Basic Principles Of Geological And Thematic Mapping
Basic principles of geologicaland thematic mappingPavel Hanžl and Kryštof Verner (eds.)with co-authorsDavid Buriánek, Jiří Šíma, Jana Janderková, Eva Kryštofová,Martin Paleček, Tomáš Hroch, Karel Martínek, Leta Megerssa,Kristýna Hrdličková and Václav MetelkaCzech Geological SurveyGeological Survey of Ethiopia2018
Reviewed by Ameha Atnafu Muluneh, Addis Ababa University, EthiopiaLanguage editor: Matůš Sadloň Czech Geological Survey, Geological Survey of EthiopiaISBN 978-80-7075-951-6
ContentsPreface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51) Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.1 Geological map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.2 Types of geological and thematic maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82) Topographic base map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.1 Characteristics of the topographic map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.2 Coordinate systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.3 Magnetic declinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123) Remote sensing in geological mapping . . . . . . . . . . . . . . . . . . . . . . . . . . 133.1 Digital elevation models (DEMs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133.2 Tectonic interpretation of remotely sensed data . . . . . . . . . . . . . . . . . . . . . . . . . 153.3 Optical imagery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164) Parts of the geological map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204.1 Geological map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214.2 Legend (Key) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214.3 Text information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.4 The lithostratigraphic scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.5 The geological cross-section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234.6 List of authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234.7 Summary of the geological units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234.8 Map sheet index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235) Data source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245.1 Field data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245.2 Laboratory data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255.3 Palaeontology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285.4 Data archive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296) Geological field techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316.1 Localization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316.2 Rock and lithological description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336.3 Tectonics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346.4 Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396.5 Illustrations and photographs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397) Compilation of geological map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417.1 Legend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
IV7.27.37.4Elements of geological map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42The lithostratigraphic scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46Fair copy map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 468) Explanation notes to geological map . . . . . . . . . . . . . . . . . . . . . . . . . . . 498.1 Title page, contents and abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498.2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498.3 Main body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508.4 Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 548.5 Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549) Hydrogeological map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559.1 Components of hydrogeological map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559.2 Hydrochemical map and scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 599.3 Data for hydrogeological mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 609.4 Explanatory notes to the hydrogeological map . . . . . . . . . . . . . . . . . . . . . . . . . . 6510) Geological risks and geomorphology map . . . . . . . . . . . . . . . . . . . . 6910.1 Desktop study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6910.2 Field data collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7010.3 Synthesis and transformation of data to general geo-hazard map . . . . . . . . 7210.4 Explanatory note to the geo-hazard map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7211) Soil Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7511.1 Soil survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7511.2 Soil description and classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7611.3 Compilation of soil map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78Appendixes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81Appendix 1Symbols used in build of geological index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81Appendix 2The most common geological map symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87Appendix 3Rocks classification and lithological description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88Appendix 4Symbology in hydrogeological map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101Appendix 5Symbology in geohazard map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106Appendix 6Recommended codes for the Reference Soil Groups, qualifiers and specifiers . . . . 107
VLIST OF FIGURESFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10Fig. 11Fig. 12Fig. 13Fig. 14Fig. 15Fig. 16Fig. 17Fig. 18Explanation of latitude and longitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Magnetic deviation δ from geographic north . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Shield volcano Dema’ali Terara, Afar depression, NE Ethiopia.Note NW striking normal faults of Red Sea Rift system.Map is 40 km wide (multidirectional shaded relief mapgenerated from ASTER DEM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14An example of granitoid intrusion (rounded body bottom centre)into folded Proterozoic metasediments. 60 km south of Axum,northern Ethiopia, optical satellite imagery in true color,image is 15 km wide ( 2018 DigitalGlobe by Google). . . . . . . . . . . . . . . . . . . . . . . . . . 14NNE striking normal fault escarpments of the Main EthiopianRift system, east of Dobi Graben, Afar Depression, NE Ethiopia. . . . . . . . . . . . . . . . . . 16NW striking Dobi Graben normal fault escarpments, which are partof the Red Sea Rift system, Afar Depression, NE Ethiopia.Note also salt deposits in the graben basin and small alluvial fan (left). . . . . . . . . . 