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

20. Hammer and chisels
compass

21. GPS
clinometers

22. scales

23. 
Compass and clinometers

Handless

Tapes

Map cause

Field note book

Acid bottles

Global position system

24. MAP SYMBOLS

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