021973   Jalan S (NO, Government P.G. College, Dausa, Rajasthan, Email: seemajalan1@gmail.com) : Comparison of visual interpretation and object based classification techniques for urban land cover mapping, using high resolution. Trans Inst Indian Geogr 2010, 32(2), 167-82.

Information extraction of urban areas from very high resolution satellite images requires methods which can incorporate spatial, textural and contextual information content of the image in the classification process along with the spectral characteristics of the pixels in a multi-scale environment. This approach is effectively followed in visual interpretation and is the fundamental basis of object based image analysis technique. This paper compares the performance of visual interpretation and object based classification for land cover mapping of two representative types of urban landscapes using merged CARTOSAT-1 and IRS-P6 LISS-IV datasets. For object based classification nearest neighbour technique has been applied. Comparison is based on rigorous qualitative and quantitative measures of evaluation. The results revealed that comparable classification accuracies can be achieved by both the methods for land cover mapping of dense urban as well as sub-urban fringe areas. Both the methods confront with difficulty in differentiating classes with indistinct image characteristics. Visual interpretation allows for effective integration of prior knowledge. Nevertheless, derived accuracies are conditioned by limitations of human vision and complexity of landscape. Object based classification technique has proved to be a fast, versatile and objective means of producing visually appealing outputs in a semi-automated manner with very close approximation to results obtained by visual interpretation approach. It can effectively be used for time effective extraction of land cover information in complex urban landscapes for such applications where concern is class area and high cartographic quality of boundaries is not required.

6 illus, 4 table, 13 ref

021972   Hangaragi S S (Geography Dep, S.R.N. Arts and M.B.S. Commerce College, Bagalkot-587 101, Email: sshangaragi@rediffmail.com) : Measurement of agricultura efficiency and planning for sustainable development in drought prone area: a case study of Bagalkot district of Karnataka. Trans Inst Indian Geogr 2010, 32(2), 127-36.

The study of agricultural efficiency is one of the major concerns of agricultural geographers and agricultural economists. A study of the spatial variations in agricultural efficiency is indispensable for differentiating areas of poor performance from the other more productive area. In this paper an attempt is made to analyses the spatio-temporal variations in agricultural efficiency of Bagalkot district during 1995-96 and 2005-06. In the study region, three taluks (Hunagund, Bagalkot and Badami) was noticed as low efficiency regions in 1995-96, but in 2005-06 four taluks were noticed, they are Bagalkot, Badami, Hunagund and Bilagi. In the medium efficiency regions Bilagi and Mudhol taluks were recorded in 1995-96, but in 2005-06 only one taluk were noticed i.e., Mudhol. In high efficiency region only Jamkhandi taluk was recorded in both the study period. On the basis of results, it can be concluded that the agricultural efficiency in Bagalkot district is an advancement, due to diversified nature of land-use pattern and cropping pattern of the Bagalkot district, has increased the production capacity and cropping intensity of the land. In the present scenario needs to strengthen the irrigation facilities, soil and moisture conservation, adoption of bio-technology, afforastation, changing in the cropping pattern, agronomic practices, livestock development, rural communications, development of medium, small and marginal farmers, agricultural laborers and setting up agro-based industries. The dry land development program, sustenance of animal husbandry, fisheries, horticulture, sericulture and small scale industries at village level should be setup through the various programmes for sustainable development of agriculture sector. Therefore, plans on permanent basis to promote agriculture development and restore the ecological balance in the region.

1 illus, 3 table, 10 ref

021971   Haldar A (NO, University of Arizona, Tucson, AZ 85721, USA) : Is the inverse problem technique appropriate for structural health assessment?. Curr Sci 2009, 97(8), 1187-95.

Structural health assessment techniques using system identification-based approaches have recently generated a considerable amount of multidisciplinary research interest. However, in 1979, it was stated that the inverse transformation technique could not identify a system with measured response information. Presence of many sources of error including noise, high frequency content, slope, DC bias, etc. in the measured response information were considered to be the major reasons. However, removing these sources from the measured responses may not be adequate to eliminate the non-convergence problem. In this article, it is conclusively demonstrated that a system can be identified if the amplitude and phase shift errors embedded in the measured responses are mitigated properly. The noise may not be the primary reason for the non-convergence. The conclusions made here are primarily based on the analytical and experimental works completed by the author and his team. Their experience indicates that the system identification-based structural health assessment techniques have unlimited application potential.

5 illus, 3 table, 20 ref

021970   Guha A;Vinod Kumar K;Lesslie A (Geosciences Division, National Remote Sensing Centre, Indian Space Research Organisation, Hyderabad-500 625, Email: arindam_iit@rediffmail.com) : Satellite-based geomorphological mapping for urban planning and development a case study for Korba city, Chhattisgarh. Curr Sci 2009, 97(12), 1760-5.

Geomorphology is an important aspect which guides immensely in urban planning. Mapping of geomor-phology not only gives an idea about the variations in landscape but also indirectly facilitates in evaluating the resources of an area. Present study shows the capability of satellite data in delineating major geomor-phological units in an industrial area like Korba city. It has also been observed that geomorphological maps along with other relevant terrain-related information such as lithology and geological structures can delineate few important zones; each of these zones is suitable for specific type of urban development and planning. This communication highlights how a simplistic approach like logical integration of geomorphological and geological information can provide valuable inputs for urban planning and development.

7 illus, 2 table, 5 ref

021969   Dutta S;Pradhan R (Environmental Studies Dep, Maharshi Dayanand Saraswati Univ, Ajmer-305 009) : Analysis of ground water quality of areas adjacent to loco and carriage workshops, Ajmer, Rajasthan. Ecol Envir Conserv 2009, 15(2), 265-8.

Water is elixer of life. Water makes up more than two thirds of the weight of the human body. It is important to the mechanics of the human body. People can survive days, weeks or months without food, but only about four days without water. There has been a serious concern over the quality of water resources. The World Health Organization (WHO) estimates that 80% of all sickness in the world is attributable to unsafe water. Water may get impurities of various kinds from ground or soil with which it comes into contact it may also get contaminated with sewage and industrial wastes. The quality of water can be determined by detecting its physico-chemical properties. The present study involves ground water analysis of selected regions of Ajmer city. Samples were taken from hand pumps situated in 18 different localities adjacent to Loco & Carriage Workshops of the city, mainly used for drinking purpose. Loco & Carriage Workshops are the oldest workshops of Indian Railways. At present complete maintenance work for diesel locomotives, coaches and wagons is carried out in these workshops. About 9500 workers are employed in these workshops. The area around the workshops is also densely populated. Several physico-chemical parameters including pH, electrical conductivity, total dissolved solids, total hardness, salinity, chloride, sulphate, nitrate, sodium and fluoride were studied. The study indicates slight alkaline nature of ground water samples. TDS and total hardness values were observed higher than permissible limit. While sulphate and nitrate values were observed within the permissible limits as prescribed by WHO. The correlation coefficient showed significant relationship of pH with TDS, calcium hardness and sodium, potassium and fluoride concentration in ground water. EC shows significant effect on TDS. Statistical analysis also reveals significant effect of chloride content on alkalinity of ground water and that of Mg on hardness of water whereas chlorides shows a positive significant relationship with sulphate and sodium with potassium content in ground water. Except some selected sites, ground water is grossly suitable for domestic purposes.

