Geology report by jitu

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Prepared By: JitendraPd. Gupta
Geology re
1. INTRODUTION
The geological field visit to Malekhu was organized by the Department of Civil
Engineering under Asian Institute Of Technology & Management, in order to
accustom knowledge about the geological structures, their engineering
significance and distribution of different rocks, soil types and study of mass
movement activities. The time duration being three days from 16th to 18th Asadh,
2072 was spend in geological field study in Malekhu, 75 Km. South-west from
Kathmandu.
2. Requirement of Course
Engineering geology is defined as the branch of geology which deals with the
application of geological knowledge in the field of civil engineering for the
construction of infrastructure such as roads, bridges, dam, tunnel etc.
Engineering geology is defined in the statues of IAEG as the science devoted to
investigation, study and solution of different types of engineering and
environmental problem which arises as the result of interaction between the
geology and the work or activities of man, as well as the prediction and
development of measures for prevention remediation of geological hazards.
2.1.1 Importance of engineering geology in the field of civil engineering
Geology in civil engineering concerned with the engineering behavior of earth
materials. It includes investigating existing subsurface conditions and materials;
assessing risks posed by site conditions; designing earthworks and structure
foundations; and monitoring site conditions, earthwork and foundation
construction.
A typical Geo-technical engineering project begins with a site investigation of soil,
rock, fault distribution and bedrock properties on and below an area of interest to
determine their engineering properties including how they will interact with, on or
in a proposed construction. Site investigations are needed to gain an
understanding of the area in or on which the engineering will take place.
Investigations can include the assessment of the risk to humans, property and
the environment from natural hazards such as earthquakes, landslides,
sinkholes, soil liquefaction, debris flows and rock falls.
2.2.2 Geological and Mechanical Principles
o Geological time
o Rock forming minerals
o Rock types, Soil Types
o Mechanical fundamentals for Engineering Geology
o Soil and rock properties

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2.2.3 Geological Structure Analysis
o Geological structures (faults, folds)
o Discontinuities
o Hemispherical projection (basics and borehole analysis)
2.2.4 Applied Engineering Geology
o Landslides classification for slopes in rock and soil
o Mass movement in rock
o Mass movement in soil
o Excavation Principles in Rock and Soil
2.2.5 Engineering Geology in Practice
o Site characterization and investigation techniques
o Case histories and examples
3. LOCATION OF STUDY AREA
The study site lies on the Malekhu river banks, which extends from its confluence
to the Trishuli River to about 2.5 Km. upstream. The Site itself is called Malekhu
which lies on 71 Km. towards south-west along the Prithivi Highway, in Dhading
district, Central Nepal.
The site was selected due to availability of different rocks, the river morphology,
natural topography in small extent of area and different types of mass movement
along the route.
The study site is easily accessible from the Kathmandu valley, a three hours bus
travel along the Prithivi Highway from Thankot can easily take us to site. The
study trip was facilitated by lodging and fooding at the Malekhu chowk.
4. OBJECTIVES OF FIELD STUDY
The main objective of the geological field trip was to learn the basic geotechnical
skills in civil engineering regarding river morphology, site investigation, landslide
and petrology. The study aimed at learning general tactics regarding
identification of rocks determining their major chemical contents, determining the
various geotechnical parameters such as attitude of rock bedding and the
observation of various physical features regarding river channel morphology and
landslides
The main objectives of our field visit were: -
 Measurement of dip and strike
 Study of bedding foliation
 Handling of compass for documentation of Engineering geological data
 Study of landslides
 Study of morphology of river channel
 Rock identification in the field

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 Identification of geological units of the Lesser Himalaya and Kathmandu Nappe
 Engineering geological studies along the large scale geological discontinuity
(The Mahabharat Thrust)
 Study of the rock slope along the road corridor
 To know the rock mapping techniques of the rock outcrops
5. METHODOLOGY
The geological field study of the ascertained area was carried out in the following
ways.
 Field reconnaissance and geological traverse of the study site.
 Sketch of the field topography and rocks.
 Photographs of the field topography and rocks.
 Description of the field topography and rocks.
The study team of students were accompanied and guided by our respected
teachers during the field study. Traversing was done along the study site and the
rock samples were observed, the attitude parameters of bedding planes were
obtained by the use of Brunton Compass. The idea obtained was noted and
photographs of remarkable spot were taken. A firm blow of hammer check the
strength and rock types (igneous, metamorphic and sedimentary) were observed.
6. MEASUREMENT OF PLANAR FEATURE OF ROCK (Chainage about 75
m from old bridge upstream in the Malekhu Khola)
6.1 Rock outcrops and exposures
These are the terminologies used to define the rock mass that is exposed to the
surface that is there is no covering soil in the surface with either herbs , shrubs or
any other natural coverings. Outcrop is a geological term referring to the
appearance of bedrock or superficial deposits exposed at the surface of the
Earth. In most places the bedrock or superficial deposits are covered by a mantle
of soil and vegetation and cannot be seen or examined closely. However in
places where the overlying cover is removed through erosion, the rock may be
exposed, or crop out. Such exposure will happen most frequently in areas where
erosion is rapid and exceeds the weathering rate such as on steep hillsides, river
banks, or tectonically active areas. Bedrock and superficial deposits may also be
exposed at the earth's surface due to human excavations such as quarrying and
building of transport routes.
6.2 Planar features at rock outcrops
The features preserved in rock, which are responsible to found the plane surface,
are called planner features. Bedding plane generally follow the deposition plane.

