Brunton Compass Research Articles

Engineering geological and geotechnical evaluation of Sathya Sai Prasanthi Nilayam railway tunnel, Andhra Pradesh, India

Detailed engineering geological investigations were carried out for a railway tunnel which was constructed more than two decades ago. 3D engineering geological mapping was carried out using Brunton Compass and Total Station Surveying instruments in 1:100 scale. Coarse-grained pink and grey granite, hornblende-biotite gneiss and dolerite dyke of Archaean age and Lower Proterozoic age were mapped. Rock mass was intersected by sub-horizontal, inclined, and vertical joint sets, which were continuous and persistent, smooth, and planar with thick filling of decomposed and crushed sheared material or with thin coating of clay material. Based on the Q-system, rock mass was classified into different classes. On the basis of large-scale engineering geological mapping and Norwegian Method of Tunnelling, a support system was recommended which includes rock bolt, fibre reinforced shotcrete, grouting and reinforced ribs of sprayed concrete and the same is implemented by the agency. As per the best knowledge of the authors, reinforced ribs of sprayed concrete are first time used for transportation tunnels in India and it will be more effective if it will be compared with ISMB or Lattice Girder.

Investigation and mapping of geological construction materials in parts of chemoga river sub basin, debre markos, Ethiopia

Currently the demands of geomaterials are intensively increasing all over the country regarding to the expansions of towns for the consumption of engineering structures and buildings. Therefore, searching workable, serviceable and accessible geomaterials nearby areas is a vital subject to stabilize the inflation of geomaterials. The present research was carried out in the Chemoga river sub basin in the Southern direction of Debre Markos town, North Western Ethiopia. To meet out the objectives, detailed surface explorations were carried out through systematically selected travel lines (across the strike and along streams) to detect the different lithologic formations and the contacts; A number of representative rock samples were collected for visual interpretations; GPS reading and metallic meter were the materials used in the field to quantify stratigraphic units, bedding thickness and lamination the lithologic formations; The Brunton compass was used in the field to measure the orientation (dip direction, dip amount and strikes) of geological structures. Besides to this, related literatures were reviewed to have a general background on the subject matter.Basalt and Sandstone are the dominant lithogical units in the study area and have existed with about an average thickness of 500 m and 145 m respectively. Fresh to slightly weathered basalt and columnar basalt that used as a masonry stones are ease to access, workable and the most dominant lithologic units in the study area. Fine to coarse grain reddish to light color sandstone interbedded with siltstone and mudstone is well exposed. Based on the detail field exploration and judgments, Sandstone unit has been well exposed in a desirable potential and quality. And based on the detail field investigation and researcher judgment, the sandstone resource could answer the demands of construction materials for the surrounding areas of Debre Markos town for several thousand of years. Geometrically, mostly massive and steep rock faces are well developed which are difficult for quarrying process and required high explosive materials. Generally, a sandstone rock unit is surrounded by three major normal faults and inaccessible as compared to basalt unit. Regarding to environmental influences/effects, the area is sparsely farmed and it is not common that an extractive activity does not show any environmental and social impacts. Chert is exposed on geographically limited area and rarely observed following stream cuts. Chert and basalt units are slightly to highly weathered and showed alterations on the surface. Finally, the potential and the spatial distribution of geomaterials are investigated and revealed on the map using ArcGIS software and on the basis of the findings of the present research, recommendations are forwarded.