3 tables, 6 ref

021968   Duraiswami R A (Geology Dep, Pune Univ, Pune-411 007, Email: raymond_d@rediffmail.com) : Pulsed inflation in the hummocky lava flow near Morgaon, western Deccan volcanic province and its significance. Curr Sci 2009, 97(3), 313-16.

^ssc4 illus, 1 table, 18 ref

021967   Dikshit J K (NO, , 3, Salil Apts, Sanewadi-Aundh, Pune-411 007, Email: rvdikshit@vsnl.com) : Some catastrophic events during the summer monsoon season 2010, in Asia. Trans Inst Indian Geogr 2010, 32(2), 217-24.

4 ref

021966   Champati Ray P K;Parvaiz I;Jayangondaperumal R;Thakur V C;Dadhwal V K;Bhat F A (NO, Indian Institute of Remote Sensing, Dehradun-248 001, Email: champati_ray@iirs.gov.in) : Analysis of seismicity-induced landslides due to the 8 October 2005 earthquake in Kashmir Himalaya. Curr Sci 2009, 97(12), 1742-51.

Widespread landslides were reported in the devastating earthquake of 7.6 Mw that occurred on 8 October 2005 with epicentre located within Hazara syntaxis, Kashmir Himalaya. As this area covers mostly inaccessible mountainous terrain, an attempt was made to detect and map landslides on medium to high resolution satellite data products such as Indian Cartosat-1 (PAN: 2.5 m resolution), Resourcesat-1 (LISS IV: 5.8 m multi-spectral), Landsat-TM (30 m multispectral) and ASTER (15 m multispectral). The extent of slope failures and landslides was mapped (776 landslides) based on subpixel registration, image interpretation and field investigation. The ground deformation cum damage survey revealed that the hanging wall side of the causative fault was severely affected and caused numerous earthquake-triggered landslides. The terrain parameters such as surface geology, slope gradient, slope aspect, curvature and relief classes were correlated with actual landslide occurrences and critical classes were identified. The statistical analysis of landslides inventory based on probability density function enabled estimation of earthquake magnitude and size of the largest landslide, which correspond well to the actual data. The study demonstrated extrapolation of total landslide affected area (67.36 km²) from the partial inventory of landslides based on satellite image interpretation. Based on the volumetric estimation, average landslide thickness was determined to be around 6.9-7.7 m and total displaced mass available for erosion was also estimated to be around 0.34-0.52 km³.

6 illus, 2 table, 28 ref

021965   Borah A C (Geography Dep, Nazira College, Sibsagar, Assam) : Impact of small scale tea cultivation on rural economy: a case study of small tea growers of Sivasagar district, Assam. Trans Inst Indian Geogr 2010, 32(2), 119-25.

In Assam, the small tea cultivation is in an infant stage considering the 160 years old tea industry of the country. The small tea growers have come up in recent years to takes up tea cultivation in individual holdings in Assam. Within a short period of last two decades, small tea cultivation ushered in to an era of evolution brining a long term socio-economic changes in the rural areas of Assam. It has been noticed that during the last decade small tea cultivation has started making inroads among the farmers of Assam. This has made significant contributions to the development of rural economy of Assam. It has changed the surrounding natural environment as well as economic activities of the people directly or indirectly. The small tea cultivation has also created a shift in occupational structure to cash crop. There is a definite shift in cultivation pattern from only rice and cereal crops to cash crop. It has also greatly contributed in changing the socio-economic development of the region. An attempt has been made in this paper to study the present status of small tea cultivation and its impact on rural economy ofSivasagar district, Assam.

2 illus, 3 table, 15 ref

021964   Bhattacharyya R;Majumdar T J (NO, Institute of Seismological Research, Gandhinagar-382 009, Email: tjmajumdar@rediffmail.com) : Bathymetry prediction over a part of the Bombay high in the western offshore using very high resolution satellite gravity data. Curr Sci 2009, 97(8), 1152-61.

Bathymetry, when convolved with a response function, yields geoid or gravity. The predictive model as computed using high-resolution satellite gravity, and its downward continuation, is a generalized approach and seems to be satisfactory for bathymetry prediction in a complex region. The predictive model has been modified and applied over the study area in the western Indian offshore using very high resolution satellite gravity data (data gap ~4 km) as obtained from Geosat, Seasat, ERS-1/2 and Topex altimeter data. The area consists of variable bathymetric features, e.g. ridges and trenches, and it has been found to be successful to detect more number of features in comparison to those obtained from the presently available bathymetry data. Results from the predicted model have been compared with ETOPO2, NHO ship-borne and GEBCO bathymetry data and have been found satisfactory for geophysical and oceanographic applications.

5 illus, 2 table, 37 ref

021963   Ahuja D R;Srinivasan J (National Institute of Advanced Studies, Indian Institute of Science, Bangalore-560 012, Email: dahuja@nias.iisc.ernet.in) : Why controlling climate change is more difficult than stopping stratospheric ozone depletion. Curr Sci 2009, 97(11), 1531-4.

2 table, 16 ref

020913   Ude FF;Nwanl C D (Fisheries and Aquaculture Dep, Ebonyi State University. P.M.B. 053, Abakaliki. Ebonyi Nigeria) : Correlation characteristics of the limnological properties of Ebonyi river, Nigeria. Ecol Envir Conserv 2009, 15(2), 201-4.

Analysis of major limnological properties of Ebonyi River, a tropical freshwater system was carried out between September 2006 to February 2008 to establish the correlation among parameters and to generate fundamental data on the system for inferential deductions. Parameters measured were Fish abundance, Temperature, Transparency, Water depth, Dissolved Oxygen, Carbondioxide, pH, Biochemical oxygen demand, Total dissolved solids.Total Alkalinity, Conductivity, Nitrite-Nitrogen, Nitrate-Nitrogen and Phosphate-Phosphorus.The Data were analysed using Spearman rho's SPSS parametric statistical package. Results show that Ebonyi River exhibited unique features typical of a tropical river system. It was concluded that introduction of municipal wastes into the system is capable of altering the limnological status of the river and impair water use and fish production.

1 table, 15 ref

020912   Srivastava P;Shukla U K (NO, Wadia Institute of Himalayan Geology, Dehradun-248 001, Email: pradeep@wihg.res.in) : Quaternary evolution of the Ganga river system: new quartz ages and a review of luminescence chronology. Himalayan Geol 2009, 30(1), 85-94.