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6.2.a Bedding Plane
In geology a bed is the smallest division of a geologic formation or stratigraphic
rock series marked by well-defined divisional planes (bedding planes) separating
it from layers above and below. A bed is the smallest litho stratigraphic unit,
usually ranging in thickness from a centimeter to several meters and
distinguishable from beds above and below it. Beds can be differentiated in
various ways, including rock or mineral type and particle size. The term is
generally applied to sedimentary strata, but may also be used for volcanic flows
or ash layers.
In a quarry, a bedding is a term used for a structure occurring in granite and
similar massive rocks that allows them to split in well-defined planes horizontally
or parallel to the land surface.
6.2.b Foliation Plane
Foliation is usually formed by the preferred orientation of minerals within a rock.
Foliation is any penetrative planar fabric present in rocks. Foliation is common to
rocks affected by regional metamorphic compression typical of orogenic belts.
Rocks exhibiting foliation include the typical metamorphic rock sequence of slate,
phyllite, schist and gneiss.
Foliation in areas of shearing, and within the plane of thrust faults, can provide
information on the transport direction or sense of movement on the thrust or
shear. Generally, the acute intersection angle shows the direction of transport.
Foliations typically bend or curve into a shear, which provides the same
information, if it is of a scale which can be observed.
6.2.c Joints
In geology the term joint refers to a fracture in rock where there has been no
lateral movement in the plane of the fracture (up, down or sideways) of one side
relative to the other. This makes it distinct from a fault which is defined as a
fracture in rock where one side slides laterally past to the other. Joints normally
have a regular spacing related to either the mechanical properties of the
individual rock or the thickness of the layer involved. Joints generally occur as
sets, with each set consisting of joints sub-parallel to each other.
Joints form one of the most important types of discontinuity within rock masses,
typically having no residual strength.
6.3 Attitudes of geological structures
Strike and dip refer to the orientation or attitude of a geologic feature. The strike
of a stratum or planar feature is a line representing the intersection of that feature
with the horizontal. Strike and dip are determined in the field with a compass and
clinometer or combination known as a Brunton compass.
6.3.a Dip direction
It is the direction of the rock strata towards which it dips i.e. inclined and it always
lies at right angle to the strike. Strike is the direction on slopingsurface in which a
horizontal line can be drawn.

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6.3.b Dip amount
It is the maximum angle of inclination of the rock strata with the horizontal ,and is
measured in vertical plane.
6.4 Types of geological compass
Compass is used for the measurement of dip direction and dip amount of
bedding plane, folds, joints etc. there are five types of compasses in
general use.
 Simple compass
 Clinometers compass
 Brunton compass
 Clar compass
 Digital compass
6.5 Handling of geological compass
The compass used in the field was the Brunton Compass. Procedures to
handle the compass are as follows:
a. The compass should be opened carefully.
b. Measurement of the dip direction and dip angle should be done carefully.
c. Measurement of the dip direction and dip angle should be done as mention
above.
d. The rotation of the compass parts should be done carefully in such a way that
the minimum force is applied.
While using the compass for the accurate measurements, the compass should
be aligned in the direction of the maximum inclination.
6.5.1 Measurement of the Bearing (Dip Direction)
The face with the mirror should be placed parallel to the planar surface also aling
its maximum inclination. Then folding the other part, i.e. main part, the main, the
main part should be made horizontal by centering the spirit level in it, Then the
reading/bearing shown by the needle should be recorded as the dip direction of
the planar feature.
6.5.2 Measurement of Inclination (Dip Angle)
The edge of the compass should be aligned in the direction of maximum slope.
Then leveling the bubble in the center of the tube the angle of the structure was
seen, which is the dip angle. The leveling should be dine accurately. If necessary
the mirror can be used. For more accurate data, the reading can be taken at two
or more places in the same planar features.
6.5.3 Data measured using Brunton compass
The measurement of the planner features was done at the Bank of Malekhu
khola. The following readings were taken with the help of the Brunton Compass.
Readings for the dip amount and dip direction taken in the field:

