The karst of Sagada Mountain Province,Luzon, Philippines

Speleological investigations during a three month period in late 1982 and early 1983 in the karst of Sagada, Mountain Province, Luzon, Philippines further clarified the initial 1980 study by Deharveng and Orousset. Over 13 km of cave passages were mapped and two main watersheds, Ambasing Spring and Balangagan Spring, were recognized.

The karst of Sagada lies between 1100 and 1600 m elevation in the Oligocene limestones of the Tineg formation. The karst is well developed, both on the surface and in the subsurface. The caves fall into five main types:

1. Potholes (Kitungan Kampus Pit, entrance to Tataya En).

2. Fossil Caves (Lomyang Cave, upper part of many caves).

3. Swallets (Latang Cave, many small swallets, especially during the wet season).

4. Underground rivers (Agoyo-Ige System. Lomyang-Latipan System, Agew Na Nayawakan System, Tataya En System, part of Balangagan Cave).

5. Springs (Ambasing and Balangagan Springs).

The caves are characterized by very wide passages, massive secondary calcite deposits, voluminous collapses, abundant volcanic debris and floods up to 600 times the low flow discharge. Study is not complete, and much work needs to be done, especially to differentiate completely the watersheds of the two main springs.     

Danske provinsbyers indre differentiering og differentieringen mellem danske provinsbyer

Pedersen, P. O. & Rasmussen, P., 1973: Danske provinsbyers indre differentiering og differentieringen mellem danske provinsbyer. Geografisk Tidsskrift, 72, 49–56. København, September 30., 1973.

This paper analyses the inner differentiation in the three largest provincial towns in Denmark by means of a factor analysis of 25 variables characterizing the population and the housing in 40 zones, 14 in Århus (187,000 inh.), 14 in Odense (133,000 inh.), and 12 in Ålborg (123,000 inh.). The paper especially focuses on the differences in inner differentiation between the three towns.     

Quaternary glacial events in the Pyrenees from U-series dating of speleothems in the Niaux-Lombrives-Sabart caves,Ariège,France

Located at approximately 150 m above the present base level, the caves of Niaux, Lombrives and Sabart are an old drainage system, which worked between the Vicdessos and Ariège Valleys. In these caves, three successive sedimentary units were studied in detail. Each unit consists of two parts: the lower deposit is detrital, of fluvial origin, and testifies to a hydrological working of the conduit system; the upper deposit of each unit is mostly speleothems, corresponding to a draining of the conduits as the palcokarst evolved above base level. This is similar to the present environment of the caves.

Only the speleothems from the upper part of each unit were dated by the ²³⁰Th/²³⁴ U method. The dates, from 27 samples, are in good agreement with Europe and North America data. The data from the middle (250 to 200 ka BP) and upper (90 to 20 ka BP) fluvial sediments correspond to major glacial events, which re-activated the karst system.

Two further events resulted in a lack of carbonated sedimentation, the first between 350 and 290 ka BP, the second between 175 and 130 ka BP. Comparing the data from other places, these two events can be related to glacial periods of minor importance in the study area, because of the lack of erosion and of detrital sediments.

The oldest detrital sediments are covered by speleothems older than 350 ka BP and, partly, older than 720 ka BP (from paleomagnctic data to be confirmed); from sedimentary data, they may not be related to a glacial event. They are perhaps contemporary with the area's initial cave formation.     

Evidence of subglacial karstification in Glomdal,Svartisen, Norway

The central Glomdal caves, Storbekkgrotta and Kalkrastgrotta, are found within a 30 m (approximately) thick band of white marble. The karst system is allogenic and the cave morphology and surface topography provide evidence of several phases of development:

1. Phreatic conduit development.

2. Drainage and vadose incision.

3. Partial or complete infill with clastic (glaciogenic) sediments.

4. Glacial truncation of the conduits.

5. Reversed, phreatic flow in the up-hill direction, producing paragenetic halftubes and rock pendants.

6. Partial outwash of the previous infilling sediment.

7. Holocene vadose invasion.

Since the paragenetic features are superimposed onto vadose features, the reversed flow must have occurred after base-level (i.e. bedrock) lowering. Together with the topographical situation of the karst, phase 5 (paragenesis under reversed flow) may be explained by subglacial water flow. This implies a temperate glacier sole at a time when the icefield could over-ride the local valley topography and provide an up-hill directed englacial hydraulic gradient.