The Ganga foreland basin is amongst the largest such basins in the world and has recently been studied by several groups. Considerable confusion on the chronology has been created on account of poorly informed interpretations. We review the existing chronological framework and add new luminescence chronometric data from the Ramnagar section along the Ganga River at Varanasi. This section is dated using the Single Aliquot Regeneration (SAR) on quartz. The age data indicated that the (1) sedimentation of this 20 m thick section started prior to 59 ka and continued at least up to 7 ka (2) ages from five samples are in stratigraphic order and confirm the ages given by Srivastava etal. (2003a) from the same section that were derived using Multiple Aliquot Additive Dose (MAAD) protocol on fine-grained feldspars and quartz (3) Quartz palaeodoses derived are as high as 186±11 Gy that can yield to OSL ages of <126>60 ka and this is in contrast to earlier suggestion of an upper bound of <126>35 ka.

4 illus, 4 table, 35 ref

020911   Singh R B;Singh S;Mandal T N (Botany Dep, Inter College B.M.P-7, Katihar, Bihar) : Studies on water quality of village Parwa Nabtol Madhipura, Bihar. Ecol Envir Conserv 2009, 15(2), 371-2.

Evaluation of different physico-chemical parameters of ground water of village Parwa Nabtol ( Murliganj Block, Madhipura District, Bihar) as carried out to study the water quality of the water samples. Samples were collected from different sources of different locations through out the year 2001. Parameters studied were pH, EC.TDS, fluoride, sulphate, chlorides and nitrates.The water was found to be unfit for drinking.

1 table, 5 ref

020910   Ramkumar M;Anbarasu K;Sugantha T;Rai J; Sathish G;Suresh R (Geology Dep, Periyar University, Salem-636 011, Email: muramkumar@yahoo.co.in) : Occurrences of KTB exposures and dinosaur nesting site near Sendurai, India - an initial report. Ultra Scient phys Sci 2010, 22(3), 573-84.

Occurrences of exposures of Late Maastrichtian-Early Danian rocks are found near Sendurai and Niniyur villages along E- W trending ephemeral streams. These exposures contain multiple levels of three types ofunifonn sized, spherical moulds/casts of presumably unhatched egg precursors of sauropods. Based on the morphological and size characteristics, these moulds/casts are assigned to megaoolithid oogenus provisionally. Each cluster has 7 or 8 moulds al igned circularly. The matrix surrounding these clusters contains typical nanofossil assemblage representative of Latest Maastrichtian. Sediments overlying these clusters, interpreted to be dinosaur nesting sites contain clayey admixture and silty clay/shale deposits that are reported to be weathered products of Deccan volcanic ash. These deposits are followed by bivalve-rich limestones, bioclastic nautilus limestones and calcareous sandstones that are typical of Danian deposits of Anandavadi member of the N iniyur Formation. Preliminary field observations suggest that faunal extinction preceded the Cretaceous-Tertiary boundary (KTB) mass extinction. Further studies are needed to ascertain the paleoenvironmental conditions that contributed to the demise of the dinosaurs. There is an urgent need to preserve this important dinosaur nesting site for geotourism and future studies to understand the geological past.

2 illus, 1 table, 29 ref

020909   Rameshwar Rao D;Rai H (NO, Wadia Institute of Himalayan Geology, Dehradun-248 001, Email: raodr@wihg.res.in) : Geochemistry of granitoids from the shyok tectonic zone near Tangtse, Ladakh, India. Himalayan Geol 2009, 30(1), 35-44.

The Tangtse granite and the associated leucocratic granite dykes from the Shyok tectonic zone have been analyzed geochemically for their source characterization. The Tangtse granites are metaluminous granodiorites with biotite and hornblende as mafic constituents. The studies suggest that the primary melts of the granodiorite were derived from mafic lower-crust reservoir due to crustal thickening associated with arc magma underplating. On the other hand, the leucocratic granite dykes occurring within this granite are two mica granites. These rocks were derived from the partial melting of felsic source such as the Tangtse granite. Such process might have triggered by the frictional heating within the crust as a result of tectonic activity in the region.

10 illus, 2 table, 46 ref

020908   Raghumani Singh Y;Dogra N N;Rathore A (Earth Sciences Dep, Manipur Univ, Manipur-795 003, Email: yengmani@gmail.com) : Record of palynomorphs from the upper murree, Jammu, India. Himalayan Geol 2009, 30(1), 69-73.

The palynomorphs recorded herein for the first time from the Laren bed in the basa) part of the Upper Murrec are stratigraphically significant. They belong to 14 species in 11 form genera, of which 9 species are new. This mioflora) assemblage is dominated by Striatriletes spp., Pinuspotlenites sp., Polypodiaceaesporites sp., Podocarpidites sp., Botryococcus sp. Corrugatisporites sp., etc. It indicates a Late Oligocene-Early Miocene age for the fossiliferous horizon and a swampy (fresh water) depositional environment tropical to subtropical conditions.

2 illus, 48 ref

020907   Mathur N S;Juyal K P;Kumar K (NO, Wadia Institute of Himalayan Geology, Dehradun-248 001, Email: kumark@wihg.res.in) : Larger foraminiferal biostratigraphy of lower paleogene successions of zanskar tethyan and Indus-Tsangpo suture zones, Ladakh, India in the light of additional data. Himalayan Geol 2009, 30(1), 45-68.

Detailed biostratigraphic investigations were carried out in several sections of the lower Paleogene successions in the Zanskar Tethyan Zone (Ladakh), which lies at northern margin of the Indian Plate, and in the northerly Indus-Tsangpo Suture Zone (Ladakh) situated between the Indian and Asian plates. Based on additional palaeontological data, a revised and more precise zonal scheme, than was available earlier, has been proposed for these sediments. The revised biozones are correlated with the shallow benthic zones (SBZ) established earlier for the Tethyan realm by Serra-Kiel et al. (1998). A comprehensive chart showing correlation of lower Paleogene biozones, based mainly on larger foraminifera, in the Zanskar Tethyan and Indus-Tsangpo Suture zones and the Himalayan foothill belt, and the shallow benthic zones of the Tethyan realm is also presented.

5 illus, 4 table, 48 ref

020906   Khanna P P;Saini N K;Mujherjee P K;Purohit K K (NO, Wadia Institute of Himalayan Geology, Dehradun-248 001, Email: khannapp@wihg.res.in) : Appraisal of ICP-MS technique for determination of REEs: long term QC assessment of silicate rock analysis. Himalayan Geol 2009, 30(1), 95-99.

Silicate rocks, being geocbemically most complex material, pose great difficulties in accurate and precise measurement of ultra-trace abundance of elements like rare earths. The performance of a quadrupole type inductively coupled plasma mass spectrometer (ICP-MS) in this regard, was evaluated for determination of fourteen rare earth elements (REEs) in silicate rock samples. Complete analytical procedure adopted for routine determination of these elements using ICP-MS is described. All the determinations were carried out against well characterized reference rock materials. Possibility of determining REEs without using any internal standard was explored. It was noted that determinations without internal standard are well within the acceptable limits of errors provided the calibration standard is judiciously chosen. Single standard calibration is found valid for a wide range of concentrations because of the wide dynamic linear range of the technique.

4 table, 32 ref

020905   Karthikeyan A;Senthil Kumar G R (Earth Sciences Dep, Annamalai University, Annamalai Nagar-608 002, Email: gr_sentholkumar@rediffmail.com) : Groundwater quality assessment in part of Tindivanam taluk, Villupuram district, Tamil Nadu. Ultra Scient phys Sci 2010, 22(3), 519-32.

