of the Nazca Tuff provides additional evidence for a major pulse of largely pyroclastic felsic volcanism throughout the central Andes during the early Miocene. Recognition of the Pampa Galeras caldera supports the idea that many of these rocks were erupted from vent areas of the collapse-caldera type located near the eastern margin of the Coastal batholith.The Nazca Group overlies a major erosional surface cut on the Coastal batholith and its envelope that can be traced southward to the Chilean border. This surface is a continuation of the post-Incaic erosional surface to the north, which is overlain by conglomerate and radiometrically dated volcanic rock of late Eocene age. The post-Incaic surface therefore represents a major episode of regional uplift and pedimentation that followed early Tertiary orogeny. The absence of volcanic rocks of late Eocene/early Oligocene age overlying the Coastal batholith near Nazca and in southern Peru may reflect a general absence of post-Incaic volcanism in this portion of the Andes possibly related to differences in the angle of subduction and/or restriction of volcanic and volcaniclastic rocks of this age to depositional basins east of the batholith.     

Seafloor spreading history of the Agulhas Basin

Data gathered by recent “Islas Orcadas” cruises reveal the seafloor spreading pattern for a region south of the Agulhas/Falkland fracture zone system. The presence of a magnetic anomaly bight about the Agulhas Plateau indicates that the Agulhas Plateau may have developed at the site of a tectonic plate triple junction during the Late Cretaceous. A westward jump in the seafloor spreading center during the Late Maestrichtian (anomaly 34?31) reduced the offset across the Falkland/Agulhas fracture zone system and resulted in the formation of two conjugate aseismic ridges here described as the Meteor and Islas Orcadas Rises. The magnetic lineation pattern in the Agulhas Basin suggests that a tectonic plate (Malvinas Plate) existed during Campanian to Maestrichtian times. Relative rates of motion are calculated for Antarctica, South America, and Africa for the Late Cretaceous.     

On the behaviour of dumped dredger spoil

Observations carried out on the dredger dumping grounds at Lowestoft have shown that fine particulate dredger spoil consists of two phases, one semi-fluid and the other a solid. Once introduced into the marine environment these two phases behave differently. The solid phase falls directly to the bed where it forms a persistent deposit with a localized effect while the semifluid phase is carried by the prevailing currents in the form of a turbid cloud. The possible significance of this twin-phase behaviour is discussed.     

Employment in retailing: A case study of employment in suburban shopping centres

There have been many studies of the retail industry in recent years, and of the impact that retailing has had on the spatial arrangement of urban areas and on consumer behaviour. Little attention has been paid, however, to employment in retailing, which is disturbing in view of its growing importance and its rapidly changing nature and composition. This paper examines the nature of the broad structural changes within the industry, and investigates their spatial consequences through a case study of employment generation within a system of suburban retail centres in Canberra, Australia. It is shown that the evolution of suburban centres, particularly those of a regional variety, has had an important and enriching impact on the suburban labour market. The regional centres are also seen to be the focus of the major structural employment changes currently affecting the retail industry. This has some important implications for urban planning.