bluuebunny/crossref_metadata_2025 huggingface dataset:
Algal growth on building sandstones: effects of chemical stone cleaning methods
Authors: Young M. E. , Urquhart D. C. M.
Published: November 2007

Biological growths including algae, lichens, bacteria, fungi and mosses are common on building sandstones wherever suitable conditions occur. Some growths, such as lichens, may be considered desirable since they can give a mature appearance to a facade, but others are often considered undesirable as they can be disfiguring and may lead to, or exacerbate, stone decay. The disfiguring of buildings and monuments by biological growths, particularly on recently cleaned buildings, is therefore a cause of some concern. Following stone cleaning, re-soiling from inorganic sources may take many years, however, re-soiling in the form of green algal growths may occur within only a few months. This paper reviews the factors which influence algal growth on building sandstone and summarizes the results of research into the effects of chemical stone cleaning with respect to algal re-growth. Results indicate that residues of some phosphate-rich stone cleaning chemicals can act as nutrients accelerating algal growth on vulnerable building sandstones.
Field and laboratory approaches to limestone weathering
Authors: Trudgill S. T. , Viles H. A.
Published: November 2007

Comparison of field- and laboratory-derived rates of chemical weathering is generally regarded as unsatisfactory. However, laboratory dissolution rates for calcite derived under realistic conditions which simulate the field situation compare well with field rates of measured limestone erosion, provided appropriate adjustments are made for periods of wetting. For physical and biological weathering there are far fewer field and laboratory studies available, and the range of different processes and process interactions makes comparisons difficult. However, period of wetting seems also to be a vital factor in more realistic comparisons between laboratory and field results. Experiments and field observations that look at the combined action of chemical physical and biological weathering are increasingly required.
Coastal weathering of greenschist in dated structures, South Devon, UK
Authors: Mottershead D. N.
Published: November 2007

Dated historic structures provide a chronological framework for the evaluation of coastal greenschist weathering over periods of up to 450 years. A weathering rate of 0.6 mm a
-1
, derived by direct methods over a short period, is shown to be valid over a span of centuries. Local variations in aspect, elevation and exposure of the structures influence weathering processes and rates. This paper is a summary of work published in full elsewhere.
Experimental production of weathering nanomorphologies on carbonate stone
Authors: Viles H. A. , Moses C. A.
Published: November 2007

Nanomorphological features (
c
. > 1 mm) produced by weathering processes can be observed with SEM and allied techniques. An experimental study using acidic water sprayed onto marble and calcite substrates reveals that weathering nanomorphologies can be produced and classified, and their occurrence quantified. Comparison with field samples shows that the experimentally produced nanomorphologies are smaller than, but morphologically similar to, naturally occurring features. Further experiments are needed to investigate and quantify nanomorphologies developed by a range of other weathering processes, and also to investigate their role in the development of larger-scale weathering features.
Influence of climatically induced cycles in physical weathering
Authors: Halsey D. P. , Mitchell D. J. , Dews S. J.
Published: November 2007

Climatically induced cycles of stone temperature and moisture content may result in physical rock weathering through various mechanisms. These mechanisms cause rock to oscillate between periods of expansion and contraction, resulting in compressive and tensile stresses. Cycles of compression and tension may cause fatigue of the stone and therefore the frequency of these cycles may be of critical importance. The temperature and moisture content of stones with four different aspects were monitored over one year and the frequency of heating-cooling, wetting-drying and freeze-thaw cycles calculated. Heating-cooling cycles were found to occur on all aspects, but the highest frequency of cycles occurred on south and west aspects during summer months. Heating and cooling of stone creates a thermal gradient within the stone, which is critical in causing insolation weathering. Differences in the rate of thermal expansion between minerals or superficially degraded parts of stone may also contribute to breakdown. Moisture availability may alter the mechanisms by which heating—cooling causes weathering. Cycles of wetting—drying are less frequent than heating—cooling cycles, but may cause weathering by five mechanisms, depending upon the hygrometric gradients. Freeze-thaw cycles show a much lower frequency than heating—cooling and wetting—drying cycles, but are active on all aspects.
Cavernous weathering in sandstone: lessons to be learned from natural exposure
Authors: Turkington A. V.
Published: November 2007

The most common small-scale weathering features on sandstone landscapes are caverns, widely known as ‘tafoni’. Caverning is by no means confined to one climatic regime; it is, however, especially well-developed in salt-rich environments, such as arid or coastal areas. Caverns are convergent forms created by a variety of different weathering mechanisms; salt may play a role in directly producing mechanical breakdown, or indirectly promoting chemical decay.

