Late Holocene floodplain incision and alluvial fan formation in the central Grampian Highlands,Scotland: chronology,environment and implications

A section cut across an alluvial fan and the underlying floodplain terrace in the central Grampian Highlands provides an unusually complete record of late Holocene events. At ca. 2.7–2.4 cal kyr BP floodplain aggradation was replaced by net floodplain incision. Pollen evidence and charcoal counts provide no evidence for contemporaneous anthropogenic landscape change, and the timing of the transition suggests that it reflects an increase in high-magnitude erosive flood events following overall climatic deterioration. The overlying fan was deposited by torrential hyperconcentrated flows during three brief storm-generated depositional events at ca. 2.2–2.1, 1.9–1.8 and 0.9–0.7 cal kyr BP, separated and succeeded by prolonged periods of stability and peat accumulation. During these three events, a cumulative total of ca. 6750 m³ of sediment was deposited, probably in no more than a few hours over a timescale of two millennia. These findings imply that proposed links between human activity and the development of alluvial fans or debris cones require reassessment, and that different elements of the Holocene alluvial landscape have responded in different ways to the same climatic inputs. Aggregation of dating evidence relating to aggradation or incision of alluvial landforms at different scales therefore may produce misleading results. Copyright © 1999 John Wiley & Sons, Ltd.     

Since turtles cannot talk: what beak movement sensors can tell us about the feeding ecology of neritic loggerhead turtles,Caretta caretta

Understanding the role that consumers play in an ecosystem requires knowledge about food selection and intake rates. However, such basic data are often difficult to obtain, particularly for marine animals that are not easy to observe. To overcome this problem, a beak movement sensor was employed on a free‐ranging loggerhead turtle in a neritic foraging habitat at the Domitian littoral (SW Italy). In combination with gastrointestinal content analysis from six turtles found dead in the same area we sought to identify which beak movement patterns were associated with which prey type, and to quantify the ingestion of the various prey types. Brachyuran crabs (100% occurrence), in particular Liocarcinus vernalis, and small molluscs (66% occurrence) were found most frequently in the stomach and intestine of the turtles. Beak movements revealed average ingestion rates of (mean ± SE) 0.27 ± 0.13 food items per minute and that feeding occurred predominantly during dives >4 m and during early morning and evening. Interestingly, the time spent feeding amounted to only 2.2% of the total observation time, whereas feeding‐associated dives added up to just above 10% of the total time. We thus established that loggerhead turtles in this area are specialised on brachyuran crabs, on which they prey with high success during the short time dedicated to foraging. This information strengthens our knowledge about turtle–prey and turtle–habitat interactions, which are essential data to delineate the role that turtles play in this and similar marine ecosystems. Moreover, since the same area is also intensively used by the regional bottom trawl fishery, our results have important conservation implications, because they clearly show the time of day and water depths for which fishing activity should be regulated to reduce the number of turtles that are currently being incidentally caught in this area.     

Isotopic mapping of groundwater perchlorate plumes

Analyses of stable isotope ratios of chlorine and oxygen in perchlorate can, in some cases, be used for mapping and source identification of groundwater perchlorate plumes. This is demonstrated here for large, intersecting perchlorate plumes in groundwater from a region having extensive groundwater perchlorate contamination and a large population dependent on groundwater resources. The region contains both synthetic perchlorate derived from rocket fuel manufacturing and testing activities and agricultural perchlorate derived predominantly from imported Chilean (Atacama) nitrate fertilizer, along with a likely component of indigenous natural background perchlorate from local wet and dry atmospheric deposition. Most samples within each plume reflect either a predominantly synthetic or a predominantly agricultural perchlorate source and there is apparently a minor contribution from the indigenous natural background perchlorate. The existence of isotopically distinct perchlorate plumes in this area is consistent with other lines of evidence, including groundwater levels and flow paths as well as the historical land use and areal distribution of potential perchlorate sources.     

A log‐normal spectral analysis of inorganic grain‐size distributions from a Canadian boreal lake core: Towards refining depositional process proxy data from high latitude lakes