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S.N. Dip Direction Dip Amount Attitude Remarks
1 172 86 86/172 BP
2 228 69 69/228 JP
3 90 16 16/90 JP
4 89 49 49/89 JP
5 256 61 61/256 JP
6 175 89 89/175 BP
7 90 25 25/90 JP
8 171 86 86/171 BP
16 176 86 86/176 BP
17 290 61 61/290 JP
18 122 75 75/122 JP
19 111 74 74/111 JP
20 167 89 89/167 BP
21 274 64 64/274 JP
22 95 36 36/95 JP
9 165 82 82/165 BP
10 154 74 74/154 BP
11 76 49 49/76 JP
12 174 84 84/174 BP
13 226 59 59/226 JP
14 71 26 26/49 JP
15 235 68 68/235 JP

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23 162 85 85/162 BP
24 132 76 76/132 JP
25 80 47 47/80 JP
Fig : Measuring of attitudes of bed rocks
7. STUDY OF GEOLOGICAL STRUCTURES
The structural features preserved in the rock during information of rock or after
formation of rock or after formation of rock is called geological structures, fold,
faults, joints etc are the examples of geological structures.
Continuous deformation structures: These are the products of plastic and
viscoplastic deformations e.g.: - folds, veins, foliation, cleavage etc
Discontinuous deformation structures: - These are the product of brittle
deformation e.g.: - joints, faults etc
7.1 Fold
Any type of undulations, bending and curvatures developed in the rocks due to
the action of stresses in the geological past and preserved in the rocks are
known as folds. Folds are the results of plastic and viscoplastic deformation in
the geological past preserved in the rocks. Folds are best displayed by stratified
formations such as sedimentary or volcanic rocks or their metamorphic
equivalents. But any layered or foliated rock, such as gabbro or granite, gneiss,
may show folds. Some folds are a few miles across. The width of other is to be
measured in feet or inches or even fractions of an inch. Folds of continental
proportions are hundreds of miles wide.
Fig: Fold
7.1.1 Recognition of fold in the field
i. The easiest and simplest way is the visual d: inspection. If we find any
geological structure according to the normal definition of a fold then it can be
identified as fold.
ii. The repetition & omission of beds also indicates the presence of fold.
iii. By plotting the attitudes of beds in map
iv. When the types of folds are to be recognized on the basis of the age
consideration of the beds, the top and bottom of beds are determined by taking
into account the nature, and form of the features occurring on the beds itself.
Accordingly some types of folds have been inferred.

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7.2 Fault
Faults are well- defined cracks along which the rock- masses on either side have
relative displacement along the fracture plane or they are the ruptures in which
the opposite blocks moved past each other. The displacement is parallel to the
fracture plane. The attitude of faults is defined in terms of their strike and dip. The
strike and dip of fault are measured in the same way as they are for bedding.
Fig: Fault
7.2.1 Recognition of fault in the field
To recognize the faults in the field, a number of criteria are used. The faults may
be directly seen in the field, particularly in artificial exposes such as river-cuttings,
road Cuttings, etc. In field the faults may be recognized as
i.Variation in the behaviour of the ground
ii.Evidences of the past deformation
iii.Change in bearing capacity of the materials
iv.Deviation in stress path
v.Variation in the hydraulic behaviour
7.2.2 Structure formed during faulting
i. Slicken sides: They are the polished and or striated or grooved
surfaces which are produced due to rubbing action
of the adjacent blocks during the act of faulting. These form important evidences
of faulting.
ii. Gouge: - It is a finely pulverized, clay-like powered rock material, which occurs
at or near the base of the faulting zones. It is obviously the result of strong
rubbing action on the rocks during the faulting process.
iii. Fault Breccia: - It is the crushed (and but powdered) angular, fragmentary
material produced during faulting and found in some cases at or mar the base of
the up thrown block. Very often the angular fragments get embedded and
cemented in the gouge and produce a rock-like mass once again which is also
called fault-breccia
iv. Mylonite: - This rock also called micro breccia, is extremely fine-grained and
very hare and coherent. Faulting is believed to be the cause of development of
such rocks. It is the metamorphic form of fault Breccia.
At chainage 330m upstream from Malekhu old bridge along left bank fault zone
was observed.
7.3 Joints
A joint is defined ,as a fracture in a rock between the sides of which there is no
observable relative movement . They are present in most consolidated rocks of
igneous , metamorphic and sedimentary origin.
7.3.1 Field identification of joints