This study investigates the occurrence of tafoni on the Aztec sandstone in The Valley of Fire, Nevada and the Navajo sandstone in Zion National Park, Utah, USA. These Jurassic sandstones are similar: porous, fine-grained, quartzitic. The weathering features hich characterize them provide a marked contrast. Caverns are frequently developed in the Aztec sandstone; the Navajo sandstone is sparsely caverned, displaying sheer cliffs with arched hollows due to block collapse. The role of microclimatic variations in accelerated weathering in caverns is postulated, on the basis of field observations. Scanning electron microscope analysis suggests that an important control on tafoni occurrence is the lithology and structure of the rock.
Applied geological maps for planning and development: a review of examples from England and Wales, 1983 to 1996
Authors: Smith A. , Ellison R. A.
Published: November 2007

The former Department of the Environment has commissioned 35 applied geological mapping studies dealing with land-use planning in a range of geological and planning environments. These were carried out in England and Wales between 1983 and 1996. Using geological maps as a base these studies have developed two types of applied geological maps: thematic maps dealing with particular topics and summary maps bringing together many of the earth science factors relevant to planners and developers. The recommendations made by Geomorphological Services Limited (GSL) in 1985 in a previous review of these studies are summarized. The output, type and range of information, and its potential users are compared. Each study is assessed, with respect to the GSL recommendations, in terms of its content and usefulness, based in part on how it has been received by users. The main types of summary and thematic maps are described and guidance given on their content and presentation. The importance of maps in providing the key interface between earth scientists and planners is discussed, in particular the significance of map scale, use of colour and accuracy of the geological lines. Good practise is illustrated by reference to examples.
Long-term changes in the quality of polluted minewater discharges from abandoned underground coal workings in Scotland
Authors: Wood S. C. , Younger P. L. , Robins N. S.
Published: November 2007

Long-term trends of changes in the quality of water discharging from abandoned coal mines have been studied for 32 long-established discharges in the Midland Valley of Scotland. Six discharges have been studied in greater detail, providing insights into discharge quality evolution over more than a century. It has been found that minewater pollution is most severe in the first few decades after a discharge begins (the ‘first flush’), and that even the largest systems settle down to a lower level of pollution (particularly in terms of iron concentration) within 40 years. Long-term iron concentrations of less than 30 mg/1 are typical, and many are less than 10 mg/1. Low pH values (which might justify the over-used term ‘acid mine drainage’) do not generally persist, due to the rapid buffering of localized acidic waters by carbonates (both natural carbonates, and those introduced as rock powder for fire precautions during mining). This is corroborated by alkalinity concentrations, which tend to be highest in the early years of a discharge. While the pyrite content of the worked sequence strongly influences initial water quality (in terms of pH, iron and sulphate) during the ‘first flush’, there appears to be no correlation between long-term iron concentrations of discharges and pyrite content of local strata. Rather, higher levels are found in any sequence where there is scope for fluctuations of the water table in worked ground near to the discharge. A scientific approach to minewater remediation should allow for active treatment of discharges for the first decade or two, followed by long-term passive treatment after asymptotic pollutant concentrations are attained.
The use of shallow seismic techniques to characterize sub-surface Quaternary deposits: the example of Porth Neigwl (Hells Mouth Bay), Gwynedd, N. Wales
Authors: Brabham P. J. , McDonald R. J. , McCarroll D.
Published: November 2007

Porth Neigwl is a 6 km wide, drift-filled embayment, located on the Llyn Peninsula of northwest Wales, UK. The embayment is surrounded by hills formed of Lower Palaeozoic Rocks. Infilling the embayment is a 17 km
2
area of thick Quaternary deposits which are well exposed in the sea-cliff. These deposits have been studied intensely over the past century. However, previous workers have made little reference to the total extent or architecture of the Quaternary deposits that lie below present sea level and nothing is known about the rockhead geometry. A programme of high-resolution shallow seismic surveys are described, including 3 km of refraction and 1 km of shallow reflection profiling. Refraction results show that the Quaternary drift cover is variable in composition and thickness with a maximum thickness of 80 ± 8 m. However, results indicate that rockhead within the embayment lies consistently at an elevation of around - 32 m OD. The spatial distribution of refractor velocities is discussed. High-resolution shallow reflection surveys identify three major Quaternary sequences below present sea-level that are consistent across the area. This study demonstrates that combined seismic refraction and reflection studies are very useful in the rapid analysis of Quaternary stratigraphy and spatial depth to rockhead variations in areas of thick drift.
Geophysical investigation of proposed sites for artificial recharge in Northern Oman
Authors: Young M. E. , Al-Touqy Nasser , Khatim El , Adam Osman Abdullah
Published: November 2007

Sites in the interior of the Sultanate of Oman have been considered for the construction of recharge dams for temporarily impounding flood flows from the Northern Oman Mountains. Impounded water would be discharged under control to infiltrate into downstream aquifers. Four geophysical methods were applied to characterization of the spreading ground downstream of these sites and to guide drilling of test bores.

The main aquifers occur in permeable zones at the base of the alluvium and in the upper, weathered, bedrock. The alluvium is variably cemented and clay rich, and behaves as a confining layer between the shallow, unconsolidated surface infiltration zone and the aquifer.

