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Geological mapping

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Pramoda Raj
Pramoda Raj

Geological mapping involves systematically observing and recording rock exposures and structural features in the field to produce maps that show the spatial distribution and relationships of rock units. The document discusses different types of geological maps including reconnaissance, regional, detailed, and specialized maps. It also describes common mapping techniques such as traversing, exposure mapping, drilling, underground mapping, and photo-geology. Field equipment used in mapping includes hammers, chisels, compasses, clinometers, tapes, and notebooks.

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Seminar on GeoloGical mappinG Under the GUidance of Dr.B.SURESH Dos in earth science University of Mysore SUbmitted by Rajesh R 3rd sem geology Dos in earth science University of Mysore
CONTENTS  Introduction  Brief history of geological mapping  Typeof geological map Reconnaissancemaps Regional geological maps Detailed geological maps Specialised maps  Methodsof geological mapping Traversing exposureor green linemapping drilling underground mapping Photo-geology  Measurementsand techniques  Field equipment's  reference  conclusion
introduction A geologic map or geological map isaspecial-purposemap madeto show geological features. Rock unitsor geologic strataareshown by color or symbolsto indicatewherethey areexposed at thesurface. Bedding planesand structural featuressuch asfaults, folds, foliations, and lineationsareshown with strikeand dip or trend and plunge symbolswhich orientationsivethesefeatures' threedimensional geological mapsarethebasisof all geological work, even laboratory work, for it ispointlessto makeadetailed investigation of a specimen whoseprovenanceisuncertain” BarnesBasic geological mapping.
BRIEF HISTORY OF GEOLOGICAL MAPPING  Themap indicating thegold field in Egypt on the13th century, isthefirst recorded attempt in providing graphical geological information  In the16th century D.Owen showed thecarboniferousout crop in the form of narrow beds.  First geological map isknown to havebeen complied M.Lister at theend of the17th century.  Thefirst stratigraphic layer by layer geological map isstarted appearing at thebeginning of the18th century.  In Indiathefirst geological map wasprepared by Dr.Henry Westly Voysey  Capt.JD the1825 and thisHerbest prepared thefirst geological map of theHimalayain waspublished in 1842 for theareabetween theriver Sutlej and kali.
TYPE OF GEOLOGICAL MAPPING  Reconnaissance maps:- are made to find out as much as possible about the geology of an area as quickly as possible. They are usually made at a scale of 1:250 000 or smaller, sometimes very much smaller. Some reconnaissance maps are made by photo geology, that is by interpreting geology from aerial photographs, with only a minimum of work done on the ground to identify rock types and to identify structural features, such as lineaments. Reconnaissance maps have even been made by plotting the main geological features from a light aircraft or helicopter with, again, only brief confirmatory visits to the ground itself.
REGIONAL GEOLOGICAL MAPS  :- should be plotted on a reliable base. Unfortunately, in some countries, geological mapping outstrips topographic coverage when there is a sudden economic interest in a specific area and geologists must then survey the topography themselves. An accurate geological map loses much of its point if superimposed on an inadequate topographic base. Regional geological mapping done on the ground may be supported by systematic photo geology, and it should be emphasised that photo geological evidence is not inferior to information obtained on the ground although it may differ in character.
cannot even be detected on the ground while others can even be more conveniently followed on photographs than in surface exposures .All geological mapping should incorporate any techniques which can help in plotting the geology and which the budget will allow, including geophysics, pitting, auguring, drilling and even the use of satellite images where available.
Detailed geological maps:- Scalesfor detailed geological mapsmay beanything from 1:10 000 and larger. Such mapsaremadeto investigatespecific problemswhich havearisen during smaller-scalemapping, or from discoveriesmade during mineral exploration, or perhapsfor thepreliminary investigation of adam siteor for other engineering projects. In Britain 1:10 000 isnow thescaleused for regional mapsby theGeological Survey to cover thewholecountry, replacing theolder‘6 inchesto the mile’ series(1:10 560)
 Specialised maps:-Specialised maps are many and various. They include large-scale maps of small areas made to record specific geological features in great detail. Some are for research, others for economic purposes, such as open pit mine plans at scales from 1:1000 to 1:2500; underground geological mine plans at 1:500 or larger; and engineering site investigations at similar scales. There are many other types of map with geological affiliations too. They include geophysical and geochemical maps; foliation and joint maps; and sampling plans. Most are superimposed over an outline of the geology, or drawn on transparencies to be superimposed on geological maps, to study their relationship with the solid geology.
