MILK RIVER IN SOUTHERN ALBERTA: A CLASSIC UNDERFIT STREAM

underfit stream (un-der-fit) A misfit stream that appears to be too small to have eroded the valley in which it flows; a stream whose volume is greatly reduced or whose meanders show a pronounced shrinkage in radius. It is a common result of drainage changes effected by capture, by glaciers, or by climatic variations (Bates and Jackson 1987, 712).     

Changes in sub‐water table fluid flow at the end of the Proterozoic and its implications for gas pulsars and MVT lead–zinc deposits

A fundamental change in the nature of sub‐water table fluid flow occurred at roughly the Proterozoic–Phanerozoic boundary when organic matter began to be buried in sufficient quantities that nonaqueous fluids could occupy a significant fraction of the pore space. This allowed the formation of remarkably durable capillary seals that could trap gas in large portions (hundreds of kilometers) of a basin for hundreds of millions of years. Gas loss from these gas zones can be highly dynamic, especially during gas generation. Under the right circumstances, hundreds of cubic kilometers of gas can be rapidly discharged into adjacent permeable aquifers. In Pennsylvanian/Permian time, the Arkoma Basin may have repeatedly discharged such volumes of gas into the very permeable Cambrian sandstone and karstic carbonate aquifers of the mid‐continent of the United States. This could have displaced brines rapidly enough to form the Mississippi Valley‐type (MVT) lead–zinc deposits of this age that are associated with the Arkoma Basin, heating them only briefly as required by maturity indicators. Sea level rise accompanying the melting of Permian continental glaciers may have triggered the gas expulsion events. This radically new mechanism for the formation of MVT deposits is just one example of the nonlinear dynamics of gas accumulations that are possible since Late Proterozoic time.     

Climate change-induced migration and violent conflict

In a world of rising sea levels and melting glaciers, climate change is most likely occurring but with uncertain overall effects. I argue that we can predict the effects of climate change on migration by exploring the effects of environmental problems on migration in recent decades. People can adapt to these problems by staying in place and doing nothing, staying in place and mitigating the problems, or leaving the affected areas. The choice between these options will depend on the extent of problems and mitigation capabilities. People living in lesser developed countries may be more likely to leave affected areas, which may cause conflict in receiving areas. My findings support this theory, and suggest certain policy implications for climate change.     

The last glaciers in part of the South East Grampians

In an area of 400 sq km in the south east Grampians including Glen Esk, Glen Clova and part of Glen Muick the limits of former corrie glaciers, valley glaciers and a plateau ice‐cap with associated outlet glaciers have been mapped. The limits of the former corrie and valley glaciers are often clearly defined by end moraines, boulder‐strewn ground, the down‐valley termination of hummocky moraines and/or the limits of meltwater channel systems, while in suitable locations outwash terraces usually occur. The glaciers are considered to have formed during the Loch Lomond (pollen zone III) Readvance, when new glaciers developed in upland sources following complete ice‐sheet decay. The readvance was accompanied in granite areas by the formation of large solifluction lobes, these lobes being found only outside the mapped ice limits. The interpretations presented are not in accord with those recently given by D. E. Sugden for the western Cairngorms.     

Underground drainage at Mole Creek,Tasmania

Complex patterns of groundwater flow exist in the Mole Creek karst area, Tasmania. Many surface drainage divides are breached underground The evolution of the drainage has been dominated by (I) the deflection of streams along the strike of the limestone beds; (2) progressive changes to hydraulic gradients; and (3) a history of climate change during the Quaternary that has seen drainage diverted underground by glaciers and/or by proglacial and periglacial sedimentation     

Multiple Glaciation of the Upper Franklin Valley,Western Tasmania Wilderness World Heritage Area

Part of an extensive ice cap that developed in the Tasmanian Central Highlands during the late Cainozoic discharged southwards into the valley of the Franklin River and its upper tributaries where it merged with smaller glaciers that accumulated behind local snowfences. Glacial landforms and sediments in the now heavily forested valleys indicate that at least three and possibly as many as six glaciations took place. The earliest and most extensive glaciation occurred during the Pliocene or earliest Pleistocene. At this time ice extended at least 27km down the Franklin Valley and covered at least 326km² of the study area. This ice was confluent with glaciers in the West Coast Range to the west and in the Derwent Valley to the east Such confluence offers the possibility of better correlation of glacial events between western Tasmania and the Central Highlands. The smallest and most recent glaciation occurred during the late Last Glacial Stage when the Franklin Glacier did not exceed 12km in length. The glaciers were characterised by high rates of mass throughput and were of temperate maritime type.     