The study area, part of Tindivanam taluk in Villupuram district is located between 79°30' to 79°52' east longitude and 12° 18' to 12°24' north latitude. The study area consists of granite, granitic gneiss, and Charnockite of Archaean age which are with few intrusions by dolerite dyke and pegmatite. Ground water sample of 50 locations have been collected in two different seasons (pre and post monsoon). The collected samples have been analysed, and the analytical results brought into a digital output using a computer program HYCH. From the digital output, thematic maps such as Total Dissolved Solids, Total Hardness, Corrosivity Ratio, Groundwater Classification and Salinity and Sodium Hazard have been prepared using the GIS environment. It is inferred that the quality of gro':lndwater improves unevenly in different locations with respect to season indicating the recharge is not uniform. An appreciable amount of quality improvement has been observed along the northern and central portion of the study area. The quality improvement in north of the Veedur dam is poor. Groundwater collected from this location during post monsoon show a little reduction in TDS, TH, CR and USSL classification. It is suggested that by constructing large number of artificial recharge structures to trap monsoon rainwater along the northern and central part of the study area will improve the quality of groundwater remarkably. Designing of recharging wells along the southern region will result in considerable improvement both in the quality and quantity of groundwater.

6 illus, 4 tables, 9 ref

020904   Ghosh S K;Sinha S;Rohtash Kumar (NO, Wadia Institute of Himalayan Geology, Dehradun-248 001, Email: skghosh@wihg.res.in) : Response of 10 Ma thrusting event in the Himalayan foreland sediments, Kangra sub-basin, Himachal Pradesh, India. Himalayan Geol 2009, 30(1), 1-15.

Using detrital modes and sedimentation pattern of Late Neogene (11.3-5.5 Ma) coarsening up fluviatile succession of Himalayan foreland (Siwalik) of the Kangra sub-basin, an attempt has been made to understand the interrelationship of source area thrusting and their response in the detrital modes. The sedimentary succession consists of dark grey sandstone interbedded with purple mudstone in lower part, overlain by salt- and pepper grey sandstone and variegated mudstone and capped by thickly bedded conglomerate with minor amount of coarse - grained sandstone and mudstone. The sedimentologic parameters show change in palaeochannel pattern from meandering to braided streams at 10 Ma and inception of alluvial fan settings at around 5.5 Ma. A remarkable variation in detrital modes is also noticed between 10 and 9.0 Ma. The study suggests that prior to 10 Ma due to tectonic activity along the Chail Thrust (CT) the depocenter received high amount of Lesser- and Sub-Himalayan (LHZ and SHZ) footwall sedimentary and metasedimentary fragments. Subsequently, after 10 Ma, the detritus from the Chail Metamorphics Zone (CMZ) forming the hanging wall, became more abundant. The present study infers that the variation in the drainage pattern, sedimentation accumulation rate and detrital modes are collectively pertinent to the 10 Ma tectonic activity of the Chail Thrust.

8 illus, 3 table, 46 ref

020903   Dutta S;Pradhan R (Enviromental Studies Dep, Maharshi Dayaanand Saraswati Univ, Ajmer-305 009) : Analysis of ground water quality of areas adjacent to loco and carriage workshops, Ajmer, Rajasthan. Ecol Envir Conserv 2009, 15(2), 265-8.

Water is elixer of life. Water makes up more than two thirds of the weight of the human body. It is important to the mechanics of the human body. People can survive days, weeks or months without food, but only about four days without water.There has been a serious concern over the quality of water resources.The World Health Organization (WHO) estimates that 80% of all sickness in the world is attributable to unsafe water. Water may get impurities of various kinds from ground or soil with which it comes into contact it may also get contaminated with sewage and industrial wastes. The quality of water can be determined by detecting its physico-chemical properties. The present study involves ground water analysis of selected regions of Ajmer city. Samples were taken from hand pumps situated in 18 different localities adjacent to Loco & Carriage Workshops of the city, mainly used for drinking purpose. Loco & Carriage Workshops are the oldest workshops of Indian Railways. At present complete maintenance work for diesel locomotives, coaches and wagons is carried out in these workshops. About 9500 workers are employed in these workshops. The area around the workshops is also densely populated. Several physico-chemical parameters including pH, electrical conductivity, total dissolved solids, total hardness, salinity, chloride, sulphate, nitrate, sodium and fluoride were studied. The study indicates slight alkaline nature of ground water samples.TDS and total hardness values were observed higher than permissible limit. While sulphate and nitrate values were observed within the permissible limits as prescribed by WHO. The correlation coefficient showed significant relationship of pH with TDS, calcium hardness and sodium, potassium and fluoride concentration in ground water. EC shows significant effect on TDS. Statistical analysis also reveals significant effect of chloride content on alkalinity of ground water and that of Mg on hardness of water whereas chlorides shows a positive significant relationship with sulphate and sodium with potassium content in ground water. Except some selected sites, ground water is grossly suitable for domestic purposes.

3 tables, 6 ref

020902   Dutta M N;Das P K (Applied Geology Dep, Dibrugarh University, Dibrugarh-786 004, Email: kumar_das_pradip@yahoo.com.in) : Integrated approach from the study of foraminiferal fossil assemblages of the sylhet formation occurring in and around Lumshnong-Tongseng area of Jaintia hills, Meghalaya, India. Ultra Scient phys Sci 2010, 22(3), 499-518.

The Lumshnong area of laintia Hills of Meghalaya is stratigraphically most significant due to the occurrences of the Sylhet and Kopili Formations which are considered as the most complete Palaeocene-Eocene sequence. The Sylhet Formation consists of six alternating limestone and sandstone members. The three Limestone Members (viz. Lakadong Limestone, Umlatdoh Limestone and Prang Limestone) of the Sylhet Formation are rich in benthonic cainozoic foraminifera. The Palaeocene-Eocene age is assigned in Sylhet Formation from the study of the foraminiferal fossil assemblages. From the study, it is also found that the sediments were deposited under brakish to marine and subjected to several phases of transgressions and regressions of the sea. The limestone members were deposited under shallow marine with low-water energy condition. The foraminiferal fossil assemblages indicated as te characteristic found assemblase upper photic zone (depths less than 40 m) under warm and normal salinity of sea water.

2 illus, 1 table, 39 ref

020901   Choudhuri B K;Gururajan N S;Bikramaditya Singh R K (NO, Wadia Institute of Himalayan Geology, Dehradun-248 001, Email: bkchoudhuri@wihg.res.in) : Geology and structural evolution of the eastern Himalayan syntaxis. Himalayan Geol 2009, 30(1), 17-34.