The results suggest that sub-glacial water flow may utilize pre-existing karst conduits (which are extremely stable Nye-channels in the glaciohydrologic context) and enlarge them somewhat. It is still not proven that entire cave passages with radii of 1 to 2 m may form under such sub-glacial conditions, as suggested by Horn in 1947. The chemistry and conduit hydrology of deep sub-glacial waters are crucial parameters in this regard.     

Subglacial Observations at Østerdalsisen,Svartisen

Summary

Studies at Østerdalsisen have revealed that there is little active erosion within subglacial caves under present conditions. Abrasion seems to be the major process occurring at the bed, but only a rather small amount of material is transported by the glacier. Rock cliffs beneath the glacier seem to be protected by a coating of ice for much of the year, and the transport of material towards the centre of the valley by snow meltwater in the spring is the principal geomorphological activity in the caves.     

Faunal records in Norwegian karst caves

Until recently, the amount of published information available about the fauna in Norwegian karst caves has been very limited. The Karst Research Project in Norway, established in 1977, has considerably expanded our knowledge in this field.

As ecosystems, Norwegian karst caves can be divided into two types: 1) open systems – connecting directly to the surface, with rivers or brooks entering through discrete openings. Most animals are surface or surface-related forms which may survive but rarely can reproduce underground. True cavernicoles are not often found; 2) infiltration systems – are fed by seepage water from overlying material, and show a more complex and interesting cave ecosystem, including troglophilic and troglobitic forms (which, with few exceptions, are invertebrates). Vertebrate data from caves in Norway consist of fossils and unfossilized bone remains, usually of mammals. These represent accidentals from stream and pit-fall traps, as well as remains of predator dens.

Two on-going research projects in Norway arc: 1) the Ecosystem Study in Bevergrotta – sampling of the environment and contents has been continued for several years, and has shown this to be one of the most significant cave ecosystems in Norway; 2) Mammalian Remnants in Caves – sampling is still in the preliminary stage, and has collected only exposed remains. The data at present indicate bones of 5700 years old or younger. Clearly deeper sampling over a broad geographic area needs to be done.     

Södra Finlands blocksänkor

Söderman, G.: Södra Finlands blocksänkor. Geografisk Tidsskrift, 82, 77–81, November 1. 1982.

Map analysis and field inventory show that there are about 20000 boulder depressions in Finland south of 64°N. The features are most common in blocky till areas close to fracture zones in the bedrock. The depressions range in altitude from above the highest shore-line down to 25–30 m above present sea-level. They are youngest in the NW part. Some depressions show surface patterns.

SAMMANDRAG

Blocksänkor är frostmarksformer med en huvudsakligen vertikal sortering som ett resultat av differentiell uppfrysning av blockrikt utgångsmaterial. De framställer inga klimatiska kriteria om utbildningstid och -förhållanden. Däremot här de till områden med sasängbetonad frostaktivitet, och om ej inskränkta till nedisade omräden, trots typiska fär dessa. Blocksänkorna är den mest utbredda och största frostmarksform inom den fennoskandiska skogsregionen i dag.     

Water chemistry of some karst environments in Norway

In August 1983, 18 samples were collected in Norwegian karst environments: seepage waters, surface flow upstream sinkholes or caves, allogenic and authigenie karst springs. Hydrochemical data (ion contents and computed variables for CO-CaCO system) are described by means of a factor analysis, the principal components analysis. Four factors, responsible for about 90 % of the total variance, are extracted and interpreted. Five clusters of samples are then identified:

– Authigenic karst waters (seepage and only carbonate aquifer);

– Waters of very short residence time (surface or karst flow);

– CO-rich waters (seepage and possibly organic-rich surface waters), CO2 part is discussed in more detail;

– CO-poor waters (surface waters above tree-line);

– a central group, combining 2 or more of these characters.     