16Diagram showing atmospheric transmission vs. electromagneticwavelength, position of Landsat and ASTER spectral bands areindicated (NASA/USGS). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Schematic layout of the sheet of the geological map. . . . . . . . . . . . . . . . . . . . . . . . . . . 20An example of a field documentation card usedby the Czech Geological Survey in Mongolia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Diagram of the tables and their relationships in the databaseof geological reference points. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30The principle of measuring the orientation of linear and planarstructures and their presentation on the geological map. . . . . . . . . . . . . . . . . . . . . . . 34Projection of N–S striking and 50 W dipping plane.Projection of a line plunging 50 to the west (after Rowland et al. 2013). . . . . . . . . 38An example of a sample card used by CGS in Mongolia. . . . . . . . . . . . . . . . . . . . . . . . . 39An example of a sample label used for geochemical prospectionin Lesser Caucasus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39An example of outcrop illustration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Schematic expression of the V-rule in block diagrams and maps. . . . . . . . . . . . . . . . 48Idealised layout of Geo-hazard map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
VIList of TablesTab. 1Tab. 2Tab. 3Tab. 4Tab. 5Tab. 6Tab. 7Tab. 8Tab. 9Tab. 10Tab. 11Tab. 12Tab. 13Landsat spectral bands, wavelengths and applications. . . . . . . . . . . . . . . . . . . . . . . . . 17Characteristics of the equal-area projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37Principles of the creation of a geological indexfor various kinds of rocks, for symbols see appendix 1 . . . . . . . . . . . . . . . . . . . . . . . . . . 45Structure of the legend table for further GIS processing . . . . . . . . . . . . . . . . . . . . . . . . 46Borehole inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Spring inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62Dug well inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62Water hole inventory (a typical water point in desert areasin a dry wadi bed) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63Field equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63Assessment of water resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67The example of the soil profile description – Dystric Nitisol(Profile ID DE164) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77Survey intensity versus scale and sampling density(according to Dent and Young, 1981) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79Type of soil survey versus scale, purpose and methods used(according to Dent and Young, 1981) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
5PrefaceThis guidebook has been compiled in aid of field geological and thematic mappingactivities at 1 : 50,000 scale. In practice, the geological maps should be readable andconsistent, which requires a series of steps and a logical build-up to realize such mapoutputs.The guidebook has been prepared based on the experience of joint field mappingactivities of geologists from the Czech Geological Survey and Geological Survey ofEthiopia between 2015 and 2018 as a result of development projects funded by the CzechDevelopment Agency in the framework of the Development Cooperation Program of theCzech Republic in Ethiopia.These projects were designed to assess geological and environmental hazards basedon geological and related geo-scientific maps. An effort has been made to maintain thetraditional techniques in the field of geological survey and research combined with recentadvances in geoscience methods and approaches. These methods and approaches willcontribute to the comprehensive knowledge of geological environment in Ethiopia withmany practical applications.This manual is not intended to replace the standard field geological mappingguidebooks and other locally adopted standards, but rather complement it by bridging withthe current demand of users. It is strongly believed that the wider professional communitywill benefit from the use of this guidebook.Kryštof Verner
1) IntroductionGeological mapping is a step-by-step process, which culminates in a compilation ofa geological map. Up on completion of the geological map, applied maps of variousthematic objectives are more efficiently compiled. The objectives of basic geologicalmapping are to describe and depict the geological composition and structure in a particulararea and subsequently to serve as the basis for depicting mineral occurrences, prognosticevaluation of industrial and non-industrial raw materials, groundwater resourcesassessment and delineation of geological hazards and geological factors affecting theenvironment.Libraries and internet are full of texts about field, graphical, laboratory or computertechniques on how to collect, process and publish geological data. However, geologicalmapping cannot be learnt in lecture halls or in laboratories alone. It should be stronglysupplemented with precise field observation where also continued experience is gainedfrom every natural encounter in the process. Geological mapping covers wide spectrumof techniques from natural science to field and laboratory data analysis, handcraft, andimagination and curiosity and practicality. Any two geological maps cannot be identical aseach geologist reflects different style and expression of his viewpoint, making geologicalmapping also kind of an art.The data gathered and the maps compiled are normally intended to serve the needsof the state and public administration, in particular for decision making when planningcivil works, and formulating policies on energy, minerals resources and environmentalprotection. These data are also made available for use by educational establishments,museums, foundations, and public service organizations, as well as by the private sector.The geological maps can be used for academic reasons (how our planet and life wereformed) but in fact geological maps are essential for economic development not only ofindividual countries but the whole continents.1.1 Geological mapGeological map is a scaled-down representation and interpretation of the structure ofselected area of the upper part of the Earth crust usually drawn on the topographic basemap. Geological map shows (using various colours and symbols) the distribution ofdifferent kinds of rocks, and boundaries between them that would be seen on the Earthsurface if the soils were removed.The function of geological and derived maps is: t o explore natural resources (raw materials, groundwater, surface waters, geothermalenergy, etc.). t o locate rocks of particular age, lithology, structure . t o reconstruct geological history of an area. t o estimate composition and character of soils. t o identify geological hazards.