This work deals with the geology and structural evolution of the eastern Himalayan syntaxial bend in eastern Arunachal Pradesh, which is a large scale antiform, known as the Siang Antiform. The crestal portion of the antiform exposed in the Namche Barwa peak area, is occupied by Higher Himalayan Crystallines. The area comprises of the following major litho-tectonic units and from south to north they are: the Sub-Himalayan sediments, Lesser Himalayan Sedimentary Sequence, Lesser Himalayan Crystallines, Higher Himalayan Crystallines (HHC), Trans-Himalayan tectonic units, namely the lower Tsangpo Suture Zone and the upper subduction related Lohit Plutonic Complex (LPC). Field investigations have been carried out along four major valleys viz, Siyom, Siang, Dibang and Lohit Valleys.The structural analysis indicates that the area has undergone four phases of deformation, out of which the first two phases are coaxial and the third phase of deformation has produced a regional scale NNW plunging Siang Antiform, which cross-folded the earlier structures. The variation in the pattern of foliation and lineation on both the limbs is interpreted as due to passive rotation during F3 folding and the western limb is more rotated than than the eastern limb.The last phase of deformation has affected the Trans-Himalayan units exposed in the eastern limb and reactivated the early thrusts, into dextral strike-slip faults. Both the Lesser and Higher Himalayan Crystallines exhibit inverted metamorphic character. The HHC exposed in the eastern limb of the Siang Antiform show an increase in both temperature and pressure towards higher structural levels and the inverted metamorphism is related to post metamorphic shearing. The high grade gneisses, exposed along the Walong Thrust that divide the LPC into western and eastern belts, forms the basement for the LPC and these crystalline rocks can be correlated with the Mogok Gneissic Belt of Central Burma in the south and the Nyainqentangiha Crystallines in the north that tectonically overlie the Tsangpo Suture Zone in eastern Tibet. Our field investigations in the syntaxial region suggest that the thrust bound litho-stratigraphic units have been translated towards south during the main phase of deformation (D2). Later, these tectonic units have been folded by the overall north trending Siang Antiform. The folding has tilted the early thrusts particularly in the eastern limb that were reactivated into dextral strike-slip faults. Subsequent indentation of the folded Indian plate rocks have folded the suture zone and the Gangdese belt and the northward migration have been accomodated by the strike-slip faults on both sides of the antiformal syntaxis.

8 illus, 2 table, 72 ref

020900   Ahmad B;Bhat M I;Bali B S (Geology & Geophysics Dep, Kashmir Univ, Srinagar, Email: bhatmi@hotmail.com) : Historical record of Earthquakes in the Kashmir Valley. Himalayan Geol 2009, 30(1), 75-84.

Researches aimed at enriching the record of earthquakes in a region have an important role in earthquake hazard assessment, especially for earthquake-prone regions like Kashmir Valley. This is usually done through the study of historical documents and/or paleoseismological studies; the latter allows access far beyond historical records. Kashmir has the distinction of having written history that goes back to almost 5,000 years, which makes it a very attractive bet for a search for historical earthquakes. However, the study of these historical records, particularly the Sanskrit records, like Nilamata Purana and Rajatarangi, which cover 70% of the recorded history of Kashmir, reveals a distressing absence of truly historical events, being mostly concerned with kings and cultural customs. In all we located mentioned of 17 earthquakes in the historical documents. Of these, only three earthquakes (in 2082-2041 BC, 844 AD and 1123 AD) find mention in the Sanskrit documents; the rest are mentioned mostly in the Persian records that begin from 16th century. Description of earthquakes, however, is sketchy. While some of the earthquakes may have their epicenters outside the Kashmir Valley, a few which caused severe damage to life and property and were associated with ground ruptures and long periods of aftershocks do appear to have been generated within the Valley. Srinagar and north Kashmir appear to have been repeatedly and severely affected by most of the earthquakes, possibly indicating role of three faults that the river Jehlum follows from its source in the south Kashmir to the Wular Lake via Baramulla and Uri gorge to Muzaffarabad.

1 illus, 1 table, 70 ref

020899   Ahire D U (Botany Dep, L.V.H. College, Panchavati, Nasik 422 003) : Survey of some medicinal plants of Dindori thesil in Nasik district (MS). Ecol Envir Conserv 2009, 15(2), 263-4.

The investigation gives an account different uses plants belonging to 25 medicinal plants to 25 genera and 21 families are dealts here with used by tribals and villagers for cure of different diseases.A history of medicinal plants is intimately connected with the history of botany. Since long medicine men vaidyas, tribal, priests used various plant parts in preparation of curde drugs.The aim of the present investigation is to enumerate the medicinal plants used by rural peoples and their medicinal uses.

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020898   Ahilan J;Senthil Kumar G R;Badrinarayanan T S (Earth Sciences Dep, Annamalai University, Annamalai Nagar-608 002, Email: gr_senthilkumar@rediffmail.com) : Qualitative approach for interpreting resistivity data to delineate weathered thickness and to explore the hard rock aquifer - a cae study form parts of Mangalore block, Cuddalore dist, Tamil Nadu. Ultra Scient phys Sci 2010, 22(3), 652-60.

In hard rock terrain, identification of groundwater potential is targeted in the weathered, fractured, fissured zones, etc. Electrical resistivity survey method is useful to delineate the weathered zone and its thickness. An attempt has been made to delineate the subsurface weathered zone and fracture pattern by using geoelectrical resistivity method. The chosen study area Lakkur sub basin falls in Mangalur block, Cuddalore district, Tamil Nadu. The basin consist charnockite and charnockitic gneiss rocks. Electrical resistivity profiling and vertical electrical soundings have been conducted at every 2 km interval in a grid pattern. Totally 36 YES were conducted and six profiles were carried out. The profile traverse is in N-S direction and the profile interval is 2 km. The resistivity data have been qualitatively and quantitatively analysed. A low resistivity anomaly at YES. 21 (Alambadi) has been observed in all the profiles and contour maps indicating a weaker and weathered zone. The qualitative approach is very essential before going in for quantitative approach.

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000253   Yadava M G;Ramesh R (Physical Research laboratory, , Navrangpura, Ahmedabad-380 009) : Past rainfall and trace element variations in a tropical speleothem from India. Mausam 2001, 52(1), 307-16.

An actively growing stalagmite (cave deposit) was collected in 1996 from the Dandak cave in Madhya Pradesh. Trace elements Mg, Sr and Ba were measured in order to asses their palaeoclimatic significance. More than 100% variations in the concentrations of trace elements have been observed during the growth period. The chemical and physical properties of the trace elements along with the data of stable isotope ratios of oxygen and carbon from earlier work has been discussed. Ratio of Ba to Sr concentrations has remained constant suggesting that the soil layers and bedrock dissolution have contributed the same proporation of trace elements to the cave seepage water. Slowly varying components in the Mg, Sr and Ba concentrations and δ¹³C profiles show high degress of correlations. It is found that changes in the trace elements are mainly driven by the varying intensity of past rainfally. Trace element variations of speleothems in tropical regions can be used as indicators of the past rainfall intensities. Different climatic intervals are characterised based on trace elements and stable isotopes. Period 3700 to 3350 yr BP was found to be arid. High rainfall was observed between 3350 to 3200 yr BP. After a hiatus period of 2000 yr due to non-climate dependent processes, again a high rainfall phase between 1200 to 400 yr BP was observed with a peak level at <126> 650 yr BP....