Satellite image analysis of changes in glacier cover in Canada's northern Mackenzie Mountain Range (1987–2017)

The state of a group of glaciers in the northern Mackenzie Mountains across the Yukon‐Northwest Territories border was investigated over a period of three decades, using Landsat TM and OLI imagery from 1987, 1994, 1999, 2004, 2013, and 2017 to examine changes in glacier extents. A thresholded red/shortwave infrared band ratio image was used to delineate glacier boundaries. The total area of 74 glaciers in the study area decreased from 52.78 ± 1.32 km² in 1987 to 24.89 ± 0.62 km² in 2017, a loss of 27.89 ± 1.39 km² or 52.8 ± 2.6%, with a mean rate of reduction of 1.8% · a^?1. Smaller glaciers experienced larger relative changes in area. In this study, the rates of reduction are high compared to decreases reported for other glaciers in the region in the late 20^th century. Based on linear extrapolation of the trend in values of total glacier area, it is predicted—subject to uncertainties in how glaciers diminish in size and eventually disappear—that the study area could be free of visible glacier cover within three decades.     

History and Effects of Channelisation on the Latrobe River,Victoria

Channel changes on the lower Latrobe River since the late 1800s include a 25 per cent reduction in channel length due to artificial meander cutoffs, increases in mean channel width, increased channel instability and incision of up to 1.05 m. Hydraulic changes at the Rosedale gauge include increases in bankfull flow velocity and a 67 per cent increase in channel capacity, resulting in a threefold reduction of over-bank flow duration. The extensive channelisation works have reduced the frequency of minor flooding and the period offloodplain inundation, but these and other human impacts have severely degraded the stream environment.     

Dating the Ascope Canal System: Competition for Water during the Late Intermediate Period in the Chicama Valley,North Coast of Peru

Here we present the first ¹⁴C ages for the Ascope Canal System (ACS), a large prehispanic hydraulic network in the Chicama Valley on the north coast of Peru. Composed of multiple alignments that irrigated areas north of the river, our results indicate that the ACS was constructed and operated in the Late Intermediate Period, ca. a.d. 1000–1400. This overlaps in time with the Chicama-Moche Intervalley Canal that diverted water on the south side of the Chicama River and extended to the city of Chan Chan. Conservative estimates of discharge capacity indicate that the combined flow through the canals would have exceeded stream flow in the Chicama River during half of the year. The ACS appears to have functioned for several centuries and would have been in direct competition with the Intervalley Canal. There was, apparently, insufficient water for both systems and other Chicama Valley canals during most of the year. This study underscores the complexities of understanding the operations and histories of irrigation systems in complex societies.     

Hydraulic Analysis of a Self-Cleaning Drainage Outlet at the Hellenistic City of Priene

At the distal western end of a main drainage canal running along West Gate Street in the Hellenistic city of Priene, an unusual masonry outlet structure has been found. The housed structure contains a doubly curvilinear, contracting rectangular cross-section flow passageway that allows drainage water flow through the city perimeter wall. A computer model of the complexly-shaped drainage structure has been hydraulically analysed in order to determine the function of the curvilinear passageway. Results indicate that the internal shaping of the structure hydraulically conditions the flow to create multiple circulatory mixing flows that agitate and entrain debris in the outflow stream sufficient to “self-clean” the outlet, thus preventing clogging. Further calculations of flow free surface shapes at different flow rates indicate the maximum flow capacity that can be processed by the drainage system without overspillage to provide a lower-bound estimate of the steady-state water supply to the city. The design of a self-cleaning, continuous flow urban wastewater system implies that Greek city planners maintained a high level of awareness about the hygienic conditions needed to maintain the health of the populace. The Greek attitude toward technical refinements necessary to improve the quality of urban life could therefore not be better represented than in attention to detail related to water supply and waste water drainage systems as a key to improved life standards.     