The Relationship between Lineament Patterns and Mass Movements in the Municipality of Vitória (Espírito Santo, Southeast Brazil)

The main objective of this research is to analyze and relate lineament patterns to the occurrence of mass movements in the municipality of Vitória (Espírito Santo, Brazil). The methodology used consists of cabinet and field analyses. In a cabinet, Lineament Maps were made from the manual extraction technique, using ArcGIS 10.5 tools, on a Digital Elevation Model (DEM) with different artificial lighting (scale 1:110000) and Digital Orthophotos (scale 1:25000) and orientation rosettes generated. In the field, the geological structures were identified and analyzed from the lineaments identified in the cabinet, and their orientations were measured (Brunton compass). These data were integrated and analyzed from the Municipal Civil Defense mass movements records, referring to the period between 2006 and 2020. It was possible to verify the orientation patterns of dominant geological structures in the area (NNW-SSE and NW-SE, followed by NE-SW), including all measured fractures. At the regional scale, more mass movements occurred near NNW-SSE, NW-SE, and NE-SW orientation lineaments. At the local scale, these processes occurred more frequently in the vicinity of NNW-SSE, NNE-SSW, and NE-SW orientation lineaments. Data analysis demonstrates the important relationship between lineaments and occurrences of mass movements with regional geological structures and neotectonic events of the Espírito Santo in altered rocks of the Precambrian basement and Cenozoic deposits. The data revealed an association between the density of geological structures and the occurrence of mass movements since the increase in density is directly proportional to these processes, except for the Very High -density class, which presented little area representation.

Faydhat Nayif Archaeological Site, AsSubbiyah, Kuwait: A Discovery of an Ancient Blacksmith Village along the North Shore of the Kuwait Bay, Kuwait

This paper is a report on a discovery of an ancient human settlement next to the Faydhat Nayif pond in the AsSubbiyah area, north of Kuwait Bay, Kuwait. It also presents a description of the site and its artefacts. The settlement, named by the author Faydhat Nayif Archaeological Site, is composed of two parts, the main cluster of gallery remains and a small satellite, the Sonna Village. The main site contains foundations of around fifty galleries. The state of preservation of the foundations varies from excellent to weak. The dominant architectural plan for the galleries is a rectangle. Infrastructural components associated with the foundations are iron smelters and iron tools. Artefacts include fabricated iron tools, fishhooks and fishnets, pottery fragments, glass shards, and animal bones. The craft of the inhabitants revolves around iron smelting and tool fabrication, and hence, the “blacksmith” status. The research method followed in the research is simple classical surveying techniques utilizing a Brunton compass and a measuring tape. Imaging of the galleries used digital cameras. The settlement displays three styles of construction. The first style is that of a faint triangle, seen mostly in the southern and western sides of the site. The second style shows as a rectangle, with most galleries containing two rooms and external bathrooms. The third style of construction is similar to the second style, except for the presence of wood vestiges and the gypsum lining of the gallery walls. These differences between the three styles suggest three episodes of occupancy. One of the occupancies was by the AsSubbah tribe. The site served repeatedly as a center of population and pilgrim rest area, as well as cultural exchanges in the last 1500 years.

Application of Photogrammetric Technique in Determination of Rock Slope Stability of Quarry

Identify the characterization and orientation of the discontinuities such as joint, bedding and fault is a requirement in rock slope stability analysis because discontinuities control the type of failure. Until today, geologist still practices the classical method to determine the dip and strike of discontinuities which is by using Brunton compass at the field. It is difficult to measure at the inaccessible area, dangerous when having physical contact with the steep, fractured slope and time consuming to cover a large area are limitations of this method. A recent development in remote sensing has introduced Terrestrial Laser Scanner (TLS) as an indirect method in mapping the rock slopes by using the point cloud data. TLS allows for extremely rapid acquisition of large amounts of 3D coordinates of objects’ surfaces, with high precision measurement. The aim of this paper is to apply Terrestrial Laser Scanner (TLS) in determine the dip and strikes of the joints and compare the value with the hand measurement at a granite quarry in Ulu Choh, Johor. Analysis of the data shows the TLS method able to obtain the data for the joints and show almost the same trend. Thus, TLS is an efficient technology in geological practice.