METHODS OF GEOLOGICAL MAPPING Traversing:-It is also a method of covering the ground in the detail required by your employer. A traverse is made by walking a more or less predetermined route from one point on the map to another, plotting the geology on the way. Traverses are an excellent way of controlling the density of your observations.
MAPPING TECHNIQUES Traversing •Walking along apredetermined route plotting in thegeology on theway •Thegeology in between traversesis interpolated, using whatever cluescan begleaned from thetopographic map •Thismethod isused predominantly for reconnaissancework •Largeareasof ground can becovered
 Exposure and green line mapping:-Mapping by exposures is the mainstay of much detailed mapping at scales of 1:10 000 and larger. The extent of each exposure, or group of exposures, is indicated on the field map by colouring them in with the appropriate coloured pencil for that rock type or formation. Some geologists go further and mark the limits of the exposure by drawing a line round it, later inked in green, hence green line mapping. Green fades rapidly in the tropics and a fine black dotted line can be substituted.
MAPPING TECHNIQUES ‘Green line’ mapping •Exposuresringed by green lines using avery fine(0.1 mm) nib size •ALLexposuresareportrayed. Thereshould beevidenceon the map that all theground hasbeen covered •When all exposureshavebeen mapped, boundariesbetween the unitscan bedrawn on themap •Theclassic techniquefor 1: 10 000 mapping
MAPPING TECHNIQUES Boundary mapping •Oneof themain aimsin compiling a geological map •Locateaboundary and follow it across themap •Oneof theeasiest methodsof mapping whereexposureisgood •Very effectivein conjunction with aerial photographs • Doesnot work well if exposureispoor
DRILLING it is most commonly employed to locate formations at depth; to confirm their presence in the lack of other evidence; to solve structural problems; and to sample rocks and ores. It is also used to find and exploit water, and of course oil. Basically, there are two kinds of drill:  percussion drilling  and rotary drilling
UNDERGROUND MAPPING Although mapping geology in underground workings, especially in metal minesor in caves, isnot asubject for thissmall book, afew wordsmay beusefully said. Thosethat do haveambitionsfor such projectswould do well to consult Forrester (1964), if only for hisexcellent examplesof coloured underground field sheets, and also Peters(1978). When consulting mapsof underground workings thereisaconvention that the geology in metal mineshasnormally been mapped in thewallsat waist height, or projected to waist height. Thisisbecausethe‘back’ (i.e. the roof) isirregular and often too high to reach or even seeproperly, and the floor iscovered in mud, debris, or even water.
PHOTO-GEOLOGY Photo-geology is the systematic interpretation of geology from aerial photographs. It can be used as a method of geological reconnaissance with only limited ground checking, or as an adjunct to orthodox geological mapping.