The thickness of the upper unconsolidated layer of boulders and gravels was most accurately mapped with seismic refraction or vertical electrical sounding (VES). These methods were slow to apply in the arid, bouldery ground conditions and surveying was in places constrained by the wadi walls. Gravity survey, with control provided by VES, was a rapid method of profiling the total thickness of alluvium and weathered zone overlying the denser and more resistive unweathered ophiolite bedrock. VES was usefully supplemented by simultaneously measured induced polarization (IP) soundings which respond to the distribution of clay minerals.

Transient electromagnetic sounding (TEM) proved to be the most rapid method of survey as no ground contact was required. Alluvial thickness was interpreted by resistivity-depth modelling of TEM data and was most reliable over low-resistivity argillaceous mudstone or shale bedrock.
Ground penetrating radar survey to detect scour holes beneath the A525 highway at Nant-y-Garth Pass, Wales: a case history
Authors: Nichol D. , Reynolds J. M.
Published: November 2007

At Nant-y-Garth Pass, the A525 Wrexham to Ruthin Road is susceptible to undermining due to the scouring action of an adjacent fast-flowing stream. Concealed scour cavities were suspected following manual probing but the full threat posed to the integrity of the carriageway and to the safety of road users remained uncertain. Ground penetrating radar was used along a 350 m stretch of the highway to investigate the number and extent of scour holes beneath the carriageway. The survey identified extensive subsurface voiding with distinct anomalies associated with shallow cavities measuring up to 9 m long by 0.2 m high and extending as far as the centre of the road. More subdued radar features were interpreted as scoured pockets where fine-grained debris had been washed out and the remaining material had been disturbed and loosened. The results provided a basis for prioritizing countermeasures designed to repair the highway foundations and ensure the public safety.
Some geotechnical properties of the Claygate ‘Beds’ and Bagshot ‘Beds’ of south Essex
Authors: Northmore K. J. , Bell F. G. , Culshaw M. G.
Published: November 2007

The Claygate Beds and Bagshot Beds are the uppermost formations of Eocene age in south Essex, the former resting on the London Clay. The Claygate Beds consist primarily of silts and clays with subordinate sands, whilst sands are more common in the Bagshot Beds. The paper describes the geotechnical properties of these two sedimentary units. The results form part of a larger study of the engineering geology of south Essex.

The sands, particularly in the Bagshot Beds, are fine grained. All the sands are uniformly sorted and negatively skewed. Quartz is the principal minerals in these beds and in the fine material, mica, montmorillonite, kaolinite and chlorite figure in that order of relative abundance.

The geotechnical properties of the silts and clays of both formations are generally similar. However, the plasticity of the Claygate Beds tends to decrease somewhat from the lower to the upper division and the range of plasticity is greatest in the upper division. This may be due to the greater variation in quartz content and montmorillonite content in the latter division than in the two others. The clays in both formations tend to have normal activity whilst that of the silts is both normal and active.

The values of the undrained shear strength parameters, especially in the sandy material, are influenced by the amount of cement present, and the degree of interlocking of grains and the degree of compaction. The undrained shear strength of the silts and clays suggests that they range from soft to very stiff.
Discussion of ‘Influence of rainfall intensity and duration on slope stability in unsaturated soils’ by C. W. W. Ng & Q. Shi (Quarterly Journal of Engineering Geology, 31, 105–114)
Authors: McDougall J. , Ng C. W. W. , Shi Q.
Published: November 2007

J. McDougall writes: The authors have presented a numerical study of the influence of rainfall infiltration on unsaturated slope stability. This type of approach can provide insights into the process of infiltration and has potential as a predictive tool but its usefulness is dependent on a realistic representation of the actual groundwater conditions. One area of difficulty, which can undermine the simulation exercise, is the interpretation of boundary flows.

In the case presented, the authors state that vertical boundaries FG and HI in Fig. 3 have prescribed hydraulic heads and boundary GH is impermeable. Infiltration due to rainfall is applied to boundary FI. It is, however, unclear whether this is applied over the entire exposed upper surface or some subsection of it. Since the vertical boundary heads are prescribed, any rise in main ground- water table due to applied rainfall, particularly if it is applied over the entire exposed surface, would be constrained by these boundary conditions. Are the authors able to comment on this and their conclusion that the main water table is not significantly affected by the different rainfall events considered?

The adjustment of a hydraulic regime to a prescribed boundary flow is something which may be usefully explored using an unsaturated flow model. Figure 5, which presumably reports the hydraulic conditions at the end of the 24-hour infiltration period, shows recurvate suction profiles at section C-C. Are these an indication of an advancing wetting front (especially in the case of the higher rainfall intensity) and not, as
Characterization of weathered volcanic rocks in Hong Kong
Authors: Irfan T. Y.
Published: November 2007