8G eoscience mapping guidebook to estimate physical parameters of rocks for engineering geology. to locate/identify sites with bedrocks suitable for waste disposal. to solve theoretical and applied problems leading to advances in geology and the earthsciences in general. to teach geology and related disciplines.1.2 Types of geological and thematic mapsGeoscience maps are commonly divided according to scale and purposes.Division of geological maps according to the scale: 1 : 10,000,000 and smaller – maps of entire continents or the Earth on a single sheet; 1 : 1,000,000 to 1 : 5,000,000 – synoptic maps of continents or countries; 1 : 500,000 – maps of countries, provinces or states; 1 : 200,000 and 1 : 250,000 – regional maps; 1 : 25,000 and 1 : 50,000 – detailed geological maps in well-investigated countries; 1 : 10,000 and larger – standard scale for field surveying and detailed investigation.Purposes of geological maps are closely related to their scale. While maps of smallerscale provide overview information about large geological units and regional tectonics,maps of larger scales illustrate distribution of rocks and specific geological features ina greater detail.According to the content of maps, the following can be distinguished: Geological base map depicts distribution of the geological units and rocks includingthe Quaternary cover. Usually at a scale of 1 : 25,000 to 1 : 75,000. Geological map of the bedrock (solid) depicts pre-Quaternary geological units in themapped area. Tectonic map shows the orientation and character of lithotectonic units and tectonicfeatures governing the geological structure of the mapped area.The described maps are the base for derived and specialized maps, which could be: Geophysical map. Geochemical map. Map of mineral resources. Hydrogeological map. Map of engineering-geological zoning. Map of geodynamic phenomena. Soil map.
2) Topographic base map2.1 Characteristics of the topographic mapA topographic map provides information on the existence, location, and the distancebetween natural and human-made features on the Earth’s surface. It also indicatesvariations in the terrain, heights of natural features, and the extent of vegetation cover.Therefore, topographic base maps have many purposes, but the prime purpose is to givea graphical two-dimensional representation of the defined portion of the Earth’s surface.The International Cartographic Association defines Topographic Maps as follows:Topographic maps are maps of various scales which incorporate variety of information.The basic coverage (state large-scale map series) is based on measurements done in thefield and/or from aerial photographs. Derived topographical maps (of medium and smallscales) are prepared by reduction and generalization from the original basic maps.In short, it can be said that a topographic map is a graphical representation of thethree-dimensional configuration of the Earth’s surface in two dimensions. It shows thesize, shape and distribution of landscape features, and presents the horizontal and verticalpositions of those represented features. The features in topographic maps can be dividedinto four major groups:Relief: Depicted with contour lines or by shaded relief. A contour line is a line joining points of equal elevation on a surface. Elevations aregiven in meters (or feet) above mean sea level. Every point along a contour line hasthe same exact elevation. Contour lines can never cross each other. A contour linemust close on itself. Some contour lines will have their elevation marked next to them,but not in all cases. In order to calculate the height of any contour line, you need toknow the contour interval. An easy way to recognize real world slopes on the map isto think of the distance between contour lines on the topographic map where the linesrepresent certain constant elevation value. If the distance between contours is very farapart, it indicates a gradual increase in elevation and hence low slope or flat terrain. Ifthe lines are on the other hand too close to each other, the change in elevation occursvery quickly, indicating a steep slope or terrain. A shaded relief is a specific type of terrain representation that uses colours and shadingto show heights and features on the map. Shading on a topographic map is used to give ita more realistic view. Mountains actually look like mountains instead of just contour lines.Water features: they represent oceans, lakes, rivers, streams, swamps, springs etc. A rivernetwork is a mandatory feature that makes it easy to navigate the map.Vegetation: they represent wooded and cleared areas. Topography for geological maps isusually used without forests, because the green colour of forests would distort the coloursof individual geological unities.