Better methods for interpreting grain‐size spectra will enhance current understanding of past transport–depositional processes. A high‐resolution inorganic grain‐size dataset has been measured from a freeze core extracted from ‘Alberta Lake E’ a boreal fresh water lake 40 km east of the Athabasca Oil Sands in north‐eastern Alberta, Canada. The grain‐size spectra are remarkably consistent throughout the core, exhibiting a structure comprising six persistent grain‐size distributions below ca 250 μm, plus a rare medium‐sand distribution. Automated deconvolution of the grain‐size spectra produced poor results. Constraining the modes of two of the distributions produced deconvolution solutions that were statistically excellent and consistent with the structure of each spectrum. Statistical analysis of the ‘constrained’ solutions indicates that deconvolution successfully extracted independent grain‐size populations. Conversely, the multimodal spectra generate traditional measures (for example, mean grain size) that are inconsistent combinations of different individual populations and thus are poor proxies of transport–depositional processes. Alberta Lake E is situated in a boreal wetland landscape where sediment delivery is dominated by overland flow transport during spring melt. This context means that the Alberta Lake E grain‐size spectra can be interpreted to reflect: (i) a bedload component transported during short‐duration high discharge events that reflect the intensity of the melt; and (ii) a finer suspended load component representing material whose magnitude is controlled by the volume of the spring melt. Stratigraphically, bedload and suspended load populations demonstrate different short‐wavelength and long‐wavelength cyclicity, suggesting that spring melt is likely to be driven by cyclic external forcing factors. The links between the grain‐size spectra and spring melt have potential for generating proxy records that better capture the external controls over spring melt in boreal systems and the risks associated with these energetic hydrodynamics. This is exemplified by the coarsest Alberta Lake E distributions, which indicate that more intense spring‐melt dynamics occurred in pre‐historical times.     

Controls on the contemporary distribution of lake thecamoebians (testate amoebae) within the Greater Toronto Area and their potential as water quality indicators

Thecamoebians were examined from 71 surface sediment samples collected from 21 lakes and ponds in the Greater Toronto Area to (1) elucidate the controls on faunal distribution in modern lake environments; and (2) to consider the utility of thecamoebians in quantitative studies of water quality change. This area was chosen because it includes a high density of kettle and other lakes which are threatened by urban development and where water quality has deteriorated locally as a result of contaminant inputs, particularly nutrients. Fifty-eight samples yielded statistically significant thecamoebian populations. The most diverse faunas (highest Shannon Diversity Index values) were recorded in lakes beyond the limits of urban development, although the faunas of all lakes showed signs of sub-optimal conditions. The assemblages were divided into five clusters using Q-mode cluster analysis, supported by Detrended Correspondence Analysis. Canonical Correspondence Analysis (CCA) was used to examine species-environment relationships and to explain the observed clusterings. Twenty-four measured environmental variables were considered, including water property attributes (e.g., pH, conductivity, dissolved oxygen), substrate characteristics, sediment-based phosphorus (Olsen P) and 11 environmentally available metals. The thecamoebian assemblages showed a strong association with phosphorus, reflecting the eutrophic status of many of the lakes, and locally to elevated conductivity measurements, which appear to reflect road salt inputs associated with winter de-icing operations. Substrate characteristics, total organic carbon and metal contaminants (particularly Cu and Mg) also influenced the faunas of some samples. A series of partial CCAs show that of the measured variables, sedimentary phosphorus has the largest influence on assemblage distribution, explaining 6.98% (P < 0.002) of the total variance. A transfer function was developed for sedimentary phosphorus (Olsen P) using 58 samples from 15 of the studied lakes. The best performing model was based on weighted averaging with inverse deshrinking (WA Inv, r_jack² = 0.33, RMSEP = 102.65 ppm). This model was applied to a small modern thecamoebian dataset from a eutrophic lake in northern Ontario to predict phosphorus and performed satisfactorily. This preliminary study confirms that thecamoebians have considerable potential as quantitative water quality indicators in urbanising regions, particularly in areas influenced by nutrient inputs and road salts.     

Hypsographic Demography Across Scale

The typical framework for assessing human population distribution is across a flat, two-dimensional landscape. We alter this perspective by examining population distribution with respect to a third dimension, elevation. This alternative framework, termed hypsographic demography, conceptually provides a more complete visualization and understanding of population distribution. We apply hypsographic demography to North Carolina from the scale of the entire state to streams of different sizes. At the state scale, elevation and population are generally inversely correlated. The flat coastal plain contains the majority of the population at low elevations, whereas higher elevations contain smaller populations due to steep topography, which limits development. At the county scale, the historic location and expansion of cities was more closely correlated with observed patterns of hypsographic demography than elevation or topography. At the scale of the stream, the influence of topography on hypsographic demographics gains importance where topography limits the land available to develop. We use this approach to illustrate how changing the perspective for viewing population distribution can be applied to floodplain policy.     

Quantitative multi-risk analysis for natural hazards: a framework for multi-risk modelling

This paper introduces a generic framework for multi-risk modelling developed in the project ‘Regional RiskScape’ by the Research Organizations GNS Science and the National Institute of Water and Atmospheric Research Ltd. (NIWA) in New Zealand. Our goal was to develop a generic technology for modelling risks from different natural hazards and for various elements at risk. The technical framework is not dependent on the specific nature of the individual hazard nor the vulnerability and the type of the individual assets. Based on this generic framework, a software prototype has been developed, which is capable of ‘plugging in’ various natural hazards and assets without reconfiguring or adapting the generic software framework. To achieve that, we developed a set of standards for treating the fundamental components of a risk model: hazards, assets (elements at risk) and vulnerability models (or fragility functions). Thus, the developed prototype system is able to accommodate any hazard, asset or fragility model, which is provided to the system according to that standard. The software prototype was tested by modelling earthquake, volcanic ashfall, flood, wind, and tsunami risks for several urban centres and small communities in New Zealand.     