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i. Joints are generally recognized in the field as faults without relative
displacement. Their dimension varies within wide –limits. Sometimes they are
very short in their extension, but in certain cases they are found to extend for
miles together.
ii. Joints commonly control the drainage pattern of an area. They also determine
the shape of coastlines, because they provide a passage, whereby water may
penetrate deeply into rock mass thus allowing weathering to take place.
iii. Jointed rocks are pervious to fluids and may act as aquifers or reservoir rocks
for oil or natural gas.
iv. Sometime joints act as avenues for molten rock materials to come above the
surface. It also determines the localization of some mineral deposits.
7.4 Thrust
A kind of reversed fault in which hanging wall has actually moved up relative to
the footwall is called trust.
e.g.: - Mahabharat thrust separates Nuwakot complex and Kathmandu complex.
7.5 Unconformity
Surface of erosional and depositional gap within a sequence of strata is called
unconformity.
These are usually the weak contact where the failure starts to generate. It
created permeability contrast thus natural springs or discharge can occur in such
places.
At Chainage 100m from suspension bridge above Trishuli river along Dhading
Besi old road unconformity was seen. Among series of rock strata soil and stone
deposition could be seen which established an unconformity at that place.
8. STUDY AND IDENTIFICATION OF ROCK IN THE FIELD ( along the
malekhu river and old Dhading Besi road )
8.1 Identification
Rocks are the aggregates of minerals, which form the earth's crust. So rocks are
composed of the minerals. According to the modes of origin, all rocks are
categorized into three major groups. They are: -
i. Igneous rocks or primary rocks
ii. Sedimentary rocks of secondary rocks
iii. Metamorphic rock
Rocks are identified in the field by the study of its size of grain or texture, shape
of grain layers, color, composition of minerals etc as they exposed naturally or
artificially on the surface of the earth.
8.2. Igneous Rock
These are the rocks formed by the solidification of magma either under neat the
surface or above it: accordingly they are divided into two groups:
a. Intrusive bodies: which are formed underneath the surface of the earth

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b. Extrusive bodies: which are formed due to consolidation of magma above
the surface of the earth. These are also known as volcanic rocks on the basis
of the depth of formation, intrusive rocks are of two type s:
tectonic rocks: which are formed at very depths.
Hypobysal rocks: which are formed at shallow depths.
8.2.1 Identification of Igneous Rock in the field
i. Generally igneous rocks are hard, massive, and compact with interlocking grains.
ii. Entire absence of fossils.
iii. Absence of bedding plane
iv. Random orientation of minerals
v.Usually contain much feldspar
Xenoliths: - The relic of the host rock preserved in the igneous rock is called
xenoliths.
8.3 Sedimentary Rock
Sedimentation rocks are formed by the process of sedimentation. Sedimentation
is the process by which the rocks are formed from the deposition and
consolidation of sediments or precipitation of soluble material s in layers .The
sediments are formed from the weathering of old rocks either igneous
metamorphic and even sedimentary itself and are then eroded and transported
by geological agents (water, wind, ice). These eroded and transported sediments
are then deposited on the depositional basic and accumulated layer by layer one
after another.
According to the modes of transportation of the deposits these rocks are sub -
divided into three types:
i. Mechanically deposited (clastic rock)
ii. Chemically and organically formed (non-clastic rock)
8.3.1 Identification of Sedimentary Rock in the field
i. Generally, soft, stratified i.e. characteristically bedded.
ii. Fossils common
iii. Statification, lamination, cross bedding. Ripple marks, mud-marks etc are the
usual structures.
iv. No effect on the enclosing or the top and bottom rocks.
v. Quartz, clay minerals, calcite, dolomite, hematite are the common minerals.
E.g.: - calcite, limestone, magnesite, sandstone, shale, etc.
8.4 Metamorphic Rock
These are formed by the alternation of pre-existing rocks by the action of
temperature, pressure added by sub-terrain fluids (magnetic or non magnetic).
8.4.1 Metamorphism
It is a natural process whereby the pre-existing rocks are altered or modified
under the influence of pressure, temp. & the chemical solution. Under the
influence of those factors, the rocks are changed into new rocks physically and
chemically .In metamorphic rocks minerals are arranged in preferred orientation.