Late Miocene to late Pleistocene geomagnetic secular variation at high northern latitudes

SUMMARYWe report a palaeomagnetic study of Icelandic lavas of late Miocene to late Pliocene age to test the geocentric axial dipole hypothesis at high northern latitudes. Cores were sampled from 125 sites in the Fljótsdalur valley in eastern Iceland, and hand samples were taken for 17 new incremental heating 40Ar/39Ar age determinations. 96 per cent of the cores were oriented using both a Brunton compass and a sun compass. Comparison of the magnetic and sun azimuths reveals deviations of ±5°, ±10° and ±20°, respectively, for 42, 16 and 3 per cent of the data points, indicating that core sampling intended for palaeosecular variation (PSV) studies at high northern latitudes should be oriented by sun. A total of 1279 independent specimens were subjected to AF- and thermal-demagnetization for palaeodirectional analysis, and well-grouped site mean directions were obtained for 123 sites of which 113 were found to be independent sites. Applying a selection criteria of k > 50 and N ≥ 5 (Nmean = 9.5), we obtain a combined grand mean direction for 46 normal and 53 reverse (for VGPlat > ±45°) polarity sites of declination = 5.6° and inclination = 77.5° that is not significantly different from that expected from a GAD field. The corresponding palaeomagnetic pole position (VGPlat = 86.3°N, VGPlon = 21.2°E, dp/dm = 4.0°/4.3°) is coincident with the North Pole within the 95 per cent confidence limits. An updated age model is constructed based on the 40Ar/39Ar ages, showing that the majority of the Fljótsdalur lavas fall within 2–7 Ma. We combine the Fljótsdalur data with existing data from the nearby Jökuldalur valley. The 154 palaeodirections are well-dispersed between 1 and 7 Ma and constitute a high-quality data set for PSV analysis. Our results partly support previous conclusions of a generally higher dispersion during reverse polarity intervals. However, when comparing our Matutayma data with Brunhes age data from Jan Mayen, we find no evidence of a higher VGP scatter during the Matuyama as previously suggested. When comparing our VGP scatter to the two commonly used models for VGP dispersion: Model G and TK03, we find a good fit for all 1–7 Ma VGP scatter data SB(1–7) to Model G, whereas SB(1–7) is not fitted by TK03, even when considering the uncertainty of SB(1–7). We also find that all VGP scatter estimates, except that for the Gilbert subset, are consistent with Model G, while the discrepancy with TK03 is generally larger.

Paleomagnetic Results from Archaeological Sites in Argentinean Patagonia: Evidence for the Holocene Geomagnetic Excursions in Southern South America and Its Chronostratigraphic Implications

Detailed palaeomagnetic research performed in archaeological and paleontological sites in southern South America yielded a number of highly fluctuating paleosecular variation records with geomagnetic field excursion(s) during the Holocene. To assess this topic a variety of sections of recent sediments were sampled. In the case presented here they belong from diverse continental sedimentary sequences formed in coastal marine and cave’s environments. Paleomagnetic samplings were performed in several deposits in San Blas Bay and Pali Aike areas, respectively located in the northern and southern parts of Argentinean Patagonia region. To collect samples, cylindrical plastic containers 2.5 cm long and 2 cm diameter were carefully pushed into the sections, overlying each other by about 50 percent. Their strike and dip were measured using a Brunton compass and inclinometer; they were consolidated with sodium silicate after removal and numbered from top to bottom. All samples were subjected to progressive AF demagnetization in steps of 3, 6, 9, 12, 15, 20, 25, 30, 40 and 60 mT in a 3-axis static degausser attached to a 2 G cryogenic magnetometer. Additional steps from 80 to 120 mT were used in some samples. Characteristic remnant magnetization was calculated using principal-components analysis, with the best-fitting line going to the origin in the Zijderveld diagrams. In general, maximum angular deviations were generally within low values. Some samples had univectorial behavior, while some showed two or three components. Most of the sections show normal and intermediate polarity directions far from the present GF, while reversed polarities were recorded at San Blas 2, La Serranita 1 and Punta Rubia 2 sites in San Blas Bay as well Saenz cave in the Pali Aike area. They show similar directions observed in nearby sites from southern Patagonia in Argentina and Chile. In fact, previous results obtained at Mylodon, Cueva del Medio, Don Ariel and Las Buitreras caves yielded remanence directions corresponding to obliquely normal, obliquely reversed and reversed field polarity directions with similar VGPs. This situation strengthens the hypothesis of the existence of the Mylodon excursion in southern Patagonia. On the other hand, the presence of intermediate and reverse VGPs in San Blas records and other sites also supports its regional extent in the southern cone of South America. If the presented paleomagnetic features are true GMF behavior, the remarkably PSV record can serve to correlate regional stratigraphies, and to determine relative and absolute chronologies. Besides, if the anomalous directions represent excursions, they may be also used as dating devices, becoming excellent magnetostratigraphic markers for the time-span covered by the paleomagnetic record of the sites presented in this paper.