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000252   Unnikrishnan A S;Gouveia A D;Vethamony P (NO, Natl Inst Oceanog, Panaji, Goa-403 004) : Tidal regime in gulf of Kutch, West Coast of India, by 2D model. J Waterway Port Cstl ocean Engng 2001, 127(6), 355-6.

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000251   Sunmonu L A;Dimri V P;Ravi Prakash M;Bansal A R (Fractals in Geophysics Group, National Geophysical Research Institute, Hyderabad-500 007) : Multifractal approach to the time series of M≥7.0 earthquake in Himalayan region and its vicinity during 1985-1995. J Geol Soc India 2001, 58(2), 163-9.

Presented time series analysis of multifractal properties of M≥7.0 earthquakes in Himalaya and vicinity during the period 1895-1995. The multifractal analysis of complex phenomena involves the estimation and interpretation of D_q - q relation. Investigations show that: the distribution of earthquakes of M≥7.0 on the time axis has a multifractal set, well distributed, steep type decreasing function of D_q with increasing q, indicated high rates of accumulation and release; therefore, leading to adjustment of a large scale stress field in the area, and value of D₂ + 0.95 <62> D₃ <62> D ∞ = 0.80.

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000250   Sukumaran P V;Nambiar A R (Geological Survey of India, Geodata Division, , Nagpur-440 006) : Occurrence of chromiferous lodestone near Chalingal, Kasaragod District, Kerala. J Geol Soc India 2001, 58(2), 171-3.

Communication reports the new find of chromiferous lodestone near Chalingal village in Kasaragod District of Kerala. The chemistry and mineralogy of the lodestone suggest that the band may have segregated during the early phase of magmatic differentiation.

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000249   Subbaraya B H;Shyam Lal;Naja M (NO, , ISRO Headquarters, Bangalore-560 094) : Tropical tropospheric chemistry and climate change. Mausam 2001, 52(1), 97-108.

Systematic programme of monitoring surface ozone and its precursor gases CH₄, CO and NO_x (NO + NO₂) at some selected sites in the Indian region was started under ISRO's geosphere biosphere programme in 1991. Measurements have been made at Ahmedabad an urban polluted site, Gadanki a rural relatively clean site, Gurusikhar a high altitude site representative of the free troposphere and Trivandrum a coastal (relatively clean) site influenced by marine air. The data has been used to study different features of troposphere chemistry in the tropics. Some of the results from this programme relevant to the climate change problem are presented.

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000248   Stephenson D B;Douville H;Rupa Kumar K (Department of Meteorology, University of Reading, Earley Gate, P.O. Box 243, Reading RG6 6BB,UK) : Searching for a fingerprint of global warming in the Asian summer monsoon. Mausam 2001, 52(1), 213-20.

Investigates possible trends in several largescale indices that describe the Asian summer monsoon. Results from recent atmospheric general circulation experiments are used to provide clues as to how the monsoon might be changing due to the effects of global warming. Interestingly, this study has found that the largescale wind shear monsoon indices have been decreasing at a rate of 0.1-0.3% per year (based on NCEP/NCAR reanalyses 1958-98) in quantitative agreement with recent results from doubled CO₂ simulations made using several state-of-the-art climate models. Nevertheless, despite the weakening of the monsoon circulation, all-India rainfall shows no clear trend in either the model results or in the observation reanalyses from 1958-98. Multiple regression is used to separate out the "dynamical" contribution from the observed all-India rainfall index, and a clear increasing trend then emerges in the "non-dynamical" residual. A simple dimensionless Multivariate Monsoon index (MMI) is proposed that could be of use in monitoring global warming changes in the monsoon.

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000247   Srivastava P;Chandran P;Ray S K;Bhattacharyya T (Division of Soil Resource Studies, National Bureau of Soil Survey and Land Use Planning, Nagpur-440 010) : Evidence of chemical degradation in tropical ferruginous soils of Southern India. Clay Res 2001, 20(1), 31-41.

Describes ferruginous soils of Jamakhandi series in southern India which are mildly alkaline, calcareous and high in base saturation. These soils have very thick argilic horizon immediately after a thin Ap horizon indicating that these are relict paleosols formed in an earlier humid climate. The silt and clay fractions of these soils indicate the presence of smectite, kaolin and mica minerals. The fine clay fractions of these soils are dominated by smectite of both low and high charge density. Presence of pedogenic carbonate as spongy nodules and cluster of lubinite needles below 40 cm depth indicates their formation in the prevailing semi-arid climate. Supersaturation of the soil solution with calcium carbonate facilitating the formation of lubinite crystals in the lower horizons was favoured by the presence of smectite clay. The formation of pedogenic CaCO3 caused the development of subsoil sodicity in the lower horizons. The rate of CaCO3 formation and the sodicity development may not be very alarming. However, it is apprehended that in continuation of the natural degradation process, drainage of the soils will be gradually impaired.

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000246   Sontakke N A;Shea D;Madden R A;Katz R W (NO, Indian Institute of Tropical Meteorology, Pashan, Pune-411 008) : Potential for long-range regional precipitation prediction over India. Mausam 2001, 52(1), 47-56.

Potential for long-range precipitation prediction over the Indian monsoon region is generally good where climate noise (i.e. variability due to daily weather fluctuations) is small as compared to the climate signal (i.e. variability due to year to year fluctuations in monthly/seasonal means) being in the tropical belt. In order to understand the potential on smaller spatial scales, the ratios of interannual variability to that associated with climate noise have been computed for precipitation of four seasons as well as SW monsoon sub-seasons/months over 1656 stations in the Indian subcontinent. Precipitation in SW monsoon has been found potentially predictable on seasonal as well as intraseasonal scale. The west coast and contiguous northwest India, part of the `northeast India are more predictable. Potential for long-range prediction over northwest India is highest during the active monsoon period from July to September. Over eastern penisnula potential for prediction is generally found low whereas over northcentral India it is always moderate. Over northern latitudes precipitation due to western disturbances during January to May is potentially predictable. Precipitation over southeast India and Sri Lanka during October to February due to northeast (NE) monsoon shows good potential for long-range prediction.

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000245   Sinha-Roy S (NO, Birla Institute of Scientific Research, Statue Circle, Jaipur-302 001) : New approach to the analysis of transverse river valley profiles and implications for morphotectonics - a case study in Rajasthan. Curr Sci 2001, 81(1), 106-12.

Study of river profiles provides significant information on both hydrodynamic factors and geomorphic features of drainage basins. Longitudinal river profiles have been extensively studied and different parameters have been proposed by various authors for these profiles, but transverse river valley profiles (TRPs) have not received similar attention. A new approach to the TRP analysis has been proposed here. It identifies several TRP parameters that are useful for inter-TRP and as well as inter-drainage basin comparisons. These are also useful to derive drainage basin attributes such as valley symmetry and the state of valley erosion, identify and correlate geomorphic features such as plantation surfaces, and importantly, to draw morphotectonic inferences. The procedure has been successfully tested in a case study of the Banas drainage basin, Rajasthan.