The mineralogical and fabric characteristics of weathered volcanic rocks, which are widespread in Hong Kong, are poorly documented. Consequently, the significant variations commonly observed, even at the same locality, in engineering properties and
in situ
behaviour of these rocks and the resulting soils cannot be adequately related to their basic mineralogical and fabric characteristics. A model for weathering of volcanic rocks, particularly those of pyroclastic origin, is presented in this paper. Modifications, similar to those recently proposed for granites by Irfan, are proposed to the material and mass weathering schemes commonly adopted in Hong Kong for the characterization of weathered volcanic rocks in engineering use. The appropriateness of various proposed petrographic and chemical weathering indices to generally fine-grained volcanic rocks is examined. A number of modifications are proposed to the standard soil preparation and testing methods for the soils formed from tropical weathering of volcanic rocks in order to obtain meaningful and more repeatable results.
A note on the estimation of permeability of granular soils
Authors: Trenter N. A.
Published: November 2007

Three methods are frequently adopted to measure the permeability of granular soils: determinations made on the basis of the soil's particle size distribution; on the results of
in situ
rising or falling head tests; and on the results of
in situ
pumping tests. The paper presents the results of permeability tests made using these three methods on granular soils during investigations for the construction of the Nigg Bay fabrication yard, Cromarty Firth. Of the methods based on particle size distribution, the one due to Masch & Denny was found to give results closest to the pumping test values. Permeabilities calculated using Hazen's rule were significantly higher than the pumping test results, while those calculated from the results of
in situ
falling head tests were significantly lower. On the basis of the results presented, there would appear to be a case for the adoption of a method such as Masch & Denny's for permeability estimation of granular soils.
Environmental hazards of unplanned urbanization of mountainous terrains: a case study of a Himalayan town
Authors: Anbalagan R.
Published: November 2007

Unplanned and non-systematic construction activities including road and building have been a major cause of environmental degradation in hilly terrains. Ill-conceived human urbanization over preciptous and critically stable hill slopes developed on geologically weak rock formations has often contributed to the instability of the slopes. The paper deals with impacts of human encroachment on the fragile ecological balance of Nainital, a famous hill resort of the Kamaun Himalaya, and discusses a scheme of mitigation measures to prevent further degradation of the environmental stability of the region.
Time Prediction of a Rock Fall in the Carnic Alps
Authors: Glawe U. , Zika P. , Zvelebil J. , Moser M. , Rybar J.
Published: November 2007

Based on an extensive field study and on the long-term monitoring of the kinematics of a toppling rock tower standing on a slope edge, a forecast of the time of its failure is presented. This is derived from a consideration of both present static equilibrium of the rock block including its kinematics and phenomenological characteristics and also the stage of disintegration of the block as part of the processes leading to rock fall.
Reversal shear box test for Hong Kong saprolitic soils
Authors: Au S. W. C.
Published: November 2007

The problem of material variability is a major difficulty in the determination of shear strength parameters for Hong Kong saprolitic soils. To obtain the parameters for slope design through direct shear testing, single samples can be used to overcome the problem if the ‘reversal’ shear box is employed. Such a method is explored and discussed in this Technical Note.
Abandoned mineworkings in chalk: approaches for appraisal and evaluation
Authors: Smith G. J. , Rosenbaum M. S.
Published: November 2007

An outline scheme is proposed for the appraisal of stability of abandoned mine workings in chalk, comprising a preliminary study, a practical appraisal and an evaluation. Those factors which define the pre-mining geological context are identified and their interaction discussed. A conceptual model for the potential deterioration of a mine is presented in terms of the processes which might occur. Outcomes, leading to some form of surface collapse, will depend on a measure of continuity of the various different constituent processes. Geographical information systems (GIS) are used for the evaluation. Their application is of particular benefit where an engineering classification scheme needs to be established.
Building stone: the geological dimension
Authors: Jefferson D. P.
Published: November 2007

Although the location, planning and operation of building stone quarries is similar in many respects to other industrial minerals, the scale of the operation and the methods used for stone extraction result in significant differences. Restoration and conservation techniques have rarely taken very much account of the petrology of the material to which they were applied. This is now changing. The complex chemical, mineralogical and biological changes involved in the weathering of stone demand a contribution from a multi-disciplinary team working on our cultural property.
The influence of granular calcareous particles on the residual shear strength of Fuller's Earth Clay
Authors: Hawkins A. B. , McDonald C.
Published: November 2007

Decalcification is proposed as a cause of the continued movement observed in many natural and engineered slopes in calcareous mudrock formations. It is deemed that such movement may potentially occur as granular calcareous particles, which otherwise maintain high residual shear strengths, are leached from shear surfaces within slipped masses, changing the mode of residual shear from transitional to sliding. Measurements of the residual shear strengths of 42 natural samples taken through the Fuller's Earth succession near Bath over a range of effective normal stresses emphasize the curved nature of many failure envelopes. The results demonstrate that the threshold between the two modes of shear occurs at approximately 25% calcite content. Fuller's Earth Clay with more than 25% calcite content is thus prone to significant decreases in residual shear strength upon partial or total decalcification.
Groundwater resources, their development and management in the UK: an historical perspective
Authors: Downing R. A.
Published: November 2007

The Water Act of 1945 can be considered to mark the beginning of modern quantitative hydrogeology in the UK. It introduced a period of some 20 years during which the assessment of resources was the dominant issue as groundwater was developed to meet the increasing post-war demands.