G eoscience mapping guidebookCultural features: they represent all the human-made features: buildings, roads, railroads,land boundaries, etc.Topographic maps usually show a geographic graticule (a network of longitude andlatitude lines on a map or chart that relates points on a map to their true locations on theEarth) and a coordinate grid (network of parallel and perpendicular lines superimposedon a map and used for reference) for better finding of relative and absolute positions ofmapped features.2.2 Coordinate systemsCoordinate systems are frameworks that are used to define unique positions. Thecoordinate system that is most commonly used to define locations on the threedimensional Earth is called the geographic coordinate system. It is a three-dimensionalreference system that locates points on the Earth’s surface. The unit of measure is usuallydecimal degrees. A point is described by two coordinate values: latitude and longitude(Fig. 1). Latitude is defined as the angle formed by the intersection of a line perpendicularto the Earth’s surface at a point and the plane of the Equator. Latitude values range from–90 to 90 degrees. Points situated north of the Equator have positive latitude values,while points lying south have negative values.Lines of latitude are also called parallels because a particular value of latitude formsa circle parallel to the Equator. A meridian is formed by a plane that passes throughthe point and the North and South poles. The longitude value is defined by the anglebetween that plane and a reference plane. The reference plane is known as the primemeridian. The most common prime meridian passes through Greenwich, United Kingdom.Longitude values range from –180 to 180 degrees with negative values lying west ofprime meridian.N ( )80 E 55 NLatitude10W (–)E ( )55 Latitude80 Longitude0206080LongitudeS (–)Figure 1. Explanation of latitude and longitude EPEK 10.0.0/spatl/src/art/0sbp5004.gif).
T opographic base mapA projected coordinate system is a two-dimensional representation of the Earth. Ituses Cartesian coordinates based on linear units of measure. It is based on a sphericalearth model and its coordinates are converted to x, y coordinates on the flat projection.The intersection of the x and y axes is the origin and usually has coordinates of(0, 0). The values above the x axis are positive, and the values below the x axis are negative.The lines parallel to the x axis are equidistant from each other. The values to the rightof the axis are positive, and the values to the left of the y axis are negative. The linesparallel to the y axis are equidistant. Mathematical formulas are used to convert a threedimensional geographic coordinate system to a two-dimensional flat projected coordinatesystem. The transformation is referred as a map projection.Map projections are classified by the projection surface used, such as conic,cylindrical, and planar surfaces. Depending on the projection used, different spatialproperties will appear distorted. Projections are designed to minimize the distortionof one or two of the data’s characteristics: the distance, area, shape, direction, ora combination of these properties might not be accurate representations of the databeing modelled.There are several types of projections available. While most map projections attemptto preserve some accuracy of the spatial properties, there are others that attempt tominimize the overall distortion. The most common types of map projections include: E qual area projections preserve areas and distort shape, angle, and scale. C onformal projections preserve angles; the area of the map is distorted. Conformalprojection includes Transverse Mercator projection. Equidistant projections maintain the scale along one or more lines, or from one ortwo points to all other points on the map. If you go outside the data set, the scale willbecome more distorted.Ethiopian topographic maps use projected coordinate system Adindan / UTM zone37N with parameters:WKIDProjectionFalse EastingFalse NorthingCentral MeridianScale FactorLatitude Of OriginLinear Unit MeterGeographic Coordinate SystemAngular UnitPrime MeridianDatumSpheroidSemi-major AxisSemi-minor AxisInverse Flattening20137Transverse Mercator5000000390,99960–1GCS AdindanDegree (0,0174532925199433)Greenwich (0,0)D AdindanClarke 1880 RGS6378249,1456356514,87293,46511
