Input of river-derived sediment to the New Zealand continental shelf: I. Mass

The input of river-borne sediments to the New Zealand continental shelf has been calculated for all the major rivers and basins in New Zealand. South Island yields 284 ± 40 × 10⁶ tonnes per year of sediment from a land area of 152 977 km² and North Island yields 105 ± 9·4 × 10⁶ tonnes per year from a land area of 114 621 km². Particularly high discharges are noted off the west coast of South Island and east coast of North Island and result in higher offshore sedimentation there. The data are compatible with measured sedimentation rates on the New Zealand continental shelf. The specific sediment yield from South Island is amongst the highest previously recorded.     

Geophysical investigations of buried river valleys around Cardigan Bay

Gravity and seismic surveys over the estuaries of the rivers Dovey, Dysynni, Glaslyn and Mawddach have indicated that the rock floor lies at depths of from 100 to 1,250 ft (30 m to 380 m) below the present surface. The methods of survey and difficulties of interpretation are discussed, and the significance of the results is assessed in conjunction with those already published for the Teifi estuary and with preliminary results obtained by seismic reflection profiling in. Cardigan Bay. It is concluded that all the valleys with the exception of the Glaslyn could have been carved during Pleistocene times, but that the much deeper buried valley of the Glaslyn, extending south of Portmadoc across Morfa Harlech, is probably of earlier origin.     

A laboratory analog study of the surface morphology of lava flows extruded from point and line sources

In laboratory experiments designed to model lava flow processes, liquid polyethylene glycol wax is forced through either a small hole or a long narrow slit onto the base of a tank of cold water, where it spreads laterally while cooling and solidifying at its surface. We observe the surface structure of the flow, and its dependence on the flow rate, thermal conditions and basal roughness. In each case, solidification of a crust during spreading gives rise to a number of different surface morphologies, each of which forms under a restricted range of conditions. The dominant morphologies, referred to as “pillows”, “rifts”, transverse folds, and marginal levees, correspond to features observed on natural lava flows. Results for radial spreading over a rough base and for spreading in two directions from the line source over both smooth and rough bases complement those reported earlier for radial spreading of solidifying wax from a point source on a smooth base. Together they indicate a robust dependence of morphology on the distance from the vent at which solid crust begins to form. This distance is, in turn, determined by the extrusion rate, the rheology of the liquid wax (or magma), the reduced gravity, the magnitude of the surface heat flux, and the amount of cooling required to solidify the flow surface. The results also indicate factors influencing the distribution of crust and its deformation, and may provide a means by which observations of surface morphology can be used to place constraints on the emplacement conditions of lava flows.     

BVI CCD photometry of the distant open star clusters Berkeley 81, Berkeley 99, NGC 6603 and NGC 7044

We present CCD observations for the distant northern open star clusters Berkeley 81, Berkeley 99, NGC 6603 and NGC 7044 in B V I photometric passbands. A total of 9 900 stars have been observed in fields of about 6 × 6 arcmin² of the sky around the clusters. Colour–magnitude diagrams in V , ( B  −  V ) and V , ( V  −  I ) have been generated down to V  = 22 mag and, for the first time, such diagrams have been produced for the clusters Berkeley 81 and Berkeley 99. The data serve as a base for the study of mass functions and for comparison with theoretical models. Analysis of the radial distribution of stellar surface density indicates that the radius values for Berkeley 81, Berkeley 99, NGC 6603 and NGC 7044 are 2.7, 2.8, 2.8 and 2.2 arcmin respectively. By fitting the latest convective core overshooting isochrones to the colour–magnitude diagram and using its morphological features, reddenings, distances and ages of the star clusters have been determined. Broad but well-defined main sequences with stellar evolutionary effects in the brighter stars are clearly visible in colour–magnitude diagrams of all the clusters under study. Some blue stragglers along with well-developed giant branches and red giant clumps are also clearly seen in all of them. The clusters studied here are located at a distance of ∼ 3 kpc, except for Berkeley 99 which is located at a distance of 4.9 kpc. Their linear sizes lie between 3.8 and 8.0 pc; E ( B  −  V ) values range from 0.3 to 1.0 mag, while their ages are between 0.5 and 3.2 Gyr. Thus the star clusters studied here are of intermediate and high age but are compact and distant objects.     

A field study on the acute effects of the dispersant Corexit 9527 on glucose uptake by marine microorganisms

The effects of the dispersant Corexit 9527 and Corexit with crude oil on the rate of glucose uptake and mineralisation were studied in Arctic and Subarctic marine waters and sediments. Essentially all of the 149 water and 95 sediment samples tested displayed decreased glucose uptake rates in the presence of either 15 or 50 ppm Corexit. Depressed uptake rates were observed at concentrations as low as 1 ppm. The mean concentration at which Corexit depressed glucose uptake by 50% was 12 ppm. The effect of Corexit was more pronounced on pelagic than on benthic microbial populations.     

Quantitative estimates of the geology of large regions and their application to mineral-resource assessment

The unit regional value of the mineral resources of a large region may be estimated by accumulating past production records and prorating them over the area of the region. The geological characteristics of a large region is a prime conditioning variable for this purpose. To be useful, however, the geology of a large region must be represented in a standardized form. The “geology,” as here measured, refers to a standardized set of rock types common to the legends in geological maps. By using standardized procedures, the legends of 413 geologic maps at 292 different scales that cover the Earth’s land surface were transformed into a set of 65 three-digit numbers. The set of numbers called the time-petrographic index is associated with the contemporaneous tectonic environments that led to the formation of the rocks and their associated mineral deposits. Application of the time-petrographic index to geologic maps leads to more precise estimates of the mineral-resource values of a large region. Deceased, June 2, 1992     

Indigenous Livelihoods and Art Income: participation,production and returns from woodcarvings in Arnhem Land,north Australia

Participation in the Indigenous visual arts sector provides one of few market opportunities for Indigenous Australians resident on remote Aboriginal lands. In this article we examine the economic factors that influence this market engagement as they relate to woodcarving in the Maningrida region of Arnhem Land. In particular, we look at the factors that affect participation, production and monetary returns using scan and focal sampling, resource accounting and sales data from the regional art centre. Artists were engaged in a range of activities of which art production was the prominent means of productive cash income generation. An artist's residence and also their language community were found to influence the amount of sculpture production undertaken, with artists residing on ‘country’ in the hinterland being more engaged in sculpture production than those living in the township of Maningrida. The annual income earned by an artist for carving was highly variable and a large proportion of woodcarvers also earned income from producing artwork in other media. Capital costs were relatively minor, with travel costs and labour the main input into carving production. Based on the average return for a single woodcarving, $160, we estimate the average hourly return to artists as between $12 and $14. Whilst this figure is relatively low and comparable to the Australian award wage for unskilled labour, the income earned from arts production makes an important contribution to people's livelihoods.