The significant effect that groundwater abstraction had on river flows was one of the reasons for the Water Resources Act of 1963. This legislation made regional groundwater management, with the river basin as the basic unit, a practical objective. From 1974, the degradation of groundwater quality and the risk of pollution increasingly became the main issue.

Groundwater resources of England and Wales provide 350f public water supplies. About 300f the infiltration to the main aquifers of the Mesozoic and Cenozoic is abstracted. The use of groundwater has increased by 80ince 1948 when data first became available.

Groundwater is now seen as a regional resource developed within the sophisticated water resource systems that are necessary for effective river basin management. Development must consider all demands on an aquifer including not only water supply but environmental aspects such as maintaining river flows and wetland environments.
Enfield-Haringey artificial recharge scheme
Authors: Baxter K. M. , O'Shea M. J.
Published: November 2007

Artificial recharge was carried out experimentally in north London by the Water Resources Board and the Metropolitan Water Board between 1953 and 1970(Boniface 1959). These trials were successful, although only small volumes of water were recharged. Research by Thames Water Authority continued between 1975 and 1984 at a larger scale in the north London area (Flavin & Hawnt 1979; Flavin & Joseph 1983).

Thames Water Utilities drilled and tested 14 new production boreholes for the Enfield-Haringey Scheme along the course of the New River in north London (Fig. l, opposite). These new boreholes, together with nine existing sites, are designed to increase the strategic groundwater resources of north London by 90 Ml/d by artificially recharging the Chalk and Thanet Sands aquifer beneath London (O'Shea 1994).

During an average year, demand for water is often lower than that available from the Coppermills Water Treatment Works and between 10 and 20 M1/d of this excess fully treated water can be gravity recharged to the aquifer. This will be by low-rate, trickle recharge ensuring that the volume of water stored in the aquifer is sufficient to sustain a prolonged drought abstraction for up to 200 days. When demand for water is high, as in drought conditions, groundwater can be pumped from the aquifer, using the same boreholes, directly into the New River which acts as an aqueduct taking the water back to Coppermills, via the East Reservoir at Stoke Newington for treatment and supply. The scheme will be used strategically in times of
Topples on underdip slopes in the Highwood Pass, Alberta, Canada
Authors: Cruden D. M. , Hu Xian-Qin
Published: November 2007

Sixteen topples up to 15 m thick are exposed on underdip slopes in the Highwood Pass, Alberta. Topping modes are controlled by ratios of joint spacings to bedding thicknesses (block rations), rock strenght and topography, Block flexure topples occur where block ratios are less than 2, while block topples form where block ratios are larger than 2. multiple block topples develop sliding surfaces which may fracture thin beds rather than follow discontinuities. Chevron topples are retrogressive, simple block topples whose rupture surfaces coincide with hinge surfaces which may also develop into sliding surfaces. Chevron topples form on slopes over 35° and are typically less than 5 m thick. The development of sliding surfaces during block toppling may allow the displaced masses to become slides.
Undulatory extinction of quartz in some British granites in relation to age and potential reactivity
Authors: Graham West
Published: November 2007

The undulatory extinction of quartz has become important in engineering geology because of its supposed indication of an alkali-silica reactive aggregate. In an earlier paper (West 1991) it was suggested that, for granites from a single orogenic region, the undulatory extinction angle of the quartz in the rock may be proportional to the age of the rock. The paper showed that this was true for granitic rocks. The paper showed that this was true for granitic rocks from the Chilean orogenic belt (de Hills & Corvalan 1964) and went on to suggest that it would be worthwhile to undertake a study of the undulatory extinction angle of quartz in British granites. This study has now been carried out by research at Leicester University, working on a project sponsored by TRL, the full results of which have been reported elsewhere (Smith & Dunham 1992). This Technical Note discusses two aspects of these results, namely undulatory extinction angel in relation to geological age and potential reactivity.

Undulatory extinction

There are two methods of measuring undulatory extinction on the ordinary flat stage of a popalarizing microscope. The first is that used by De Hills & Corvalan (1994) and is simply tha angle between the first appearance and last disappearance of the extinction shadow in the quartz grain. The second is that proposed by Dolar&Mantuani (1983) which, in addition, involves measuring the first and the last positions of maximum extinction. The two methods are:

De Hills & Corvalan

Appearance of first extinction shadow
A
Geotechnical aspects of sabkha at Jubail, Saudi Arabia
Authors: James A. N. , Little A. L.
Published: November 2007

A large industrial complex was planned to be sited at Jubail on the Gulf Coast of Saudi Arabia. The sabkha here is essentially a near sea level, fiat area of fine grained soils, partially cemented by salt (sodium chloride) and calcium sulphate. Very little carbonate was found. The rest of the site was covered by sand dunes which, further inland, reached a height of 30 m.