Comparing Rock Discontinuity Measurements Using Geological Compass, Smartphone Application, and Laser Scanning Methods

To determine stability of rock slopes, discontinuity orientations must be measured accurately. Several methods exist for taking field measurements of discontinuity orientations. The objective of this study was to compare the traditional method of hand measuring discontinuity orientations using a Brunton compass to the more modern methods of measuring discontinuities using smartphone applications and ground-based Lidar laser scanning. The field site is a rock outcrop along Stroubles Road on Price Mountain, in Montgomery County, Virginia. The Price Mountain structure is a doubly plunging anticline exposed in a window in the Pulaski Thrust Sheet. The rock outcrop consists of a Mississippian sandstone mapped as the Upper Price Formation. The site features a set of bedding planes that dip steeply into the cut slope face, yielding toppling failures. In addition, two distinct sets of joints exist creating both planar and wedge failures in the cut slope. Using window mapping, discontinuity orientations were measured along 200 feet (61 meters) of outcrop using a Brunton compass and a smartphone application, along with a laser scan. These measurements were compared using stereonet analyses to determine the relative accuracy of the different methods. The results show a strong agreement between measurements taken with the Brunton compass and the smartphone application. However, the laser scan shows that scanner data needs calibration with field measurements and observations to yield equally good results. Remote sensing methods like laser scanning, such as terrestrial photogrammetry, cannot be used completely independent of traditional field characterization and input from experienced professionals.

Engineering geological and geotechnical investigations along the head race tunnel in Teesta Stage-III hydroelectric project, India

An investigation of the engineering geological properties and geotechnical parameters of rock masses along a horseshoe-shaped head race tunnel (HRT) in the Teesta Stage-III hydroelectric project, Sikkim, India, was carried out to analyze the rock mass properties for optimum support system. The empirical methods, field tests and numerical modeling were employed to determine rock mass properties. Several empirical equations and statistical analysis were performed to obtain the rational and reasonable results. The tunnel passes through different geological formations and critical zones. The field investigations indicate the presence of five joint sets, which contribute towards the development of unforeseen wedges along the tunnel alignment. The attitudes of joints were measured by Brunton compass and analyzed with Dips v.5.1 software. The potential wedge block analysis and factor of safety (FS) were determined using Unwedge v.3.0 software. The rock mass classification, assessment of tunnel stability and necessary support types were carried out with Q, RMR and RMi systems as empirical tunnel support design methods. The numerical method (Phase2 v.6.0) was used to quantify plastic zone and squeezing potential of the tunnel. The installed support systems as per empirical methods were cross-checked by means of numerical modeling, field observations and engineering judgments. According to the results from different methods, 3.0–4.4m rock bolts, shotcrete 0.1–0.15m, wire mesh and final concrete lining were proposed. It was observed that the plastic and deformed zones surrounding the excavation area got appreciably reduced after the recommended support installation.