Exploring the uncertainty of activity zone detection using digital footprints with multi-scaled DBSCAN

ABSTRACT

The density-based spatial clustering of applications with noise (DBSCAN) method is often used to identify individual activity clusters (i.e., zones) using digital footprints captured from social networks. However, DBSCAN is sensitive to the two parameters, eps and minpts. This paper introduces an improved density-based clustering algorithm, Multi-Scaled DBSCAN (M-DBSCAN), to mitigate the detection uncertainty of clusters produced by DBSCAN at different scales of density and cluster size. M-DBSCAN iteratively calibrates suitable local eps and minpts values instead of using one global parameter setting as DBSCAN for detecting clusters of varying densities, and proves to be effective for detecting potential activity zones. Besides, M-DBSCAN can significantly reduce the noise ratio by identifying all points capturing the activities performed in each zone. Using the historic geo-tagged tweets of users in Washington, D.C. and in Madison, Wisconsin, the results reveal that: 1) M-DBSCAN can capture dispersed clusters with low density of points, and therefore detecting more activity zones for each user; 2) A value of 40 m or higher should be used for eps to reduce the possibility of collapsing distinctive activity zones; and 3) A value between 200 and 300 m is recommended for eps while using DBSCAN for detecting activity zones.     

安徽齐云山丹霞地貌成因

According to the study of some local scholars (Peng Hua et al., 2000), over 400 sites of Danxia landform have been already discovered in China. Chen Guoda (1935), Zeng Zhaoxuan et al. (1978), Huang Jin et al. (1992; 1994; 1996) and Peng Hua et al. (1998; …     

Meteorological Observations in 1995 at the Arctic Station,Qeqertarsuaq (Godhavn), Central West Greenland/Concentrational Agriculture: Types,Functions, and Derivation/Den Danske Nationalkomité for Geografi

In October 1990 an automatic meteorological station was established at the Arctic Station (69°15'N, 53°31'W), Qeqertarsuaq (Godhavn), Central West Greenland, The station register parameters each 20 min, and the parameters have been described in an earlier paper in this journal by Nielsen et al. (1995). The present paper summarises main points of the climate during 1995.

Concentrational agriculture, defined as types of agriculture based on local concentration of plant nutrients, encompasses two main types: shifting cultivation and infield-outfield systems. They may ecologically be characterised by their mode of concentration: either by a vertical or a horisontal transfer (‘pumping’) of nutrients, respectively. The use of the general term ‘concentrational agriculture’ for the two forms is advocated by demonstrating that functional substitution of one by the other is possible, and by showing that the one type theoretically can be derived from the other. Historically, infield-outfield systems are supposed to be developed from some form of shifting cultivation.

Kort beretning om virksomheden i 1995

Justering af medlemskredsen. I forbindelse med valg af repræsentanter fandt en justering af repræsentationsområder sled (Århus Universilet har ikke længere fagområdet ‘kulturgeografi’). Videnskabernes Selskab har i samme forbindelse bifaldet, at fire observatører, repræsenterende undervisningstrinene i geografi deltager i møderne.     

Impacts of Wildlife on Agriculture: A Spatial-Based Analysis and Economic Assessment for Reducing Damage

Over the last few years, the impacts of wildlife on agriculture have constantly been growing, in particular in areas close to woodland and in hunting ban zones (“refuge effect”). Public administrations have difficulty in meeting the growing requests for crop damage compensation. The development of appropriate measures to control this trend—starting from the understanding of the dynamics concerned—is crucial. The aim of this study was, therefore, to analyze damage at regional scale and define common local actions. In particular, the study involved different steps that define a spatial-based classification of risk levels, integrating statistical methods (principal component analysis and receiver operating characteristic) with multi-criteria evaluation (MCE) in a geographic information system (GIS). It turns out that, in the study area, the very high-risk zones affect 8.83% of used agricultural areas; about 97% of them concentrated in the first 400 m from the most suitable habitats. A selected cluster of 11 test areas within these zones allowed us to assess the cost-effectiveness of integrated prevention and control actions (IPCA) with respect to the compensation of the damage. The analysis shows cost of IPCA to be nearly twice the actual cost incurred by the public administration to compensate partially the damage. The comparison with the estimated damage shows the overall economic convenience of the proposed investment with significant differences depending on the areas. Thus, we suggest reaching an “agro-ecological” balance starting from actions on specific areas; if they produce the desired effects, they could be progressively extended to other areas with gradual investments (adaptive management).

     

Suspended Sediment Yield from the Ansager Å river basin,Denmark

Geografisk Tidsskrift, Danish Journal of Geography 98: 38–45.