The presence of artesian water, detected and measured at widespread locations, probably conducted through fissures in the underlying Hadrukh bedrock, was a particularly note-worthy feature of the area, having an important influence on the design of foundations and submerged structures of which examples are given. The artesian condition has been reported by a few observers for other sabkha areas. Jubail sabkha does not appear to conform in other ways with conditions at other sabkhas; for example, no traces were found of algal filaments, nor does it fit currently accepted ideas of formation or classification.

At Jubail, numerous site investigation boreholes were sunk to assist the design of installations. Measurements in many of these boreholes showed artesian heads, some up to 6 m or more above ground level in sabkha areas and up to 15 m above sabkha level in dune areas. Analyses have been developed in the paper to give rates of upward flow and limits of rise of artesian water in sabkha areas.

For construction reasons, sabkha was covered with 1.5 m to 3 m of compacted dune sandfill; further evidence for the underlying artesian condition was the discovery (predicted by the authors) of the rise of groundwater above the original ground surface and into sandfill. Calculations gave average rates of rise between 0.2mm/day and 1 mm/day. These artesian conditions are believed to receive a significant contribution from the sand dunes where high water tables have been recorded. Ideas have been put forward which could form a basis for a revised theory of the origin and continued existence of sabkhas at Jubail and at other similar locations.

The influence of artesian water on the design of installations at the industrial complex is discussed.
The estimation of rock rippability
Authors: MacGregor F. , Fell R. , Mostyn G. R. , Hocking G. , McNally G.
Published: November 2007

This paper presents the results of research into the rippability of rock by bulldozers carried out at the University of New South Wales. A database of detailed ripping and geological data gathered from highway and mine sites in New South Wales, Australia, has been used to determine the influence of different factors on the ripping productivity of bulldozers. The dominant factors affecting productivity have been found to be the unconfined compressive strength of the rock, the degree of weathering, seismic velocity, joint roughness and strength and the spacing of joints and bedding in the unripped rock, and bulldozer mass. The database has also been used to assess several commonly used rippability prediction methods. These are shown to be generally poor predictors of both ripping productivity and difficult ripping conditions. The forces involved in ripping have been measured in the laboratory on a quarter scale model of a tine, and in the field on an instrumented full scale tine, and the relationship between force and unconfined compressive strength and depth of penetration of the tine determined. Using this information, and a multiple variable regression analysis of the database, a method has been proposed for estimating productivity and for identifying difficult ripping conditions. This paper presents the method used to gather information for the database, the results of analysis of the database to assess the influence of individual factors on ripping productivity, a review of the available methods for predicting rippability, the results of multiple variable regression analysis, and the proposed prediction method.
Editorial
Authors: West Graham
Published: November 2007

The Editorial Board is pleased to announce that the Young Authors' award for 1994 has been won by Dr Paul Younger of Newcastle upon Tyne University for his paper ‘Simple generalized methods of estimating aquifer storage parameters‘, published in
QJEG
Vol. 26, No 2. The presentation of a cheque and certificate was made at a Hydrogeological Group meeting at Keyworth on 29 March by David Allen on behalf of the Board. Our congratulations go to Dr Younger for his fine award-winning paper.

One of the most important advances in soil and rock mechanics has been a realization of the significance of the non-linear failure envelope: i.e. the consequences that follow from the fact that the envelope to the plot of Mohr circles on the shear stress—normal stress diagram is a curve rather than a straight line. The curved failure envelope is not only more satisfying mathematically, but also allows slope stability calculations to be made more accurately, gives a better insight into the mechanism of slope failure and thereby gives us more confidence in slope design. For all these reasons, therefore, it is gratifying to report that in this Part of the
Quarterly Journal of Engineering Geology
we have a major paper by Perry on the subject. It gives a technique for defining non-linear strength envelopes and shows how they can be incorporated in slope stability analysis. The paper is, of course, complete in itself, but for those readers who wish to try out the technique described for themselves, the
Mechanism of creep in a volcanic saprolite
Authors: Irfan T. Y.
Published: November 2007

Clay mineralogy, mass structural features (e.g. relict discontinuities) and human activity all contributed to the initiation and retrogression of a creep-type instability in a saprolitic soil of volcanic rock origin at a landslip site in Hong Kong. Continuous creep resulted in the formation of a shear surface in the saprolite which then acted as a sliding surface when the slope was undercut. Shear zones have rarely been reported in saprolitic soils.
The morphology, geometry and kinematics of Judgement cliff rock avalanche, Blue Mountains, Jamaica, West Indies
Authors: Maharaj Russell J.
Published: November 2007

Judgement Cliff rock avalanche (JCRA) occurred during the latter part of 1692, during which 131-181 x 10
6
m
3
of faulted Miocene white limestone with chert nodules and minor sandstones and mudrocks, on a 38° overdip slope was detached on the eastern bank of the Yallahs River near Llandewey. The rock mass failed by a combination of sliding, free fall and toppling, impacted and disintegrated near the base of the original slope and flowed downslope subsequently damming the Yallahs River. Seismic loading followed by high water pressure in clefts are thought to be the main triggers for the event. The debris travelled horizontal and vertical distances of 1.763 km and 0.44 km respectively, accumulating over an area of 1.09 x 10
6
m
2
. The height/length and depth/ length values, hummocky surface topography and highly disintegrated nature of the deposit suggests that it was emplacement by flow of relatively dry debris.
The Franklands Village landslide
Authors: Morris Stevenson
Published: November 2007

Between 23 December 1993 and 5 January 1994 a major landslip movement developed in Franklands Village which is situated on the eastern side of Haywards Heath, West Sussex. The approximate Ordnance Survey map reference is TQ 342/236.