A Computer Program for Use with Pace and Compass Exercises

Although GPS technology has greatly improved in recent years it is still important to train students in traditional navigation skills with the Brunton compass. In addition to considerable pedagogic value inherent in such training, the compass can serve as a valuable backup to GPS. Within the geosciences the pace and compass traverse has been a common field technique for determining spatial coordinates of features in the field. However, students commonly find it difficult to separate graphical errors inherent in the technique from those associated with field measurements. The Pace program takes user-supplied azimuth and distance data and employs simple vector addition to determine the XY coordinates of successive stations in a traverse. This program provides a way for students to eliminate graphical errors, thereby allowing them to better gauge the true accuracy of their field data. Instructors can also use the program as a valuable means of helping students learn to differentiate between random and systematic errors in their field-data set. Ultimately, students should realize that multiple sources of error exist in most types of data and appreciate the importance of locating and minimizing such errors.

Linking New Hampshire’s Rock Cut Management System with a Geographic Information System

The New Hampshire Department of Transportation (NHDOT) first conducted a Rock Cut Hazard Survey in 1975, which included 182 rock cuts. The program has evolved since 1975 and now incorporates 380 rock cuts and 4 Rock Fall Hazard Rating Systems. Using New Hampshire’s State Planning and Research funding, a research project was initiated with the objective of combining new rock cut data with preexisting data into a geographic information system (GIS). Rock cut point features were collected for every rock cut with the Global Positioning System and were added as a data layer on top of existing data coverage available through the department’s GIS server. A relational database was developed that would store all rock cut data and would be linked to the GIS through a standard language query connect statement. A Brunton compass was used to collect rock cut structural data, and a digital camera was used to photograph every rock cut. The structural data were graphically represented in the GIS in the form of rose diagrams, stereonets, and density plots. A laser profiler was used to collect two-dimensional profiles on selected rock cuts so rock fall simulations could be conducted. The GIS does have limitations, including the network bandwidth, accessibility restrictions, and resource allocation for maintaining current and accurate data. Deployment of an Internet mapping service has been recommended to increase accessibility and to allow all NHDOT users access to the Rock Cut Management System through a web browser.

Teaching Geologic Mapping to High-School Seniors

The best way to teach geologic mapping to a high-school geology class is to actually have them map a given area. To test this hypothesis, I recently arranged for a 12th-grade geology class to spend five weeks in the field collecting data which enabled them to produce a geologic map from a topographic map. Preparatory to going into the field, the students learned mineral and rock identification, the structural geology of folding, the relative resistance of rocks to weathering, strike and dip, how to read and interpret topographic maps and how to use a Brunton compass. During the field experience, groups of students identified rock formations and gathered strike and dip data. Back in the classroom, they prepared a geologic map and cross section using their field data.

Geology and Paleontology Taught by a Conference System

Geology and paleontology at Sarah Lawrence College are taught using a conference system similar to Oxford's tutorial program, where students meet frequently with the instructor in addition to attending regular class meetings. During conference sessions students are able to call on their own special talents and strengths to explore topics in depth, making it much easier for the instructor to deal with the various scientific backgrounds typical of students in courses with no prerequisites. Field work is emphasized and is an integral part of the learning experience. Students spend more than 50 percent of their class time in the field during the fall semester. The field work culminates in a three-day mapping exercise during which students complete a geological map and structural cross section using a Brunton compass, a topographic base map, and an acetate cover sheet. The major goals of the course include: 1) making the subject matter useful to each student, 2) improving the students' scientific literacy, 3) ...

Terrain Models in Field Geology Courses

Terrain “sand table” models provide versatility and economy in the teaching of structural geology and field methods at schools located far from good mapping areas. Use of a terrain model for geologic mapping, combined with exercises in rock description, Brunton compass manipulation, orienteering, and geologic report writing allows students to refine many skills needed for summer field camp. Experience indicates that such laboratory models should only be used as a supplement to numerous field excursions and the study of geologic maps.