MEASUREMENTS AND TECHNIQUES  Measuring strike and dip  Plotting strike and dip  Recording strike and dip  Measuring linear features  Folds  Faults  Thrust and unconformity  joints
Field equipments Hammer and chisels:-Any geologist going into the field needs at least one hammer with which to break rock. Generally, a hammer weighing less than about 3 kg (1 1 lbs) is42of little use except for very soft rocks. Hammering alone is not always the best way to collect rock or fossil specimens. Sometimes a cold chisel is needed to break out a specific piece of rock or fossil. Its size depends on the work to be done. A 5 mm ( 1 inch)4 chisel may be ideal to delicately chip a small fossil free from shale, but to break out large pieces of harder rock a 20–25 mm ( 3 inch) chisel isrequired
Hammer and chisels compass
GPS clinometers
scales
 Compass and clinometers  Handless  Tapes  Map cause  Field note book  Acid bottles  Global position system
MAP SYMBOLS
Geological mapping
Geological mapping
Map Scale Map scalecan beexpressed astheratio or proportion between adistance on amap and theactual distanceon theland surface. Thisratio is called theRepresentativeFraction (RF). A RF of 1:100,000 indicates that 1 unit of measureon themap represents100,000 unitson the land surface(i.e., 1 inch = 100,000 inches- 1.58 miles) Largescaleand small scale A largeamount of confusion iscaused by thetwo terms"largescale" and "small scale". "Largescale" refersto mapson which objectsarerelatively large, "small scale" to mapson which objectsarerelatively small. Large scaleand small scalearesubjectiveterms. For exampleatown planner who isused to working with plansat 1:1000, may consider 1:25 000 a small scalemap, whilean atlascompiler commonly working with maps of scales1:5 000 000 would consider 1:25 000 alargescalemap.
A large scale map of Long Reef Point from a 1:25 000 map,
A SMALL SCALE MAPOF LONG REEF POINT TAKEN FROM A 1: 100 000 MAP
CONCLUSION Geological mapping is the fundamental task of a geologist on the basis of which all subsequent qualitative and quantitative geological studies are carried out leading to understanding of evolution of chosen part of the terrain in space and time. the information is represent graphically on a chosen scale, by use of combination of colours/characters,lines and symbols.
reference www.google.com www.wikipedia.com Basics of geological mapping John W. Barnes formerly of the Department of Earth ScJohn W. Barnes formerly of the Department of Earth Sciences, University of Wales Swansea with Richard J. Lisle Department of Earth, Ocean and Planetary Sciences Cardiff University page- 5 to 198 STANDARDS FOR REGIONAL GEOLOGIC MAPPING: PROCEDURES AND GUIDELINES FOR WORK PROCESSES CONTENTAND DIGITALATTRIBUTES FOR PRODUCTS (PARTII) (PART I) REGIONAL GEOLOGYAND GEOCHEMISTRY DEPARTMENT GEOLOGICAL SURVEY OF ETHIOPIA
Geological mapping

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Geological mapping

  • 1. Seminar on GeoloGical mappinG Under the GUidance of Dr.B.SURESH Dos in earth science University of Mysore SUbmitted by Rajesh R 3rd sem geology Dos in earth science University of Mysore
  • 2. CONTENTS  Introduction  Brief history of geological mapping  Typeof geological map Reconnaissancemaps Regional geological maps Detailed geological maps Specialised maps  Methodsof geological mapping Traversing exposureor green linemapping drilling underground mapping Photo-geology  Measurementsand techniques  Field equipment's  reference  conclusion
  • 3. introduction A geologic map or geological map isaspecial-purposemap madeto show geological features. Rock unitsor geologic strataareshown by color or symbolsto indicatewherethey areexposed at thesurface. Bedding planesand structural featuressuch asfaults, folds, foliations, and lineationsareshown with strikeand dip or trend and plunge symbolswhich orientationsivethesefeatures' threedimensional geological mapsarethebasisof all geological work, even laboratory work, for it ispointlessto makeadetailed investigation of a specimen whoseprovenanceisuncertain” BarnesBasic geological mapping.
  • 4. BRIEF HISTORY OF GEOLOGICAL MAPPING  Themap indicating thegold field in Egypt on the13th century, isthefirst recorded attempt in providing graphical geological information  In the16th century D.Owen showed thecarboniferousout crop in the form of narrow beds.  First geological map isknown to havebeen complied M.Lister at theend of the17th century.  Thefirst stratigraphic layer by layer geological map isstarted appearing at thebeginning of the18th century.  In Indiathefirst geological map wasprepared by Dr.Henry Westly Voysey  Capt.JD the1825 and thisHerbest prepared thefirst geological map of theHimalayain waspublished in 1842 for theareabetween theriver Sutlej and kali.