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Types of metamorphism are:
i.Dynamic metamorphism
ii.Thermal metamorphism
iii.Dynamo thermal metamorphism
8.4.2 Identification of Metamorphic Rock in the field
i. Generally hard, interlocking grains and bedded (if derived from stratified rocks)
ii.Foliated, gneissose, schistose, granular lose, slaty etc are the common
structure.
iii. Fossils are rarely preserved in rocks of sedimentary origin except slate.
iv. Common minerals are andalusite, sillimanite, cyanite, cordierite, collastnite,
garnet, graphite etc.
E.g.: - slate, phyllite, schist, gneiss, amphibolites etc
a. Quartzite
It is usually light colored with shades of gray, yellow. It has medium specific
gravity (i.e. Sp.Gr. =7). It has quartz, as major constituents while others are mica,
feldspar. It is medium grained and the texture is massive and granular.
b. Slate
It is a black rock with low or medium specific gravity. Flaky minerals are quite
abundant and others are hard to distinguish. The rock is compact and can be
scratched by knife. It has foliation with slaty cleavage.
c. Marble
It is the rock of medium specific gravity, which is light colored. The major
component is calcite. Texture is massive and granular. A knife can scratch it.
d. Schist
It is the rock that has extremely variable color and specific gravity. The dominant
constituent is calcite. Others are mica, quartz and special minerals like muscovite
(white colored), biotite (black colored), and chlorite (green colored). The rock is
fusible and the property is called schistosity.
e. Gneiss
It is the rock with dark and light streaks or bands in alternating specific gravity are
variable. Garnet (like mustard seed) can be seen in the rocks. The grain is
medium or coarse. The structural feature is called gneissosity.
f. Phyllite
It is a greenish and soft type of rock. It is layered and foliation plane is quite
dominant with incompetent beds (the thickness less than 1cm is called foliation
other it is called bed). No distinct grains can be seen. It is an igneous rock that
has changed into metamorphic rock.
8.5 Discussion comment
According to the observations taken in the field, most of the rocks are
metamorphic in nature and sedimentary and igneous rocks in least. These are
the rocks that an engineer has to deal most with in the engineering practice. The
small sample tested in the laboratory cannot represent all the complex properties

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of the related rock. Even, if the rock has preserved the mentioned quality, it may
not be capable to resist the loads as we expected because of the conditions at
the site. So the strength, weathering condition, orientation and the spacing of the
joints and faults etc properties has to be studied in the detail to know completely
the property of the rock. These detail properties of the rocks can be known after
the field visit of the rock. Site for any engineering work has to b suggested only
after these detail studies of the rocks had been made. Hence field identification
of rock has greater importance in the field of civil engineering practice.
8.6 Major Rock type of the field area
During our study we found different rocks in our study area. The major rocks are
summarized as follows:
The metamorphic rocks found in the field are described below:
8.6.1 Slate
Slate is an extremely fine-grained metamorphic rock characterized by a slaty
cleavage, by virtue of which it can be split into thin sheets as roofing material.
Due to its low crushing strength it is also used as building material. It was found
at a distance of five hundred meter north of highway.
8.6.2 Phyllite
It is a medium to fine-grained metamorphic rock of complex silicate composition.
The rock shows a foliated structure and represents as intermediate stage the
presence of muscovite was found in the rock. This is found at the south from the
highway along the stream.Dark green type of phyllite was found in the Robang
Formation(RB).
8.6.3 Schist
Schist is megascopically crystalline metamorphic rock characterized by the
typical schistose structure. The constituent platy and flaky mineral and are
arranged in irregular parallel layers of bands.
8.6.4 Marble
Marble is essentially a granular rock composed chiefly of recrystallized calcite. It
is characterized by a granular structure. Marble often show banded structure.
Marbles are commonly used in building constructions in the form of blocks, slabs,
aches, and as chip for flooring. It is also used as decorative and ornamental
purpose. In Malekhu it was found at a distance of three thousand two hundred
seventy five meter south from the highway.
8.6.5 Gneiss
Gneiss is a megascopically crystalline metamorphic rock characterized by
segregation of constitute minerals into layers of bands contrasting color, textures
and composition. Feldspar and quartz are commonly in gneiss than in Schist.
Dark minerals of ampibole and pyroxene group are also common. The compact,
dense, massive varieties of gneiss are used in building and road metal.

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In Malekhu it was found at a distance of four thousand six hundred fifty meter
south from the highway. The gneiss was found in the boulder as an eye structure
and so called Augen Gneiss. This was found on the Kulekhani formation (ku) of
Bhimphedhi group.
8.6.6 Quartzite
Quartzite is granular metamorphic rocks composed chiefly of intercultural grains
of quartz. The name Orthoquartizile is used for a sedimentary rock of similar
composition but of different origin; it has siliceous cement. It contains sub-
ordinate amount of micas, feldspars, garnet and some amphiboles which result
from the impurities of the original sandstone during the process of
metamorphism. The rock is generally very hard, strong, dense and uniformly
grained. It finds extensive use in building and road construction.
Different types of SEDIMENTRY ROCKS found in the field of study are as
follows
8.6.7 Limestone
These are the most abundant sedimentary rock formed from the non-elastic
group and are composed of chiefly calcium carbonate. However the presence of
dolomite, quartz, feldspar and iron oxides is rather a common mineral. Limestone
is a primary source of materials for the manufacture of Portland cement and for a
wide variety of limes. Its other uses are in the Metallurgical industries as a flux.
It was found along the Prithvi Highway towards Gajuri as the Robang Formation
(RF) as a Malekhu Limestone Formation (ML) in the Upper Nuwakot Group.
8.6.8 Sandstone
Sandstone is a mechanically formed sedimentary rock. It is formed by the
cementation of the sand particles of sized between 1/10mm to 2mm in diameter.
Sandstone is perhaps the most familiar of all the rocks as it is usually quarried
and used more than any other rock, for all types of buildings. The various
varieties of sandstone are named after the cementing material. E.g. Siliceous
Sandstone, Ferruginous Sandstone, Calcareous Sandstone, Argillaceous
Sandstone etc.
8.6.9 Breccias
Breccias are a mechanically formed Sedimentary rock consisting of the angular
fragments. These sediments are heterogeneous in nature; cemented together by
clay; iron oxide, silica or calcium carbonate and are generally of more than 2 mm
size. Because of the heterogeneous character they are not used as building
stines but some of the varieties which are susceptible to polish can be used for
ornamental works.
Igneous Rocks found in the field of study are described below:
8.6.10 Granite
Granite may be defined as the Plutonic light colored igneous rock. These are
among the most common igneous rock. Two most common and essential mineral