Glaciation of the Upper Forth River Catchment,Tasmania

The Upper Forth Valley was glaciated on at least four occasions during the late Cainozoic. The two most extensive glaciations were no younger than early Pleistocene in age. During the last glaciation the limited ice catchment at the head of the valley nourished only a short valley glacier with separate glaciers forming in the tributary valleys to the west During earlier glaciations the Forth catchment was invaded by ice from the Mersey Valley to the east.     

A teacher/student commentary on a field test of Manning's roughness coefficient

Abstract

This paper describes and appraises a two‐day field project designed by a member of staff to be carried out by a group of students in a series of stream sections. The main aims of the project were (1) to help students develop a better understanding of stream processes, but more importantly (2) to help students develop an awareness of how ideas evolve, (3) how to test their ideas using a sound procedural methodology and (4) how to assess the implications of their results. The paper outlines how the project developed in collaboration with six students, examines the varying contributions made by staff and students at each stage and discusses the problems that arose during its execution. The project itself involved determining the most accurate method of predicting mean flow velocity in a stream using three different methods of estimating Manning's roughness coefficient.     

Impacts of Pleistocene glaciation on large‐scale groundwater flow and salinity in the Michigan Basin

Pleistocene melting of kilometer‐thick continental ice sheets significantly impacted regional‐scale groundwater flow in the low‐lying stable interiors of the North American and Eurasian cratons. Glacial meltwaters penetrated hundreds of meters into the underlying sedimentary basins and fractured crystalline bedrock, disrupting relatively stagnant saline fluids and creating a strong disequilibrium pattern in fluid salinity. To constrain the impact of continental glaciation on variable density fluid flow, heat and solute transport in the Michigan Basin, we constructed a transient two‐dimensional finite‐element model of the northern half of the basin and imposed modern versus Pleistocene recharge conditions. The sag‐type basin contains up to approximately 5 km of Paleozoic strata (carbonates, siliciclastics, and bedded evaporites) overlain by a thick veneer (up to 300 m) of glacial deposits. Formation water salinity increases exponentially from <0.5 g l^?1 total dissolved solids (TDS) near the surface to >350 g l^?1 TDS at over 800 m depth. Model simulations show that modern groundwater flow is primarily restricted to shallow glacial drift aquifers with discharge to the Great Lakes. During the Pleistocene, however, high hydraulic heads from melting of the Laurentide Ice Sheet reversed regional flow patterns and focused recharge into Paleozoic carbonate and siliciclastic aquifers. Dilute waters (<20 g l^?1 TDS) migrated approximately 110 km laterally into the Devonian carbonate aquifers, significantly depressing the freshwater‐saline water mixing zones. These results are consistent with ¹⁴C ages and oxygen isotope values of confined groundwaters in Devonian carbonates along the basin margin, which reflect past recharge beneath the Laurentide Ice Sheet (14–50 ka). Constraining the paleohydrology of glaciated sedimentary basins, such as the Michigan Basin, is important for determining the source and residence times of groundwater resources, in addition to resolving geologic forces responsible for basinal‐scale fluid and solute migration.     

Morphological Impacts and Implications of a Trial Release on the Wingecarribee River,New South Wales

A trial, monitored release on the Wingecarribee River over 27 days had a peak discharge below the Wingecarribee Dam of 1090 ML/d, which had a flow duration of 0.95 per cent. Morphological impacts on 29 km of channel below the dam included bank erosion, concentrated neck overflow, bed degradation and channel widening at recent cutoffs, sedimentation in weir pools and overbank flow, particularly at discharges greater than 800 ML/d. Prolonged operational releases at bankfull discharge (400–800 ML/d) will have the greatest morphologic impacts and should be avoided. Pulses which dissipate stream power over a broad, well-vegetated floodplain should be incorporated in the operational release policy, provided such pulses are phased to facilitate channel and vegetation recovery.     