Water samples have been collected since 1969, at the Lavborg Bridge gauging station, on the river Ansager Å in South-West Jutland. Different regression equations of concentration versus discharge have been tested. The regression equations are used together with daily discharges to compute the daily suspended loads. Comparisons between measured and computedloads for different periods when water samples were taken twice a day suggest that the 25 computed annual load values have an uncertainty of less than ± 10%. The variation in annual loads shown is therefore significant and probably caused by increased rainfall in the eigthies. The average total suspended sediment yield for the 25 year period was 7 t/km²/year, of which the organic load contributed 3.2 t/km²/year.     

Jordbruket På Sunnmøre Under Industrireisingen

Et iøynefallende trekk ved den industrien som er reist på. Sunnmøre i løpet av de siste 20—30 år, er at den har fått det meste av sin arbeidskraft fra jordbruket, og at en stor del av bedriftene, særlig småbedriftene, er satt i gang av bønder og bondesønner. Den nye industrien er vokst fram utc i hygiene. Landsungdommen har derfor i liten grad flyttet til Ålesund eller andre byer; utflyttingen fra gardene har vesentlig skjedd til bygdesentrene. En stor del av jordbruksbefolkningen har ogsa deltatt i industrireisingen uten å flytte fra gardene, idet mange småbrukere og bondesønner kombinerer fabrikkarbeid og jordbruk, mens andre driver selvstendig småindustri heime på gardene.

For jordbruket har denne industrireisingen skapt store forandringer:

1) I mange bygder er det blitt vanlig a drive industriarbeid i kombinasjon med jordbruk.

2) De nye industristedene betyr nye lokale markeder for jordbruket, men de betyr ogsa at jordbruket mister folk.

3) Jordbruket har fatt tekniske impulser fra industrien.     

山区气候的立体性与农林牧的分层模式*

对华北山区年平均温度和年降水推算的基础上,计算山区自然植被净第一性生产力的垂直分布,结合山区开发对象或作物的生物学指标,建立单因子和综合因子分层开发模式。华北山区分层种植模式一般分3～4层:1～2层(下中层)为农粮层,3～4层(中上层)为经济林和用材林层。山区综合开发利用方向是巩固下层,保护上层,重点开发利用中层的立体化模式。     

Mineral magnetic signatures in a long core from Lake Qarun, Middle Egypt

The analysis and interpretation of changes in mineral magnetic signatures from a long (ca. 8.2 m) sedimentary sequence recovered from Lake Qarun, Middle Egypt in 2003 spanning a timescale of approximately the last 2,000 years is reported. A suite of mass specific susceptibility and magnetic remanence measurements were made at irregular intervals downcore on 39 samples. These samples were selected on the basis of trends and abrupt changes in whole-core magnetic susceptibility measured using a Bartington^® MS2E sensor and were analysed for low and high temperature loss on ignition and their particle size distribution. Trends in all mineral magnetic concentration parameters are remarkably similar and were initially used to divide the core into three magnetically distinct zones. The upper and lower sections of the core (0–119 cm and 445–822 cm depth) are characterised by low values for all magnetic concentration parameters. Between 153 and 380 cm depth, concentration parameters are considerably higher, although somewhat variable. The S ratio and percentage loss of remanence after 24 h (IRM_loss) follow a different trend and are inversely related to each other. A low S ratio (<0.7) is associated with a loss of remanence of >4%. On the basis of these parameters, the core can be divided into four zones, and differences in magnetic mineralogy between these four zones were confirmed by measurement of IRM acquisition curves. The major difference between concentration parameters and ratios or percentage loss of IRM lies in the identification of an additional zone below 619 cm depth where the S ratio is high and IRM_loss is low. There is little evidence to suggest that the magnetic signatures are controlled by particle size or by trends in organic matter and/or carbonate content. The signatures appear to be predominantly detrital and show little evidence of post-depositional alteration through dissolution or authigenic addition of bacterial magnetite or greigite. Analysis of Saharan dust deposition rates in Northern Egypt suggests that atmospheric fallout is likely to make only a very minor contribution (<1%) to sedimentation rates in Lake Qarun. The downcore trends therefore appear to reflect major changes in fluvial sediment sources over the ca. 2,000 year time period spanned by this ～8 m core. Preliminary mineral magnetic characterisations of potential local sources suggest that these cannot account for the range of signatures recorded in the Qarun sediments and it is hypothesised that these sediments are derived from Nile river floods.     