The site of the landslide is set on the eastern slopes of a north-south trending valley. The existing development comprises blocks of two-storey fiats and semi-detached houses. The development for the Franklands Village Housing Association (FVHA) was constructed in the 1930s.

A development comprising a block of two-storey sheltered housing (Charles Bennett Court) was constructed by the Hanover Housing Association between 1991 and 1992, on the higher valley slopes to the southeast of the landslide.

Southern Testing Laboratories Limited (STL) were called in by Messrs K. A. Marshall & Partners, Consulting Engineers to the FVHA, to investigate cracking and foundation movement that had been developing in the Franklands Village properties during December 1992.

In general terms the valley slopes fall towards a small stream, towards the northwest at overall slopes of between 13 and 16° . Terracing, carried out to facilitate the initial development, steepened locally to between 30 and 45°. An investigation comprising hand-excavated trial holes, shell and auger boreholes (using a specially adapted restricted access rig), piezometers, slip indicator and monitoring of surface reference stakes, laboratory testing and geological and engineering analysis was undertaken by STL between January and April 1993.

The solid geology comprises the Upper Tunbridge Wells Sands at the crest of the slope, overlying the clays of the
An unfamiliar alkali-aggregate reaction from Trinidad
Authors: Eglinton, M. S. , Higginbottom I. E. , Pettifer G. S.
Published: November 2007

Blemishes rapidly developed on the surface of freshly poured structural concrete in Trinidad. The affected concrete was unsightly and suffered some loss of strength. Laboratory investigations showed that apparently inert natural sand and gravel aggregates used in the concrete were in fact coated or impregnated with an organic-iron complex which could be mobilized by cement alkalis to stain the concrete and retard the hydration of the surrounding cement. The reaction occurred when the total alkali content of the cement exceeded about 0.500y mass, expressed as Na~O equivalent. Lithologically similar aggregates from a neighbouring deposit were found to be predominantly non-reactive. When these were substituted for the original source, there was no recurrence of the problem. This paper describes the procedures which were used in the investigations, and discusses the character and occurrence of the alkali-reactive material. A simple test is suggested for the identification of aggregates which might react in this way. The authors are not aware of any published account of this reaction, although similar environmental factors might occur widely in tropical regions.
Technical Note Hydraulic conductivity of a tropical residual soil prone to landslides
Authors: Bronders J.
Published: November 2007

Saturated hydraulic conductivity or the coefficient of permeability (κ) of a residual soil prone to landslides was determined for a study area in Fiji. The techniques used were not new but the approach and the resulting κ-values may be useful for other studies (e.g. landslides). Inverse auger-hole tests are used to estimate κ-values. Tests conducted in sandy silty soils indicate values in the order of 10
-6
ms
-1
. No significant difference was found between calculated values at the surface and at 3 m depth. Infiltration tests showed saturated infiltration rates of 10
-5
ms
-1
.
Geotechnical properties of the Pleistocene clays of the Pappadai Valley, Taranto, Italy
Authors: Cotecchia F. , Chandler R. J.
Published: November 2007

This paper presents a set of experimental data that characterizes the Lower Pleistocene Pappadai Blue Clay in the Pappadai Valley, Taranto, southern Italy.

Basic geotechnical classification data are given, along with the results of chemical and mineralogical analyses which describe the variations of the properties of the clay for various vertical profiles through the deposit. These results reflect the near complete history of a sedimentary basin, add to the database for the blue clays of the Apulian Region, and provide a full description of the distribution of properties of a blue clay deposit. The variations of the properties of the clay can be related to the depositional history, to micropalaeontological studies, and to weathering process subsequent to deposition. The microstructure of the clay is studied using a scanning electron microscope.