Implications of climate change for glacier tourism

For more than 100 years, the Fox and Franz Josef Glaciers in Westland Tai Poutini National Park have attracted thousands of tourists annually and have emerged as iconic destinations in New Zealand. However, in recent years, the recession of both glaciers has been increasingly rapid and the impacts on, and implications for, visitor experiences in these settings remain relatively unexplored. A mixed-method approach was adopted to investigate visitor experiences and stakeholder perspectives through an assessment of climate-related changes on tourism at the glaciers in Westland Tai Poutini National Park. The bio-physical conditions at both the Franz Josef and Fox Glaciers were reviewed in order to assess the magnitude and rate of retreat. Perceptions of climate change risk and awareness of impacts in the National Park were assessed through stakeholder interviews (n = 13) and a visitor survey (n = 500) was used to better understand how impacts at these sites have affected and may continue to affect visitor experiences. Research results were reported to local communities via a series of public talks. Results revealed the fundamental importance of viewing the glaciers as a significant travel motive of visitors, suggesting that there is a ‘last chance’ dimension to their experience. Furthermore, the results demonstrate a high adaptive capacity of local tourism operators under rapidly changing environmental conditions. The implications of altered visitor experiences for tourism operators and protected area managers are discussed in light of these findings.     

Wavelength‐dispersive X‐ray fluorescence analysis of ancient glasses*

The application of X‐ray fluorescence to the study of the composition of ancient glasses has been limited by the large amount of material required for samples. In this paper the setting of a reduced sampling XRF method for the analysis of ancient glasses is described. The method involves the preparation of glass beads by melting the sample with lithium tetraborate flux. By means of reference and synthetic samples, the method allows regression curves to be set, covering broad ranges from ppm to high concentrations. By means of a single program, up to 31 elements of interest in the study of ancient glass are analysed. The reproducibility, sensitivity and reliability of the method are discussed. The results demonstrate that 0.2 g of glass is sufficient to obtain accurate and sensitive analyses for most of the elements of interest.     

The Aral Sea Problem and its Solution

A hydrogeologist suggests that nine-tenths of the present stream flow into the Aral Sea can be diverted for other purposes without causing the sea to dry up. The diversion would cause the sea level to drop by 12 meters, where it would stabilize because of a greater intake of subsurface runoff resulting from an increased artesian pressure differential, and because the draining of flooded shore areas and the drying up of reed growths will make more water available through savings in evaporation and transpiration.     

论明前期斡朵里女真与明、朝鲜的关系--兼论女真对朝鲜向图们江流域拓展疆域的抵制与斗争

本对斡朵里女真与明、朝鲜的关系进行了考述。认为斡朵里女真自洪武初年已迁徙朝鲜吾音会,至正统五年(144)西迁苏子河畔,中间除西迁辽东凤州十余年外,一直居住图们江流域。斡朵里女真居住图们江流域对李朝政府向图们江流域拓展疆域进行了有效地抵制和斗争,致使李朝以图们江为界的欲望始终难以实现。     

An Element of Thought: Phosphorus and Mental Philosophy in the Nineteenth Century

Georges Cabanis (17571808), through his writings on the relation of the physical and moral, or psychological, aspects of man, left a legacy that made the study of mental activity a part of physiology. His views on the importance of phosphorus to the function of the brain thrust that element into a prominent stream of research that involved many investigators in several countries. Although that particular stream eventually dried up, its influence remained: by the beginning of the twentieth century basic medical science had become well set on studies of the mind-body relationship.     

A Preliminary Study on the Loss of Iron and Arsenic in the Re‐Melting of Iron‐Bearing Arsenical Copper

Re‐melting experiments were conducted with specimens made of high‐arsenic copper alloys containing lead, iron and sulphur. The melting treatment at 1000°C in ambient conditions for 5 min was found to cause an almost complete removal of iron and sulphur along with a notable reduction of arsenic levels. Evidence was found that the preferential oxidation of iron and arsenic was responsible for this change in composition. The treatment also brought about perfect dissolution of speiss particles scattered throughout the original specimen, suggesting the possibility of the addition of speiss to molten copper for the production of arsenical copper.