  • 5. TYPE OF GEOLOGICAL MAPPING  Reconnaissance maps:- are made to find out as much as possible about the geology of an area as quickly as possible. They are usually made at a scale of 1:250 000 or smaller, sometimes very much smaller. Some reconnaissance maps are made by photo geology, that is by interpreting geology from aerial photographs, with only a minimum of work done on the ground to identify rock types and to identify structural features, such as lineaments. Reconnaissance maps have even been made by plotting the main geological features from a light aircraft or helicopter with, again, only brief confirmatory visits to the ground itself.
  • 6. REGIONAL GEOLOGICAL MAPS  :- should be plotted on a reliable base. Unfortunately, in some countries, geological mapping outstrips topographic coverage when there is a sudden economic interest in a specific area and geologists must then survey the topography themselves. An accurate geological map loses much of its point if superimposed on an inadequate topographic base. Regional geological mapping done on the ground may be supported by systematic photo geology, and it should be emphasised that photo geological evidence is not inferior to information obtained on the ground although it may differ in character.
  • 7. cannot even be detected on the ground while others can even be more conveniently followed on photographs than in surface exposures .All geological mapping should incorporate any techniques which can help in plotting the geology and which the budget will allow, including geophysics, pitting, auguring, drilling and even the use of satellite images where available.
  • 8. Detailed geological maps:- Scalesfor detailed geological mapsmay beanything from 1:10 000 and larger. Such mapsaremadeto investigatespecific problemswhich havearisen during smaller-scalemapping, or from discoveriesmade during mineral exploration, or perhapsfor thepreliminary investigation of adam siteor for other engineering projects. In Britain 1:10 000 isnow thescaleused for regional mapsby theGeological Survey to cover thewholecountry, replacing theolder‘6 inchesto the mile’ series(1:10 560)
  • 9.  Specialised maps:-Specialised maps are many and various. They include large-scale maps of small areas made to record specific geological features in great detail. Some are for research, others for economic purposes, such as open pit mine plans at scales from 1:1000 to 1:2500; underground geological mine plans at 1:500 or larger; and engineering site investigations at similar scales. There are many other types of map with geological affiliations too. They include geophysical and geochemical maps; foliation and joint maps; and sampling plans. Most are superimposed over an outline of the geology, or drawn on transparencies to be superimposed on geological maps, to study their relationship with the solid geology.
  • 10. METHODS OF GEOLOGICAL MAPPING Traversing:-It is also a method of covering the ground in the detail required by your employer. A traverse is made by walking a more or less predetermined route from one point on the map to another, plotting the geology on the way. Traverses are an excellent way of controlling the density of your observations.
  • 11. MAPPING TECHNIQUES Traversing •Walking along apredetermined route plotting in thegeology on theway •Thegeology in between traversesis interpolated, using whatever cluescan begleaned from thetopographic map •Thismethod isused predominantly for reconnaissancework •Largeareasof ground can becovered
  • 12.  Exposure and green line mapping:-Mapping by exposures is the mainstay of much detailed mapping at scales of 1:10 000 and larger. The extent of each exposure, or group of exposures, is indicated on the field map by colouring them in with the appropriate coloured pencil for that rock type or formation. Some geologists go further and mark the limits of the exposure by drawing a line round it, later inked in green, hence green line mapping. Green fades rapidly in the tropics and a fine black dotted line can be substituted.
