Open Access Quarterly e-Journal devoted to the development of Earth Sciences

Earth Science India

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Volume V (I), January, 2012

 Contents

esi.2012.1.04

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Neogene Pectinid Bivalves from Kolasib of Mizoram, Northeastern India

Baharul Islam Mazumder and Raghavendra Prasad Tiwari


Abstract:

   

Neogene bivalve fauna from the Middle and Upper Bhuban units of Bhuban
Formation of the Surma Group have been collected from stone quarries of Kolasib area of Mizoram (Northeastern India). These quarries are located along the sides of Silchar-Kolasib road section. Seven bivalve taxa of the family Pectinidae are identified. Pecten (Pecten) kachharai is recorded as the new species; Chlamys (Argopecten) senatoria (Gmelin) var. kolasibensis as a new variety and Cyclopecten (Chlamydella) sp., Parvamusium sp. and Pecten
sp. are kept in open nomenclature because of poor preservation. Most of the taxa are represented by a single valve or a few disarticulated valves. These pectinids form only a small part of the fossil groups present in the Bhuban Formation of Kolasib area. Though bivalves constitute main component of the fossil fauna, gastropods, echinoids, decapods, fish teeth, barnacles and
scaphopods are also present in the study area.

 
esi.2012.1.03

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Bolivina batanensis sp. nov, a new benthonic foraminifera from Niger Delta, Nigeria

Enam O. Obiosio


Abstract:

   

A new species of benthonic foraminifera Bolivina batanensis sp.nov belonging to the genus Bolivina has been found in the western Niger Delta basin sediments. This species is restricted to Early Miocene and could serve as an index fossil.

 
esi.2012.1.02

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Study of Magnetospheric Electron Density Inferred from Whistler Observations

Sandhya Mishra and A. K. Singh


Abstract:

   

The observation of equatorial electron density ne0, inferred from the analysis of whistlers recorded at some ground-based stations to explain the typical dependence of electron density along the magnetospheric field lines are carried out. Using a data set observed at few stations, we have compared the ne values with respect to the maximum field line radius LRE, to present an overview of the field line variation of electron density at lower/mid latitudes. The average equatorial profiles of ne0 vs. Rmax along with trend of the parallel scale length for field line variation of density given as [L (LRE)/ ] across the entire length 1.07  L  4.56 have been illustrated. Also clear independence of the power law index , from the latitudinal value is discussed in the present paper. Thus, it is demonstrated that the whistler waves recorded at a number of ground based stations spread over latitudes and longitudes are helpful in studying the field line distribution of electron density in the magnetosphere.

 
esi.2012.1.01

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Engineering Geological Investigations of Rock Mass from the Excavated North Wall Face in the Pump House Area of Mahatma Gandhi Lift Irrigation Scheme-III, District Mahboobnagar, Andhra Pradesh, India

A. K. Naithani, Manoj Kumar, Rabi Bhusan and P.C. Nawani


Abstract:

   

Vertical wall and foundation floor geological mapping of the important structures is essential to provide data input for geological interpretations during construction and also it forms valuable documentation for post-construction stage. For important structures like deep surge pool and pump house of lift irrigation, the supporting wall and foundation strata have to be well studied and documented for credible geologic interpretations. MGLIS-III is being constructed for the irrigation of drought prone upland areas of Mahboobnagar District, Andhra Pradesh. In order to evaluate the basic design parameters for pump house of Mahatma Gandhi Lift Irrigation cheme-III, engineering geological mapping on 1:200 scale of north wall was carried out. All the lithological variance and the structural discontinuities in rock mass of the wall were identified and mapped. Classification of rock mass using Tunnelling Quality Index ‘Q’ of Barton et al. (1974, 1980) has been done. Based on investigations geotechnical problems were identified and remedial measures were suggested for the vertical wall.

 
 

  

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