Paleoenvironmental reconstruction of the Early to Middle Miocene Central Paratethys using stable isotopes from bryozoan skeletons

Stable carbon and oxygen isotope values from single bryozoan colonies were used to reconstruct the paleoenvironments of the Early to Middle Miocene (Ottnangian to Badenian) sediments of the Central Paratethys. This approach utilizes a locally abundant allochem while avoiding matrix and multiple allochem contamination from bulk rock samples. Bryozoan colonies (and a few foraminifera and rock matrix samples) from 14 localities yielded 399 carbon and oxygen isotope values. Data from six of the localities (15 % of the total number of samples) were interpreted as having been diagenetically altered and were rejected. The remaining data indicate a primarily localized upwelling signal with lesser variation caused by global climatic and regional tectonic forcing of sea level, salinity, and temperature. Paleotemperatures were calculated to range from 12 to 21 °C. Despite potential taxonomic and diagenetic problems, bryozoan colonies are a powerful, underutilized source of paleoenvironmental carbon and oxygen isotope data.     

Book reviews

APPLIED GEOGRAPHY: Issues, Questions and Concerns (Geo Journal Library Vol. 15) edited by M. S. Kenzer. 16 × 24 cm, x and 210 pages. Kluwer: Dordrecht 1989 (ISBN 0 7923 04381).

WINE AND THE VINE: An Historical Geography of Viticulture and the Wine Trade by T. Unwin. 16 × 24 cm, xvi and 409 pages. Routledge: London 1991 (ISBN 0 415 13120 6) $A155.00 (hard); distributed by The Law Book Co.

WATERFRONT SYDNEY 1860–1920 by G. Aplin and J. Storey. 26 × 18 cm. 144 pages. Allen & Unwin: Sydney 1991 (first published 1984) (ISBN 1 86373 098 2) $A24.95 (soft).

Australian Geographer 23 (2), November 1992

INDUSTRIAL LOCATION: Principles and Policies (Second Edition) by K. Chapman and D. F. Walker. 15 × 23 cm, xiii and 322 pages. Basil Black‐well: Oxford 1991 (ISBN 0 631 16789 7) $A39.95 (soft).

INTERNATIONALISATION OF AUSTRALIA'S SERVICE INDUSTRIES by J. V. Langdale. 17 × 25 cm, iv and 373 pages. Australian Government Publishing Service, for Department of Industry, Technology and Commerce: Canberra 1991 (ISBN 0 644 13841 6).

TOURISM AND GOLD IN KAKADU: The Impact of Current and Potential Natural Resource Use on the Northern Territory Economy by B. Knapman, O. Stanley and J. Lea. 21 × 29 cm, vi and 49 pages. North Australia Research Unit, Australian National University: Darwin 1991 (ISBN 0 7315 1179 4).

ABORIGINAL AUSTRALIA AND THE ‘NEW FEDERALISM’ INITIATIVE (Discussion Paper No. 2) by G. J. Crough. 14 × 21 cm, 42 pages. North Australia Research Unit, Australian National University: Darwin 1991 (ISBN 0 7315 1325 8).

AUSTRALIAN NATIONHOOD AND OUTBACK INDIGENOUS PEOPLES (Discussion Paper No. 1) by P. Jull. 14 × 21 cm, 38 pages. North Australia Research Unit, Australian National University: Darwin 1991 (ISBN 0 7315 1309 6).

MIGRATION AND DEVELOPMENT IN THE SOUTH PACIFIC (Pacific Research Monograph No. 24) edited by J. Connell. 17 × 25 cm, xii and 199 pages. National Centre for Development Studies, Australian National University: Canberra 1990 (ISBN 0 07315 0668 5) $A25.00 (soft).

POPIULESIN BLONG HONIARA: Olketa Popiulesin Map Blong 1986 Sensis. HONIARA: 1986 Census Atlas (Statistics Office Occasional Paper No. 4 / Board of Development Studies Monograph No. 1) by A.C. Walsh. 21 × 29 cm, vii and 95 pages. Department of Statistics: Honiara and Board of Development Studies, Massey University: Palmerston North 1990 (ISSN 0114 8834) $NZ34.00 in New Zealand, $NZ38.00 elsewhere (soft).

DOI MOI: Vietnam's Renovation Policy and Performance (Political and Social Change Monograph No. 14) edited by D. K. Forbes, T. H. Hull, D. G. Marr and B. Brogan. 15 × 22 cm, xiv and 263 pages. Department of Political and Social Change, Australian National University: Canberra 1991 (ISBN 0 7315 1303 7).