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000244   Sinha Roy S (NO, Birla Institute of Scientific Research, Statue Circle, Jaipur-302 001) : Neotectonic significance of longitudinal river profiles - an example from the Banas Drainage Basin, Rajasthan. J Geol Soc India 2001, 58(2), 143-56.

Longitudinal river profiles can be quantified by normalizing the elevation and the distance along rivers. Several parameters such as profile shape (concavity), gradient fluctuations (knickpoints), river grade and valley incision have been derived from longitudinal rive profile. These quantified parameters and their interrelations are useful in comparing different drainage basins. Ten tributaries (5th, 4th and 3rd order) whose cumulative catchment area is ca. 82% of the 6th order Banas drainage basin, the largest in Rajasthan, have been studied. Their longitudinal profile parameters have been interpreted, especially in respect of neotectonic activities. It is concluded that the Aravalli hill range and the surrounding areas in the SW segment of the basin are being currrently uplifted, while the NE block is generally subsiding. Within these major neotectonic blocks, there are several sub-blocks that have differentially moved nearly vertically to give rise to horst-graben structures bounded by active faults, generally trending N-S and NE-SW. Some of these faults represent reactivated old dislocation zones. These conclusions have been substantiated by neotectonically controlled geomorphic features. Strike-slip faulting in the NE neotectonic block and differential vertical movement of the neotectonic sub-blocks have played an important role in forming the structural depressions and grabens.

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000243   Singh R P;Bhoi S;Sahoo A K;Uday Raj; Ravindranath S (Department of Civil Engineering, Indian Institute of Technology, Kanpur-208 016) : Surface manifestations after the Gujarat earthquake. Curr Sci 2001, 81(2), 164-6.

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000242   Singh R D;Mishra S K;Chowdhary H (NO, Nat Inst Hydro, Roorkee-247 667) : Regional flow-duration models for large number of ungauged Himalayan catchments for planning microhydro projects. J Hydrol Engng 2001, 6(4), 310-16.

In the Himalayan region of India, most prospective sites for microhydro, projects are ungauged and there are insignificant data for analysis. Design flow estimates are made using a regional flow-duration curve. Regional studies on Himalayan watersheds do not appear to have been reported in the literature. Therefore, models are developed for 1,200 ungauged watersheds of the Lower Himalayas. To this end, the region, comparatively larger in size than the catchment, is assumed to be hydrometeorologically homogeneous in its behavior. Formulation of models is based on data transfer between gauged watersheds of the same region, statistical normalization and empirical regional relation. The performance of a specific model developed for Himachal Pradesh (Region C) is evaluated using the data of 13 watersheds in calibration and 4 watersheds in validation. It is found that the statistical approach of quantile estimation (nondimensional) performs satisfactorily in calibration as well as in validation. The simple power relation for mean flow-estimation, as well as the complete model, performs well in calibration and less satisfactorily in validation because of the short length of data.

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000241   Singh N;Patwardhan S K (NO, Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, Pashan, Pune-411 008) : Prediction of terrestrial and etraterrestrial parameters/by modelling and extrapolating their natural regularities. Mausam 2001, 52(1), 117-32.

Twenty-four time series of terrestrial and extraterrestrial parameters, which visibly show strong regularity, are considered in the study. They can be broadly grouped into five categories: inter-annual series of number of storms/depressions over the Indian region, seasonal and annual mean northern hemisphere land-area surface air temperature and the annual mean sunspot number (chosen cases of long term/short term trends or oscillation); monthly sequence of zonal wind at 50- hPa, 30-hPa and 10- hPa levels over Balboa (representative of quasi-biennial oscillation); monthly sequence of surface air temperature (SAT) over the Indian region (strongly dominated by seasonality) monthly sequence of sea surface temperature (SST) of tropical Indian and Pacific Oceans (aperiodic oscillations related to El Nino/La Nina) and sequence of monthly sea level pressure (SLP) of selected places over ENSO region (seasonality and oscillation). Best predictions are obtained for the SLP followed by SAT and SST due to strong domination of seasonality and/or aperiodic oscillations. The predictions are found satisfactory for the lower stratospheric zonal wind over Balboa, which displays quasi-periodic oscillations. Because of a steep declining trend a reliable prediction of number of storms/depressions over India is possible by the method. Prediction of northern hemisphere surface air temperature anomaly is not found satisfactory.

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000240   Singh C B;Ghosh L K (Math Modelling Ctr, Cent Water and Power Res Stn, Pune-24) : Tidal regime in Gulf of Kutch, West Coast of India, by 2D model. J Waterway Port Cstl ocean Engng 2001, 127(6), 353-5.

000239   Shukla R R (NO, Banaras Hindu University, Varanasi-221 005) : Petrographic characterization and evolution of the coal from Pench-Kanhan valley and Pathakhera coalfields, Satpura basin. J Geol Soc India 2001, 58(1), 79.

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000238   Shekhawat L S;Joshi D W;Pandit M K (Geological Survey of India, , Jhalana Dungari, Jaipur-302 004) : Relook into the status of granitoids and conglomerate in Salumber-Jaisamand area, southern Rajasthan - implications for the stratigraphy of the palaeoproterozoic Aravalli fold belt. J Geol Soc India 2001, 58(1), 53-63.

Detailed geological mapping (1:25,000) of the Jaisamand-Salumber area in south Rajasthan has brought out modifications and additions to the existing published maps. Significant modifications in the outcrop pattern relate to the disposition of (a) polymictic conglomerate, feldspathic quartzite and calcareous quartzite-dolomite unit in the Ora-Jaisamand area, (b) granitoid bodies, and (c) polymictic conglomerate occurring southwest of Salumber. A better understanding of the inter relationship of significant litho units has necessitated a relook into-the Aravalli stratigraphy of the area, particularly with respect to the granitoids and conglomerate. Geological mapping has also helped in identifying some stratigraphically important litho-units, such as polymictic conglomerate from northwest of Paluna, calcareous grit/calcareous quartzite-dolomite from west of Piladhar, and calcareous quartzite-dolomite along the northeastern limb of Ora - Jaisamand anticline. The Aravalli sequence exposed in the area can be divided into Salumber Group (lower Aravalli) and Jaisamand Group (upper Aravalli), separated by an unconformity. The two groups also differ in lithologic assemblages. The granitoids are intrusive into the volcano-sedimentary sequence of the Salumber Group and form the basement for the Jaisamand Group.

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000237   Seshunarayana T;Prabhakara Prasad P;Prasada Rao S V V;Subrahmanyam K;Varadarajan G (NO, National Geophysical Research Institute, Hyderabad) : Crosshole velocity measurement to assess the nature of rockmass on which to erect a heavy Buddha statue in Hyderabad. J Geol Soc India 2001, 58(1), 65-8.

Crosshole seismic survey was conducted to decipher the nature of the exposed rock mass in Hussain Sagar Lake at Hyderabad to erect a monolithic Buddha statue weighing about 470 tonnes. The purpose of the survey was to determine the continuity of subsurface conditions between borehole locations. The technique consists of in situ measurements of travel time of the seismic waves generated by an impulse in one borehole, its reception in the other and computation of seismic velocity. Analysis of the velocity data provided necessary information regarding the soundness of the rock mass.

