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1. Geological Map
Presented By:
Kalpajyoti Mazumdar
4th sem, Department of Earth Ecience,
Assam University, Silchar

2. Content
 Introduction
 Brief history of Geological mapping
 Types of Geological Map
 How geological maps prepared ?
 Field Equipment
 Map scale
 Map key
 Conclusion
 Bibliography

3. Introduction
• What is a Map?
• A map is a picture or representation of the Earth’s
surface, showing how things are related to each other
by distance, direction , and size.
• Maps are a way of showing many things about a
portion of the Earth’s surface on a flat piece of paper
that can be carried and transported easily.
• A map is not a photograph of the Earth’s surface. It
can show many things that a picture can’t show, and
as a result, a map looks different in many ways from a
photograph of the Earth’s surface

4. What is a Geological Map?
• Geological map is a special purpose map made to show
geological features.
• A geologic map is a made of the different types of rocks or
structures that are on the surface of the Earth.
• Geologic maps are used to interpret the structure,
Stratigraphy , Mineralogy, Paleontology, and the historical
record of the Earth’s crust.

6. Brief history of geological mapping
 The map indicating the gold field in Egypt on the 13th century, is the first
recorded attempt in providing graphical geological information.
 In the 16th century D. Owen showed the Carboniferous outcrop in the form
of narrow beds.
 First geological map is known to have been compiled M.Lister at end of the
17th century.
 The first stratigraphic layer by layer geological map is started appearing at
the beginning of the 18th century.
 In India the first geological map was prepared by Dr. Henry Westly Voysey.
 Apt. J D the 1825 and this Herbest prepared the first geological map of the
Himalayan in was published in 1842 for the area between the river Sutlej and
Kali.

7. Types of Geological Mapping
There are 3 major types of Geologic Maps
1. Topographic Maps
2. Structural Maps
3. Cross-section map

8. 1. Topographical Maps:
Topographic maps, show a 3 dimensional world
in 2 dimensions, by using contour lines (lines of
equal elevation).
Topographic maps refer to a graphical
representation of the three-dimensional
configuration of the surface of the Earth.
Moreover, such maps show the size, shape, and
distribution of landscape features.

9. 2. Structural mapping
• Structural mapping is the identification and characterization of structural
expression. Structures include faults, folds, synclines and anticlines and
lineaments. Understanding structures is the key to interpreting crustal
movements that have shaped the present terrain.
• A synoptic view of regional scale is a much different perspective than point
ground observations when trying to map structural elements. Remote sensing
offers this perspective and allows a geologist to examine other reference
ancillary data simultaneously and synergistically, such as geo-magnetic
information.

11. 3. Cross-sectional map
• A cross-sectional map shows the cross-section from the side. The cross-sectional maps
shows the changes along the line shown on the map.
• Cross-section maps or block diagrams is not a map actually but sometimes it is also
considered as a geological map, because of showing data similar to a geological map

14. Some other types of maps

15. Global map of monthly sea surface salinity, May 2022.
NASA's Soil Moisture Active Passive (SMAP) mission

17. Map of the world showing average annual precipitation

19. How Geological maps are prepared?
• The aim of geologic mapping is to create a map which summarizes the
geologic data gathered in the field.
• Every place that an observation is made, a sample is gathered, or any type
od data collection takes place, it is positioned on the map at the appropriate
X – Y coordinates.
• The map can be small scale and show much detail, or be large scale and
generalized.
• Different geologic mapping agencies and authorities have different
standards for the colors and symbols to be used for rocks of different types
and ages.

20. Field
Equipment
A
B
C
D
E
F
G
H
I
J
K

21. Map
scale
• Map scale can be expressed as the ratio or proportion between a
distance on a map and the actual distance on the land surface.
This ratio is called the Representative Fraction (RF). A RF of
1:100,000 indicates that 1 unit of measure on the map represents
100,000 units on the land surface (i.e. , 1 inch = 100,000 inches, 1.58
miles)

26. 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.

27. Bibliography
1. Basics of Geological mapping John W. Barnes, formerly of the Department of
Earth Science ,University of Wales Swansea
2. Standards for Regional Geological Mapping: Procedures and Guidelines for
work processes contented digital attributes for products (part II , part I)
Regional Geology and Geochemistry Department Geological Survey of Ethiopia

28. How to create geological map on
QGIS
Complete guide
• https://youtu.be/I8Wzm2qJsh0