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constitutes of granite are Quartz and Feldspar. The first is always recognized by
its vitreous luster, with MHN 7 and cleavage less wide translucent appearance.
Feldspar, forming Granite may be of two types: K-Feldspar, commonly
Orthoclase and the soda bearing Plagioclase Feldspar like Albite and Oligoclase.
Feldspar microcline may occur in some granite.
Agra Granite was found in the right bank of Malekhu Khola south west of
"Chhapan Danda".
The study of metamorphic rocks (now exposed at the Earth's surface following
erosion and uplift) provides us with very valuable information about the
temperatures and pressures that occur at great depths within the Earth's crust.
8.7 Major Rock Types of the Field Study Area
S.
N.
Physical Properties Sample 1 Sample 2
1. Colour Grey White
2. Texture Non Crystalline Crystalline
3. Structure/Cleavage Foliation, Slaty Bedding
4.
5.
Sp. Gr.
Acid Test/ Hammer
scratch Test
Low
_
High
React with Acid in the
powder form when sample is
scratched by the hammer
6. Mineral Composition Chloride, Mica, Clay Dolomite, Calcite
7. Rock type Metamorphic Sedimentary
8. Rock Name Slate Limestone(Dolomite)
9. Engg. Significance:
 Strength
 Drillability
 Blastibility
Low
High
Low
High
Low
High
10. Uses Roofing Construction Materials
11. Geological Formation Benighat Slate Malekhu Limestone

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S. N. Physical
Properties
Sample 3 Sample 4
1. Colour Greenish Grey White
2. Texture Non Crystalline Crystalline
3. Structure/Cleavag
e
Foliation, Slaty Random self interlock
4.
5.
Sp. Gr.
Acid
Test/ Hammer
Scratch Test
Low
-
High
-
6. Minerals Serisite+Slate Minerals Muscovite,biotite,
plagioclate quartz
7. Rock type Metamorphic Igneous
8. Rock Name Phyllite Granite
9. Engg.
Significance:
Strength
Drillability
Low
High
High
Low
Blastibility Low High
10. Uses Robang Formation Agra Granite
S.
N.
Physical
Properties
Sample 5 Sample 6
1. Colour Grey Grey
2. Texture Crystalline Crystalline

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3. Structure/
Cleavage
Foliation Foliation Gneissosity
4. Sp. Gr. High High
5. Minerals Quartz Feldspar, quartz, biotite,
muscovite
6. Rock type Metamorphic Metamorphic
7. Rock Name Quartzite Gneiss
8.
9.
10.
Engg.
Significance:
Strength
Drillability
Blastibility
Uses
Geological
Formation
High
Low
High
Construction Materials
Dunga quartzite
High
Low
High
Construction Materials,
aggregate, foundation material
Kalitar Formation
S. N. Physical
Properties
Sample 7 Sample 8
1. Colour White Grey
2. Texture Crystalline Crystalline
3. Structure/
Cleavage
Preferred Orientation of
mineral
Foliation, schistosity
4.
5.
Sp. Gr.
Acid Test/
Hammer
Scratch Test
Medium
Acid reacts vigorously
Sample is scratched by
hammer
Low
-
6. Minerals Calcite, silica, quartz, Chlorite, Clay, quartz,

17
muscovite, pyrite granite, mica granite
7. Rock type Metamorphic Metamorphic
8. Rock Name Marble Schist (garniteferrous)
9.
10.
11.
Engg.
Significance:
Strength
Drillability
Blastibility
Uses
Geological
formation
Medium to high
High
High
Flooring, construction
Material , raw materials for
cement if calcium carbonate
is more than 43%
Bhainse Dobhan marble
Low
High
Low
Construction of dry wall,
flooring
Raduwa Formation
9. STUDY OF RIVER CHANNEL MORPHOLOGY
River is a mass of water that flows along a path high to low gradient carrying
different materials and responsible for different geological actions,such as
erosion,transportation and dopositation of sediments.The route along which river
flows is called river valley.In engineering practice,many structures ,such as
dam,bridge ,reservoir etc. are constructed in the river channels. Besides
construction of infrastructures,construction materials are also barrowed from the
river territory.
9.1 Types of river channel
9.1.1 Straight River .
The river channel in which water is flowing in the same direction on straight path
is straight river channel. The prefect straight channel is rare and if present, the