Of particular interest are the relationships between the geological history of sedimentation, which is known with reasonable accuracy, and aspects of the mechanical behaviour of the clay.
Forms of hydraulic fractures created during a field test in overconsolidated glacial drift
Authors: Murdoch L. C.
Published: November 2007

Hydraulic fractures as long as 13 m were created at depths of 2 m in overconsolidated silty clay glacial drift during a field test using equipment designed to create hydraulic fractures in oil wells. The vicinity of each fracture was excavated, typically revealing a continuous fracture whose geometry was defined by four zones: a vertical fracture adjacent to the parent borehole; a flat-lying fracture in the vicinity of the borehole; a gently dipping fracture that assumes a preferred direction of propagation away from the borehole; a vertical fracture that intersects the ground surface. The hydraulic fractures were gently dipping with a preferred direction of propagation that apparently was controlled by loading of the ground surface; the fractures propagated away from a back hoe parked next to the parent borehole. Sand pumped into some of the fractures formed permeable layers that could increase flow into or out of low-permeability soils or rock, suggesting that sand-filled hydraulic fractures could have a variety of geotechnical or environmental applications.
The investigation of dissolution subsidence incorporating microgravity geophysics at Ripon, Yorkshire
Authors: Patterson D. A. , Davey J. C. , Cooper A. H. , Ferris J. K.
Published: November 2007

Dissolution subsidence affords some of the most difficult ground conditions with which engineering geologists have to deal. Within the UK, areas underlain by gypsiferous Permo-Triassic strata, most notably around Ripon in Yorkshire, are prone to dissolution structures and resultant building failures are well documented.

Conventional drilling of such unstable sites is often a ‘hit and miss’ affair and most geophysical techniques do not provide sufficient resolution to offer adequate confidence in the results. Proposals for the redevelopment of a site within the urban area at Ripon could not rely on such frequently inconclusive methods and it was necessary to implement a phased approach to site investigation. Following a desk study, high-resolution microgravity geophysics was carried out both inside and outside the existing building. This indicated a major negative anomaly of peak amplitude -74 μGal. Subsequent static core probing, rotary drilling and trial trenching confirmed the existence of a potentially unstable breccia pipe which could therefore be taken into account in the engineering design.
The genesis of the brown boulder clay of Dublin
Authors: Farrell Eric R. , Coxon Peter , Doff David H. , Prieďhomme Laurent
Published: November 2007

This paper presents the results of a study into the physical, chemical and mineralogical composition of two glacial sediments in Dublin, Ireland which are colloquially called Dublin ‘brown’ and ‘black boulder clays’. The objective of this study was to ascertain whether the ‘brown’ was formed through weathering of the ‘black boulder clay‘ or whether it represents a depositional feature. The study included fabric, clast lithological and microscopic analyses as well as X-ray diffraction. This work has shown that the sedimentology and fabrics of both are of the same glacigenic origin and that the lithology and mineralogy are identical apart from oxidation of the clay particles in the ‘brown’. It is therefore concluded that the ‘brown boulder’ clay arises from the weathering processes affecting the upper levels of the ‘black boulder clay’. This finding is consistent with the differences in the geotechnical parameters.
A geoteehnical survey of phase 1A of the Lesotho Highlands Water Project
Authors: Bell F. G. , De Graaf P. J. H. , Haskins D. R.
Published: November 2007

The purpose of Lesotho Highlands Water Project is primarily to supply water from Lesotho to the Pretoria-Witwatersrand-Vereeniging industrial region of South Africa. In addition, the hydroelectric scheme at Muela will supply enough electrical power to meet the needs of Lesotho.

The project consists of a number of dams, reservoirs and tunnels, and a hydroelectric scheme which will be constructed in four phases. Construction operations, if the project runs to completion, will last until around 2020. Phase IA commenced in 1987 and consists of the Katse Dam, a Transfer Tunnel from the impounded reservoir to Muela hydroelectric power station, the Muela Dam, and a Delivery Tunnel from the latter dam to the outfall on the Ash River, which is part of the Vaal River system. The tunnels total some 81 km in length.

The Katse Dam and Transfer Tunnel are constructed in the basalts of the Drakensberg Formation. Many of these basalts have been subjected to deuteric alteration and consequently contain expansive clay minerals. Their presence can mean that the basalts disintegrate rapidly on exposure, which has led to increased excavation at the dam site, and slabbing and spalling from the perimeter of the tunnel. The Delivery Tunnel South was constructed in sandstones of the Clarens Formation. These sandstones presented few problems during excavation and this tunnel was bored 20 months ahead of schedule. It was anticipated that the Delivery Tunnel North would be the most difficult to excavate as it runs through a succession of mudstones and sandstones. Hence this tunnel is being excavated by a double-shielded tunnel boring machine which can bore through varied ground and provide protection against rock falls, while simultaneously installing precast lining segments.
Effect of stiffness and amount of reinforcement on strength of sand
Authors: Al-Omari Raid R. , Nazhat Yahya N. , Dobaissi H. H.
Published: November 2007

High-quality geosynthetics of high-stiffness materials are being increasingly used in developing countries although they are not always readily available. An alternative approach in some situations is to use a larger amount of low-stiffness reinforcement. Triaxial tests have been performed on plastic mesh reinforced sand. The sand density, mesh stiffness and the number of reinforcing layers were varied. From these tests it was concluded that there may be a limiting reinforcement stiffness, influenced by the number of reinforcing layers after which there will he no further gain in strength. The density of sand reinforced using plastic mesh is found not to control strongly the strength. The results also revealed that the use of multiple layers of low-quality material can be more effective than the use of fewer layers of high-stiffness reinforcement.