  • 13. MAPPING TECHNIQUES ‘Green line’ mapping •Exposuresringed by green lines using avery fine(0.1 mm) nib size •ALLexposuresareportrayed. Thereshould beevidenceon the map that all theground hasbeen covered •When all exposureshavebeen mapped, boundariesbetween the unitscan bedrawn on themap •Theclassic techniquefor 1: 10 000 mapping
  • 14. MAPPING TECHNIQUES Boundary mapping •Oneof themain aimsin compiling a geological map •Locateaboundary and follow it across themap •Oneof theeasiest methodsof mapping whereexposureisgood •Very effectivein conjunction with aerial photographs • Doesnot work well if exposureispoor
  • 15. DRILLING it is most commonly employed to locate formations at depth; to confirm their presence in the lack of other evidence; to solve structural problems; and to sample rocks and ores. It is also used to find and exploit water, and of course oil. Basically, there are two kinds of drill:  percussion drilling  and rotary drilling
  • 16. UNDERGROUND MAPPING Although mapping geology in underground workings, especially in metal minesor in caves, isnot asubject for thissmall book, afew wordsmay beusefully said. Thosethat do haveambitionsfor such projectswould do well to consult Forrester (1964), if only for hisexcellent examplesof coloured underground field sheets, and also Peters(1978). When consulting mapsof underground workings thereisaconvention that the geology in metal mineshasnormally been mapped in thewallsat waist height, or projected to waist height. Thisisbecausethe‘back’ (i.e. the roof) isirregular and often too high to reach or even seeproperly, and the floor iscovered in mud, debris, or even water.
  • 17. PHOTO-GEOLOGY Photo-geology is the systematic interpretation of geology from aerial photographs. It can be used as a method of geological reconnaissance with only limited ground checking, or as an adjunct to orthodox geological mapping.
  • 18. MEASUREMENTS AND TECHNIQUES  Measuring strike and dip  Plotting strike and dip  Recording strike and dip  Measuring linear features  Folds  Faults  Thrust and unconformity  joints
  • 19. Field equipments Hammer and chisels:-Any geologist going into the field needs at least one hammer with which to break rock. Generally, a hammer weighing less than about 3 kg (1 1 lbs) is42of little use except for very soft rocks. Hammering alone is not always the best way to collect rock or fossil specimens. Sometimes a cold chisel is needed to break out a specific piece of rock or fossil. Its size depends on the work to be done. A 5 mm ( 1 inch)4 chisel may be ideal to delicately chip a small fossil free from shale, but to break out large pieces of harder rock a 20–25 mm ( 3 inch) chisel isrequired
  • 23.  Compass and clinometers  Handless  Tapes  Map cause  Field note book  Acid bottles  Global position system
  • 27. Map Scale Map scalecan beexpressed astheratio or proportion between adistance on amap and theactual distanceon theland surface. Thisratio is called theRepresentativeFraction (RF). A RF of 1:100,000 indicates that 1 unit of measureon themap represents100,000 unitson the land surface(i.e., 1 inch = 100,000 inches- 1.58 miles) Largescaleand small scale A largeamount of confusion iscaused by thetwo terms"largescale" and "small scale". "Largescale" refersto mapson which objectsarerelatively large, "small scale" to mapson which objectsarerelatively small. Large scaleand small scalearesubjectiveterms. For exampleatown planner who isused to working with plansat 1:1000, may consider 1:25 000 a small scalemap, whilean atlascompiler commonly working with maps of scales1:5 000 000 would consider 1:25 000 alargescalemap.
  • 28. A large scale map of Long Reef Point from a 1:25 000 map,
  • 29. A SMALL SCALE MAPOF LONG REEF POINT TAKEN FROM A 1: 100 000 MAP
  • 30. CONCLUSION Geological mapping is the fundamental task of a geologist on the basis of which all subsequent qualitative and quantitative geological studies are carried out leading to understanding of evolution of chosen part of the terrain in space and time. the information is represent graphically on a chosen scale, by use of combination of colours/characters,lines and symbols.
  • 31. reference www.google.com www.wikipedia.com Basics of geological mapping John W. Barnes formerly of the Department of Earth ScJohn W. Barnes formerly of the Department of Earth Sciences, University of Wales Swansea with Richard J. Lisle Department of Earth, Ocean and Planetary Sciences Cardiff University page- 5 to 198 STANDARDS FOR REGIONAL GEOLOGIC MAPPING: PROCEDURES AND GUIDELINES FOR WORK PROCESSES CONTENTAND DIGITALATTRIBUTES FOR PRODUCTS (PARTII) (PART I) REGIONAL GEOLOGYAND GEOCHEMISTRY DEPARTMENT GEOLOGICAL SURVEY OF ETHIOPIA