18
length will not exceed ten times its width. The straight channel is formed in the
youth stage and at the head region of the river. The gradient of the river is high
causing the flow of velocity high.Since the energy level of such river is high .the
erosional rate is intensely higher than the deposition of the sediments.Deep
scouring along the river path is higher than the side cutting.straight rivers are
dominantly occurred in the Higher Himalayan region.
9.1.2 Braided River
In this type of river ,a single river path is diverted into several paths and may
converse to single later.the topography of the area is characterized by low relief.
The gradient of the river path is so low and the river area is widened and flow
with lower velocity.In the terai area the velocity of water in the river channel is low
and waters flows from different small channels. Since the energy level of such
river is low ,the deposition rate of sediments is intensly higher than the erosional
rateThick successions of sediments go on depositing along the river path and
river diverts to other subparts.
9.1.3 Meandering River
River channel in which course of river bends towards different directions within
small area is known as meandering river channel. This type of river flows along
zigzag path.The gradient of the river type is so moderate that the river strikes on
one end and return to other direction making zigzag path. The channel is
characterized by low velocity, soft rock type and is formed at the matured stage
of the river.
Meandering channel maintains a fairly steady width because erosion and
widening of the channel on one side is balanced by deposition and narrowing on
the other.
9.2 Land form develop by river channel morphologies
9.2.1 Oxbow Lakes
The individual loops of meandering stream in the advanced stage are separated
from each other that only by a narrow stripes of lands. During large water
discharging time the river has tendency to flow straight the stream starts flowing
in that particular region leaving the loop on one side as an isolated detached or
only slightly connected parts. These isolated curves or loop shaped part of the
meandering stream often contain some supplies of water when they are called
the ox-bo lakes. In case of meandering rivers, the streams detach loops and
charge their path across the shortest route. An oxbow is formed when neck of the
meander is reduced very much which is due to the low strength of the rock.
9.2.2 Pet Holes
These have various dimensions, shapes and are the depression, which are
excavated in the riverbeds by extensive erosion. These are formed in soft rock in
the cylindrical or bowl shaped. These are initiated by plucking out of pieces of
soft rocks from riverbeds due to the velocity of water abrasion and further
depressions.

19
9.2.3 River Valleys
In general, every large river forms its own valley. Valley is the low land
surrounded by hills of various slopes. The erosion processes due to the cutting
up of the bed form the valley.
9.2.4 Escarpment
Riverbanks might have alternate soft and hard rock layers. The soft rocks get
eroded quickly and the hard rocks get eroded later on. As the river continues
its flow, the bank falls suddenly creating a steep slope. This is known as
escarpment.
9.2.5 Fans
When rivers with low gradient enter the lower surfaces, the materials brought by
the river get accumulated. Also, the structure is not affected, as erosion doesn't
take place as water of the river flow over the structure.
9.2.6 Delta Deposition
The deltas are the triangular structures formed by the alluvial deposits at the
mouth of the river. Whenever a river with high gradient enters the standing water
source the river deposits some of the material brought by it. The continuous
deposition of material results in the formation of delta.
The number of river channels when meet at the point the flowing water looses
the velocity and therefore no other way then to drop down the balance of its load
right at this point of emergence at the mouth of the river known as the delta
deposition.
Fig: River terrace
9.3 River channel morphology at the Trishuli-Thopal Confluence
i. Erosion bank:
The bank of the river, which is weaker part, has the tendency to get eroded. This
is the unstable bank of the river.
ii. Deposition bank:
The bank on which deposition process takes place is called deposition bank.
iii. Channel bar:
The accumulation of the materials at the mouth of the river is called channel bar.
iv. Flood plane:
The plane or the area covered by the river when the river is in the flooding
condition. At these places, materials from very fine to coarser conditions are
found.
v. River terrace:
The area that the river used in the past to cover during flooding or normal
condition is called river terrace. This is the area has left the channel level to lower