A field technique to directly measure river bank erosion

Presently used techniques were found to be unsuitable in monitoring intermediate rates of river bank erosion. Sequential bank profiling from a fixed baseline using a stadia rod for vertical control and another stadia rod, Brunton compass, and metre rule for horizontal control provides a rapid, accurate representation of river bank changes, using inexpensive, readily available equipment.

A Compass and Clinometer Modified for Strucutral Analysis

The Suunto compass and clinometer are precision, hand-held sighting instruments which can easily be modified to make a compact geologic compass particularly useful for measuring orientations of S-surfaces and rake angles of lineations. Modificaitons consist of mounting on a single baseplate the Suunto compass, the clinometer, and a circular spirit level and calibrating to eliminate parallax in angle readings. These modifications result in an instrument which is comparable in cost and in practical accuracy to the Brunton compass but is more versatile, faster, and easier to operate with one hand.

Device for Direct Measurement of True Dip from Apparent Dip

An easily constructed nonmagnetic lightweight device consisting of a small plane surface to which two movable arms are attached has been successfully used to form the true dip plane where only apparent dips are available. Measurement of strike and dip with a Brunton compass using the surface of the device as the true dip surface eliminates additional measurement as well as all calculations. It is also useful where bedding planes are too small to make readings on, as well as on hard rock where only bedding traces are visible. The device has proved to be exceptionally useful where many measurements of cross-strata were required.

Strike-dip indicator

A strike-dip indicator was designed to facilitate rapid determination of the orientation of surfaces in unconsolidated deposits. It is made of aluminum and contains two spirit levels to determine the strike and dip direction. Dip angles are indicated on a graduated arm to the nearest 1/4 degree. Strike and dip direction are obtained with a Brunton Compass used in conjunction with the instrument. A blade is inserted along the surface to be measured and a hinge and swivel are provided for three dimensional leveling prior to obtaining readings.

Palaeomagnetism and Age of Rocks from Easter Island and Juan Fernandez

In 1966 the expedition,’Carousel’ of the Scripps Institution of Oceanography called for three days at Easter Island and for a few hours at Juan Fernandez. The opportunity was taken to collect rock samples of known orientation for the determination of their ages and directions of magnetization. Owing to the shortness of the available time, the investigation was less thorough than was desirable. A Brunton compass was used to orient the samples.

Remanent Magnetism of Carboniferous Limestone

Summary Paleomagnetic data are lacking on Carboniferous limestones of England and during an investigation of iron ores the author found specimens of these limestones that could be measured. An average declination of S 41 W and inclination of minus 29 degrees was determined for the remanent magnetization. This gives a pole position of north 40 degrees latitude and 122 degrees east longitude. Intensity values of remanent magnetizationrangedupwardsto 27.5 x 10demu/cm3. I. Introduction During the course of a study of the magnetism of rocks of ore deposits and associated areas, the author measured the remanent magnetism of a series of specimens of British hematitic iron ore and contiguous Carboniferous limestone. This paper pertains to the remanent magnetism of the Carboniferous limestone ; results on the hematites will be forthcoming. The specimens were collected during the winter of 1959-60, from an area immediately southwest 'of the Lake District of England. Specifically they came from sites located at N 54O, W 3. These locations are on either the Barrow-inFurness or Keswick one inch maps of the Ordnance Survey of Great Britain. The field orientation of the specimens was determined with the aid of a Brunton compass after it had been determined that there were no local anomalous magnetic effects that would effect the orientation of the compass needle. From the oriented specimens oriented discs were obtained that measured three-fourths of an inch in diameter and five-eights of an inch in length. A total of 52 disks were prepared from 19 specimens and of this total 22 disks could be measured from 14 specimens. Corrections for geological dip were made by coring normal to bedding surfaces of specimens collected at one site where dips of 8 were measured. At other sites the beds were considered to be flat lying. The specimens measured are fine- to medium-grained, grey to reddish brown, limestone of Carboniferous age (Smith 1919). The rocks have been locally altered and even more locally have been metasomatically replaced and openings filled by hematite. 2. Experimental and calculated results