12G eoscience mapping guidebook2.3 Magnetic declinationsTrue north is a geographical direction represented on maps and globes by lines oflongitude. Each line of longitude represents direct north and south travel. Compass, on theother hand, direct you to magnetic north. It is a point in the arctic regions of Canada thatis continually shifting location based on the activity of the Earth’s magnetic fields. Thereis a difference between true north on a map and the north indicated by your compass. Thatdifference is called the magnetic declination and is measured by the angle between truenorth and magnetic north when plotted on a map. If the magnetic north deviates from thegeographic to the right, it declares a positive deviation (δ) called declination angle (Fig. 2),if to the left, it becomes negative. If both directions match, the declination is 0 degrees,and if they are exactly opposite, the declination is 180 degrees.Magnetic declinations vary from place to place, depending on the intensity of theEarth’s magnetic fields. Magnetic declinations in Ethiopia were between 0 25’ and 2 41’ in 2017. The accurate calculation of the magnetic declination value for a particularlocation in Ethiopia can be used by the service at: https://www.ngdc.noaa.gov/geomag-web/NgNm 027090180Figure 2. Magnetic deviation δ from geographic north (https://en.wikipedia.org/wiki/File:Magnetic declination.svg).Further readingAnsonm R. W., Ormeling F. J. (1993): Basic cartography for students and technicians.Published on behalf of the International Cartographic Association by Elsevier AppliedScience Publishers, Science, 212 pp.Robinson A. H., Morrison J. L., Muehrcke P. C., Kimerling A. J., Guptill S. C. (2007):Elements of Cartography, 6th Edition. Willey. 688 pp.Brewer A. C. (2015): Designing Better Maps: A Guide for GIS Users 2nd Edition. EsriPress Edition. 250 pp.Imhof E. (2007): Cartographic Relief Presentation. Esri Press Classics.Rowland J. B. (1955): Features shown on topographic maps. USGS Circular 368.Slocum A. T., McMaster R. B., Kessler F., Howard H. H. (2009): Thematic Cartographyand Geovisualization, 3rd Edition.https://en.wikipedia.org/wiki/Magnetic declination
3) Remote sensing in geological mappingImplementation of remotely sensed data and their interpretation can provide a cost effectivemethod for geological mapping purposes. Most of the Earth s surface is covered by digitalelevation model (DEM) data, Landsat, Aster and other satellite imagery, which are freelyavailable. The aim of this contribution is to provide basic information on data types,which could be used for geological interpretation. Morphology could be easily visualizedusing DEMs in the form of coloured elevation maps combined with shaded relief. Also,Landsat TM (Thematic Mapper, ETM – Enhanced Thematic Mapper, ETM ) band 5and panchromatic band, and radar images (such as Radarsat or ERS – European RemoteSensing satellite) can help to understand morphology. Some lithologies (rock types) couldbe identified from morphology, but DEM is mainly u
Geological mapping is a step-by-step process, which culminates in a compilation of a geological map. Up on completion of the geological map, applied maps of various . to identify geological hazards. 1) IntroductIon to estim
GEOLOGICAL SURVEY SELECTED GEOLOGICAL SURVEY, U.S. BUREAU OF MINES, AND ALASKA DIVISION OF GEOLOGICAL AND GEOPHYSICAL SURVEYS REPORTS AND MAPS ON ALASKA RELEASED DURING 1978, INDEXED BY QUADRANGLE BY Edward H. Cobb Open-file Report 79-706 1979 This report is preliminary and has not been edited or reviewed for conformity with
hydrogeological and engineering geological mapping) o Detailed geological mapping of the direct area of the route (structural geological, hydro-geological and engineering geological mapping) o Test pits, test shafts and outcrops (exc
AER/AGS Special Report 101 (October 2015) 1 Introduction K.E. Maccormack1, L.H.Thorleifson2, R.C. Berg3, and H.A.J. Russell4 1 Alberta Geological Survey 2 Minnesota Geological Survey 3 Illinois State Geological Survey 4 Geological Survey of Canada Abstract The objective of this year’s 3D workshop is to
Geological time is vast, and Earth has changed tremendously during this time. Even though most geological processes are very, very slow, the vast amount of time that has passed has allowed for the formation of extraordinary geological features, as shown in Figure 19.1. We have numerous ways of measuring geological time.
Geological Timescale 1 Geological Timescale - for printing and display along a wall Geological timescale background information The geological timescale is one of the major achievements of geoscience over the last two centuries. The timescale subdivides the 4.6 billion years since the planet formed into a series of time units (e.g.
veys reports and maps on Alaska released during 1974, indexed by quadrangle: U.S. Geological Survey Open-file Report 75-128, 46 p. Cobb, E. H., 1976, Geological Survey and selected U.S. Bureau of Mines and Alaska Division of Geological and Geophysical Sur veys reports and maps on Alaska released during 1975: U.S. Geological Survey Open-file .
B. Explanation of Program Numbers for Geological and Geophysical Programs Released geological and, geophysical and related reports are listed alphabetically by program number and company code. Upon approval of an application to conduct a geophysical or geological program, a unique program number is assigned to the project by the regulator.
Alfredo López Austin). Co-Edited Volume: Art and Media History –––Modern Art in Africa, Asia and Latin America: An Introduction to Global Modernisms. Boston: Wiley-Blackwell, 2012 (Elaine O’Brien, editor; Everlyn Nicodemus, Melissa Chiu, Benjamin Genocchio, Mary K. Coffey, Roberto Tejada, co-editors). Exhibition Catalogs ––– “Equivocal Documents,” in Manuel Álvarez Bravo (c