20
level and the remnants of earlier deposits to form higher level. This area is very
suitable for human settlement. Gravel and sand is found in such places.
vi. Side bar or Point bar:
These are the remaining of deposits carried out by the river at the stage of higher
discharge. This is also known as side bar.
vii. Island:
It is the area formed by the river deposition. It is not necessary to be at its mouth.
Right bank of the Trishuli River at the height of sixty meter above the old road
from Malekhu to Dhading Besi three hundred meter upstream of suspension
bridge. Conference of Thopal Khola and Trishuli River.
10. ENGINEERING GEOLOGICAL DATA COLLECTION
Collection of engineering data from outcrops for certain purpose is called
engineering geological data collection. Engineering data are those, which are
purposed specific and quantitative. These data collected from outcrops are
attitude of rock (i.e. dip and strike).
10.1 Intact mass
Intact rock is the part of the rock mass which is free from the discontinuities. The
combination of the intact rock and the discontinues form the rock mass. Size of
the intact rock is small at the surface and large below the surface. It is different
from different types of the rock.
Intact rock strength:
It has already been explained that the intact rock is the rock material without
discontinuities. They have greater strength than the rock mass. Their strength
can be determined in the following ways:
 Check in lab: Required size of intact rock can be taken from the rock mass and
checked in the lab.
 Check by hammer striking: This is the cheapest and easiest way to find out the
approximate strength of rock material and this can be done directly in the
field. For this,
rock material is struck by geological hammer and the sound is identified. If
metallic sound comes then the rock material is strong having strength more than
100Mpa and if sound is as in soil then the rock material is weak having strength
less than 10Mpa. If sound is in between metallic to soil, then strength is also in
between 100Mpa to 10Mpa.
 Schmidt hammer: it is also an easy but nearly accurate method to check the
intact strength. it can give numerical value of strength of the rock
material.Actually the hammer is a special type of hammer which measures the
rebound value.
10.2 Rock Mass

21
The collective mass formed by the rock material ana discontinuities is called rock
mass. So the rock exposed on the outcrop is not rock,in fact it is the rock
mass.Rock materials (intact rock)is a part of rock mass. since in actual practice
discontinuties are present, rock material alone doesn't exists in nature.
10.3 Parameters of Engineering Geological Data
10.3.1 Rock type
The rock are classified on the basis of the characteristics of intact rock as well as
the discontinuities present.
 Cleavage/foliation plane ,bedding plane
 Materials
 Particle size textures etc.

10.3.2 Orientation
Orientation of discontinuities is the attitude of the discontinuities. Depending
upon the slope of discontinuity rock has different strength at the different
direction .If the direction of the discontinuity is in the same direction as the rock
mass ,it is an unfavorable condition. But if the discontinuity is in opposite
direction to the rock mass,it is a favorable condition.
10.3.3 rock strength
The strength of the intact rock is tested by Schmitt Hammer rebound test.
Schmitt Hammer is the instrument used to test bearing capacity of site rock mass
by rebound test. There are two ways of testing by Schmitt Hammer,one is uni-
axial and another is tri-axial test.
10.3.4 Spacing
It is the perpendicular distance between the two adjacent discontinuities of the
same set.The space between the discontinuities set in the same direction also
causes variation in the strength of the rock.The rock material in between the
discontinuity is intact material .The volume of intact material governs the strength
of the rock.
10.3.5 Aperture
Aperture is the open spacing present in the rock due to discontinuity present in it
.The crack due to any means like alkaline water has high tendency to dissolve
calcite material may get widened up Depending upon space it is classified as
widely open (>1 cm),open (2 mm-1 cm),close (<2mm),tight (<1mm).The
apertures wide and open cause the mechanical discontinuity as no stress is
transferred all over the the rock. However if the open discontinuity is filled with
any other material then strength is transferred. The open and close aperture if is
filled by any other material then the strength and the stability of the rock
increases depending upon the material type filling the aperture.
10.3.6 Roughness

22
It is one of the characteristics of the discontinuity present in it. In rough
discontinuity surfaces due to low friction shear strength is high. It is generally of
two types rough planar(rough surface with a plane flow) rough wavy (rough
surface with a wave like flow).
10.3.7 Seepage
It is the flow of water under gravitational forces in a permeable medium.
Flow of water takes place from point of high head to a point of low head.
11. CONCLUSIVE REMARKS
Once heard thing may be forgotten but once VISITED thing never forgotten. This
main purpose of field trip conducted by AITM. Minimum knowledge require for
engineers in geology field is fulfilled in this trip.
The subject GEOLOGY is really one of the most important subjects for CIVIL
ENGINEER. The three day tour on MALEKHU area has proved as a chance to
learn the various geological resources of the site,geological events,geological
conditions, and the related area to the engineering point of view .The study was
related to the practical as well as theoretical. In this tour, we saw and felt the
major type of rocks in their natural condition and pictured them. The visit has
yielded rich knowledge and the information about the morphology of the
MALEKHU river which merges with the TRISULI river. It has also yielded good
knowledge and information about the landslides and their impact on the local and
national economy. The use of geological compass to find the attitude of a rock.
Finally it will be better to say that if there had not been any geological trip,we
would not have learnt a lot of these information as theoretical knowledge is not
enough for field work. So this geological helped a lot us for study and later on
during field works.

Geology report by jitu

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