Multi-scale Numerical Simulation and 3D Modeling for Deep Mineral Exploration in the Jiaojia Gold District,China

In this study, deposit- and district-scale three-dimensional (3D) fault-and-intrusion structure models were constructed, based on which a numerical simulation was implemented in the Jiaojia gold district, China. The numerical simulation of the models shows the basic metallogenic path and trap of the gold deposits using mineral system theory. The objective of this study was to delineate the uncertainty of the geometry or buffer zones of the ore-forming and ore-controlling fault-and-intrusion domains in 3D environment representing the exploration criteria extraction and the gold potential targeting in the study area. The fast Lagrangian analysis of continua in three dimensions was used as the platform to define the stress deformation fracture ore storage and the hydrothermal seepage channel zone based on the gold deposit features and metallogenic model in the study area. The validity of the numerical simulation was verified by comparing it with robust 3D geological models of the large Xincheng gold deposit. The potential targeting zones are analyzed for uncertainty and then evaluated by Boolean operation in a 3D geological model using the computer-aided design platform. The research results are summarized as follows. (1) In the pre-mineralization period, the Jiaodong fault’s left lateral movement created the Jiaojia network faults and formed a fracture zone with NW- to NNW-trending dips of 20° to 40°. (2) During the mineralization period, hydrothermal flow was associated with the intrusion geometry and features. However, it was constrained by the Jiaojia fault, which blocked the vadose flow into the upper wall rock and made the hydrothermal route close to the fault in the footwall fracture zones. (3) Three gold potential targets were identified by the numerical simulation results in the study area: the NW-trending Sizhuang gold deposit, the NW-trending zone of Jiaojia gold deposit, and the NE-trending zone of the Xincheng gold deposit. (4) The numerical simulation results show the fault-and-intrusion metallogenic domain and the hydrothermal alteration zones, which reflect the main ore-controlling and ore-forming factors of mineralization. The information obtained through the numerical simulation discussed here can be used to define exploration criteria in the study area.

     

Technical Note The b-function and variable stream buffer mapping: a note on ‘A GIS method for riparian water quality buffer generation’

Abstract

Mapping variable stream buffers in a vector environment in which buffer width values are delineated often yields inaccurate results. Possible vector solutions are either ineffective or inefficient, An alternate raster approach is presented here in which a buffer effectiveness-achievement function (b-function) is introduced to map desirable buffer zones at an individual cell level based upon areal differentiations in physical and ecological conditions. The implementation of b-function is made feasible by a GIS procedure devised in this article. This tested method can be extended to a variety of variable buffer studies, such as visual buffers, noise buffers, greenways, and urban natural buffers.

‘A robe can never be made of the fur from one fox's axillae’ (A Chinese idiom).     

浙江瑶琳洞风化碳酸钙景观复生试验

目前,世界上80%以上的风景旅游洞穴,开放后,大量游客涌入和高能景观灯的应用,洞穴环境及能量埸和化学埸发生了巨大变化,洞穴碳酸钙景观遭受严重破坏,其景观的美学价值大大降低。文中论述了在已遭风化破坏的碳酸钙景观上滴喷高Ca⁺²碱液,吸收洞穴空气CO₂,形成CaCO₃沉积层的试验。试验结果表明,Ca⁺²碱液滴喷技术可以恢复风化碳酸钙景观的美学度,同时又降低洞穴空气中的浓度,改善洞穴环境。     

Danxia landform genesis of the Qiyun Mountain, Anhui Province

The Danxia landform of Qiyun Mountain is mainly developed on the red granule conglomerates named Xiaoyan Group (K2x1) of middle Cretaceous series, which is controlled mainly by three faulted zones, namely, Jingdezhen-Qimen faulted zone, Jiangwan-Jiekou compressional faulted zone and Kaihua-Chun’an folding faulted zone. During the Cretaceous period, this area firstly experienced massif subsidence to become a continental faulted basin, then having thick Cretaceous red sediments accumulated on it. In the supervened neotectonism, this area experienced an uplifting process, which made the thick Cretaceous sediments into a mountain with an altitude of 500-600 m. After undergoing the processes of vertical joint development, weathering, denudation and transportation, as well as evidently differential weathering and denudation influenced by lithology and structure between sandstone and conglomerate, the grand Danxia landscape consisting of peak forests, steep cliffs, caves, mesas, castellated peaks, natural bridges and so on formed. The three nick points located respectively at 585 m, 400 m and 150 m generally reflect the three dominated uplifting processes during the neotectonism.