000236   Senthiul Kumar P;Parthasarathy G;Das Sharma S;Srinivasan R;Krishnamurthy P (NO, National Geophysical Research Institute, Uppal Road, Hyderabad-500 007) : Mineralogical and geochemical study on carbonate veins of the Salem-Attur fault zone, southern India: evidence for carbonatitic affinity. J Geol Soc India 2001, 58(1), 15-26.

Carbonate veins up to few metres thick have been recognised in the E-W striking Salem-Attur deep fault zone which represents the eastern extention of the Moyar fault in the southern granulite terrane of India. X-ray diffraction, FTIR spectroscopy and chemical analyses show calcite, ankerite, siderite and benstonite as dominant minerals besides minor apatite and green biotite. Whole rock compositions show enrichment of light REE, Ba, Sr and Nb. C and O isotopic data determined for calcite (δ¹³C = -4.9 to -5.1% V-PDB and δ¹⁸O = 9 to 9.2% V-SMOW) points to a mantle origin. The chemical characteristics therefore suggest that the carbonate veins have carbonatitic affinity. The FTIR spectra provide evidence for presence of H₂O and CH₄ in addition to CO₂ in the carbonate minerals of these veins.

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000235   Sarkar B C (Department of Applied Geology Indian School of Mines, , Dhanbad-826 004) : Statistical approach to evolving guides for mica search in Nellore mica belt around Gudur, Andhra Pradesh. J Geol Soc India 2001, 58(1), 27-35.

Search for mica deposits presents peculiar problems owing to great complexities associated with pegmatite bodies. All pegmatites do not develop mica and not all mica-bearing pegmatites carry commercially workable quantity of mica. Prospecting for mica has therefore been a highly speculative and risky venture. It is in this context that the use of characteristic analysis, a multivariate statistical technique, has been made for the development of a composite geological model of the most typical indices of pegmatites of Nellore mica belt around Gudur in Andhra Pradesh, in order to evolve prospecting guides for mica search. Data pertaining to geological variables gathered through surface mapping, field observation and geological studies of pegmatite bodies of Gudur mica region have been statistically treated for characteristic analysis. The approach elucidates most typical characteristics of pegmatites favourable for hosting commercially workable mica deposits. The geological variables associated with mica mineralization have been selected through an extensive survey and analogy. The model is governed by choosing sample locations and geological variables that best reflect mica mineralization. Presence of albite, undeformed pegmatite and kaolinization have been determined to be the most characteristic indices for mica search in the pegmatites of Nellore mica belt around Gudur.

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000234   Sangode S J;Suresh N;Bagati T N (Sedimentology Group, Wadia Institute of Himalayan Geology, 33 General Mahadeo Singh Road, Dehra Dun-248 001) : Godavari source in the Bengal fan sediments - results from magnetic susceptibility dispersal pattern. Curr Sci 2001, 80(5), 660-4.

The Bay of Bengal has been receiving erosional products dominantly from the Himalaya since Mid-Eocene time through the Ganges-Brahmaputra river system, with minor contribution from peninsular rivers. Spatial distribution of magnetic susceptibility in 13 cores from the western part of the Bengal sub-marine fan indicates predominance of Godavari river source (peninsular India) during the Late Quaternary. Sequential down-core analysis of magnetic susceptibilty-dispersal patterns suggests that the Godavari source dominated the top 100 cm of the Bengal fan sedimentation. This changeover is attributed to weakening of the Himalayan source (Ganges-Brahmaputra) after the Last Glacial Maxima (23-14 Ka BP).

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000233   Sangode S J;Rohtash Kumar;Ghosh S K (NO, Wadia Institute of Himalayan Geology, Dehra Dun-248 001) : Application of magnetic fabric studies in an ancient fluvial sequence of NW Himalaya. Curr Sci 2001, 81(1), 66-71.

Reports an account of sedimentary magnetic fabrics in 44 channel sand-bodies of a Siwalik fluvial sequence (6 to 0.5 Ma) near Nahan, Himachal Pradesh. These sandstones in distal alluvial fan-setting record oblate fabrics (Tmean=0.51) and relatively higher degree of anisotropy (Pjmean = 1.05). The minimum axis (K3) of the anisotropy ellipsoid is aligned parallel to the palaeoflow direction by traction carpet mechanism. Variations with time of latitudes derived from azimuth of principle ellipsoid axes show a greater sensitivity to the basin tectonic impulses with smaller response time than conventional methods. This signifies the scope of magnetic fabric techniques for palaeo-hydrodynamic and basin tectonic studies in the Indo-Gangetic foreland of Himalaya.

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000232   Rupa Kumar K;Ashrit R G (NO, Indian Institute of Tropical Meteorology, Dr. Homi Bhaba Road, Pune-411 008) : Regional aspects of global climate change simulations - validation and assessment of climate response over Indian monsoon region to transient increase of greenhouse gases and sulfate aerosols. Mausam 2001, 52(1), 229-44.

Examines two AOGCM (ECHAM4/OPYC3 and HadCM2) climate change simulations for their performance in the simulation of monsoon climate over India and the sensitivity of the simulated monsoon climate to transient changes in the atmospheric concentrations of greenhouse gases and sulfate aerosols. The results show that the two models simulate the gross features of climate over India reasonably well. However the inter-model differences in simulation of mean characteristics, sensitivity to forcing and in the simulation of climate change suggest need for caution. Further an empirical downscaling approach is used to assess the possibility of using GCM projectixons for preparation of regional climate change scenario for India.

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000231   Reddy P R;Satyavani N (National Geophysical Research Institute, , Uppal Road, Hyderabad-500 007) : Divergent structure and composition of the two colliding protocontinents as evidenced from seismic studies. Curr Sci 2001, 80(5), 685-7.

Coincident reflection/refraction studies across Central Indian Suture (CIS) have yielded crustal structure. The refraction input was confined to a part of the profile, resulting in non-availability of velocity-depth information, an essential component for understanding the composition and rheology of different crustal columns. Using a well-known algorithm of Megallaa, deep reflection data have been utilized in arriving at crustal interval velocity information for the region between Katangi and Kalimati across CIS. It is evident from the results that the two crustal segments on either side of CIS that were imaged earlier by deep reflection profiling (TWT cross-sections), have significantly different compositions (From velocity information). It is noticed that the north-western crustal segment, belonging to Bundelkhand protocontinent has denser lower crust with a velocity of about 7.0 km/s and relatively normal Pn velocity of 8.1 km/s (for the uppermost mantle velocity). The south-eastern crustal segment belonging to the Deccan protocontinent, while having a similar velocity structure for upper and mid crustal columns (thereby probably similar composition) has a relatively less denser lower crust (with a velocity of 6.7 km/s). It is also interesting to note that the Pn velocity in this segment is only of the order of 7.8-7.9 km/s. Tectonic significance of the results is discussed.

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