A report on field visit to Malekhu Preface Nepal is a land of geological diversities. So the knowledge of engineering geology is very essential for the engineering structures to be stable and durable in this region. To provide the students, the basic concept of engineering geology and geological structures, the Malekhu field visit was extremely necessary because the students themselves can see everything in front of them, they can measure themselves various geological parameters and analyze the various geological structures such as folds, faults, unconformity etc. This report provides the gist of the Malekhu field visit. Every activity performed, every data taken, every site visited and every difficulty faced and each and every results of such site visit are orderly maintained in this report. The sketches of each and every site along with their photographs, the location of the site (in terms of chianage), the observations made and the findings of the site including the techniques used, the description of the geologically vulnerable zones, their causes, engineering significance and ways of control make this report very visual and gives the readers a clear ideas about the visit.
Transcript
A report on field visit to Malekhu
PrefaceNepal is a land of geological diversities. So the
knowledge of engineering geology is very essentialfor the engineering structures to be stable anddurable in this region. To provide the students, thebasic concept of engineering geology and geologicalstructures, the Malekhu field visit was extremelynecessary because the students themselves can seeeverything in front of them, they can measurethemselves various geological parameters and analyzethe various geological structures such as folds,faults, unconformity etc.
This report provides the gist of the Malekhu fieldvisit. Every activity performed, every data taken,every site visited and every difficulty faced andeach and every results of such site visit are orderlymaintained in this report. The sketches of each andevery site along with their photographs, the locationof the site (in terms of chianage), the observationsmade and the findings of the site including thetechniques used, the description of the geologicallyvulnerable zones, their causes, engineeringsignificance and ways of control make this reportvery visual and gives the readers a clear ideas aboutthe visit.
A report on field visit to Malekhu
Acknowledgement
We would like to express our deep and sinceregratitude to the Department of Civil Engineering,Pulchowk Campus and especially to the section ofGeology. Special vote of thanks goes to theinstructors during the field visit, namely Prakashsir, Basant sir, Hitendra sir and Shrawan sir,without which the field visit would have beenimpossible. They shall be ever credited for the indepth knowledge of the geology which otherwise wouldnot have gained!
Also, we are thankful to all the persons who arecontributed so immemorable, knowledgeable andentertaining. All of the friends who were always withus in the field are thanked for making the fieldvisit a worth time to have and worth place to be.
Of course, on the course of our stay, ChitwanTriveni Hotel and its owner helped us in every way tomake our stay comfortable, to whom we acknowledge.All others directly or indirectly helping us to makeour field visit successful are thanked.
All the references which helped in making ourreport meaningful and knowledgeable are thanked. Alsoa special vote of thanks goes to Microsoft Companyand Bill Gates for making this wonderful MicrosoftWord without which report would not have beenpossible.
A report on field visit to Malekhu
Last but not the least, group E thanks themanufacturer of laptop and desktop on which thisreport is prepared!
-Group”E”
A report on field visit to Malekhu
IntroductionGeology and civil engineering shared a close and
intimate relation with each other as no foundationcan be laid in air, every civil engineeringstructures stands on earth’s surface and thereforeit’s vita to know about the earth’s surface, variouslandforms and factors affecting it which coincideswith literal meaning of geology.
The present era is the era of construction, socivil engineering today not only deals withconstruction of structures(buildings, dams, bridgesetc) rather it deals with construction of structureswith maximum safety lesser efforts in a shorter timeat a minimum possible price.
For all these factors, we need to know a lot aboutthe existing geological condition. In theconstruction site, we need to know about the types ofsoil and it’s properties so that we could modify,excavate or replace it as required. We need to knowabout the rock underlying it, exposed at the site. Weneed to know about the ground water condition, weneed to know about the mass movement and mostimportantly we need to know about the faults, foldsand fractures present at the site. For all theseinformation, we could go nowhere but study geology.So geology plays a vital role in civil engineering.
As we have already discussed the importance ofgeological knowledge, only theoretical knowledge islame when we are concerned with civil engineeringwhich is total practical.
It’s very difficult for us to understand thevarious geological features such as beds, bedding
A report on field visit to Malekhu
plane, their orientation, strike, faults, folds,fractures, and river morphology but it will becomevery effective when we see all of them in front ofour eyes. In the beginning phase, when we are justbuilding our geological knowledge, our basic conceptmust be very clear for which geological field visitor trip is essentially required.
In a way, this reports provides us both the abovementioned aspects are clarified. The readers willhave knowledge of various geological features andtheir civil engineering significance through thisreport.
A report on field visit to Malekhu
LocationMalekhu lies on lesser Himalayan region of Nepal.
It has peculiar geological features within a smallrange of area. The Malekhu V.D.C. of Dhading districtlies about 70 kms south west of Kathmandu valley andis located at latitude of 27o 50' 38'' to 27o 45' 50''and longitude of 24o 49' 5'' to 84o 50' 50’’. It issituated on the bank of Trishuli and Malekhu River.The Trishuli River is running from the easterndirection to the western direction and the MalekhuRiver from south to north which mingles into theTrishuli River. Also, the Malekhu River has atributary namely the Apakhola which meets the MalekhuRiver at a distance about 3 kms from the Malekhubazaar. Climatically Malekhu is a sub-tropical zone.Mainly the rainfall is during the monsoon.
Objectives of field study To be clear enough about joints, faults and
folds.
To estimate, where the bridge site should be
selected?
To identify the rock type and its property.
To measure strike of bedding plane.
To measure the dip direction and dip amount
of the bedding planes and joints
A report on field visit to Malekhu
To study about the rock mass and its
classification on the field.
To study the mass movement.
To understand the River morphology
Methodology
The primary method of collection of data was usedin the field during the field visit to Malekhu. Thevisit was a very useful tool to help develop aconcept about the geological structures, massmovement, rock mass analysis and rating.
The primary methods used are:
Sighting of the field Sketching of the field in its natural
condition Photograph of the field Collection of data Interpretation and analysis of data
A report on field visit to Malekhu
Study of Slope instabilities along road corridor
Mass movement
Mass movement is the detachment of and down slopetransport of soil and rock material under theinfluence of gravity and accelerated by variousfactors especially water. The sliding and flowing ofthe materials takes place due to their position andgravitational forces but the mass movement isaccelerated mainly by the presence of water. The maincause of mass movement is the gravitational force. Aswhen gravitational force acting on a slope exceedsits resisting force, slope failure (mass wasting)occurs. But various factors like strength, folding,faulting, jointing, foliation, bedding, soil depth,porosity, permeability, rock type and soil type playeffective role in mass movement.
Types of mass movement
Depending upon mechanism, types of material andrate of movement mass movement can be classified intomainly three types viz. soil failure, landslide anddebris flow. They can be briefly defined as follows:
A report on field visit to Malekhu
Landslides Descent of a mass of earth and rock down a
mountain slope is often known as landslide.Landslides may occur when water from rain and meltingsnow sinks through the earth on top of a slope, seepsthrough cracks and pore spaces in underlyingsandstone, and encounters a layer of slipperymaterial, such as shale or clay, inclined toward thevalley. The water collects along the upper surface ofthis layer which it softens. If the support issufficiently weakened, a mass of earth and rockslides down along the well-lubricated layer. Somegreat landslide masses move slowly and spasmodicallyfor years, causing little destruction.
There are various types of landslides dependingupon movements and materials. They are:
a. Fallsb. Topplesc. Slidesd. Spreadse. Flows
Debris flowA debris flow is a fast moving, liquefied
landslide of unconsolidated, saturated debris that
A report on field visit to Malekhu
looks like flowing concrete. It is differentiatedfrom a mudflow in terms of the viscosity and texturalproperties of the flow. Flows can carry materialranging in size from clay to boulders, and maycontain a large amount of woody debris such as logsand tree stumps. Flows can be triggered by intenserainfall, glacial melt, or a combination of the two.Speed of debris flows can vary from 5 km/h to up to80 km/hr in extreme cases. Volumes of materialdelivered by single events vary from less than 100 tomore than 100,000 cubic meters. Variables consideredimportant in debris flow initiation include slopeangle, available loose sediment, and degree of landdisturbance by activities such as forest harvesting.
Slope failureSlope failure is the movement of weathered surface
soil layer/rock of steep slope in small dimension andrapid movement. In this there may be absence of slipsurface. These types of failures occur due to steepslopes, loose soil, and excavation of rock or soil ondownhill side. There are two kind of slope failure.There are two kind of slope failure. They are (a).Slope failure (b).Rock failure
The preventive measures for the mass movement are:-
1. Retaining structures: These are the walls arerigid walls which are used to support the soil masslaterally so that the soil can be retained atdifferent levels on the two sides. Following are the
A report on field visit to Malekhu
type of retaining walls constructed on risky zonesfor mass movement prevention:-2. Gabion wall: Those wall are made by filling thestones in the wire net. Those wall check the soilmaterial without undergoing failure due to theirflexibility.3. Stone masonry wall: Those walls are made byjoining stones with the cement concrete.4. Concrete masonry wall: Those walls are made bymixtures of aggregates of cement.These structuresare only suitable to prevent small scale of massmovements (mostly landslides).5. Rock anchoring: In this method an anchorwhich is made steel bar or wire is anchored to thesliding soil mass to the bed rock. However the bondstrength between anchor and rock at the anchor partshould be considered beforehand in this method.6. Pile works: In this method sheet pile off200-600 mm are driven through the sliding surfaceto control landslide movement directly. This methodis employed for urgent and important locations. Theyare installed from the center to the lower part ofthe landslide block.
Description of mass movement in each locationLocation A(chainage 17+00 km, along Trivhuvan highway)
A typical type of mass movement was observed alongthe Tribhuvan highway at 17 km chainage.A landslidewas seen which showed different features. Some debrisflow as well as the slope failure was also seen.
A report on field visit to Malekhu
The factors causing these may be: a. Stress developed by vehicles and road
construction.
b. Due to reduced strength of soil caused byvarious other geological factors and violentrainfall.
Measures for remediation: 1. Both gabion wall and the concrete masonry
wall at the side of highway. Crib wall and the checkdam were also seen.
2. Rock anchoring was observed was observed about100 m ahead which were preventing the movement ofsliding mass.
SKETCH AND PHOTOGRAPH
Figure 1: Location A
A report on field visit to Malekhu
Location B(Belkhu khola bridge along Prithivi Highway)
Another location to be observed was Belkhu KholaBridge. This location had a bridge which was a newone. However we could clearly see some reminisces(pillars, old bridge parts) at the sides of existingbridge. Actually what happened was that the oldbridge span was swept away by the flood in 2050 B.S.This was due to the fact that the bridge span waskept below peak flood level. However the existingbridge span is kept above the peak flood level.
From the study, we came to know that the peakflood level should be studied before making thebridges and such structures near the rivers.
The main thing to be studied however was theoutcrop which was observed at the right bank ofTrishuli River. Amazing thing was that the slope wasvertical but stable. Many things contribute to makethe slope stable, such as there were vegetations inthe upper layer of the slope. The shear stress wasbalanced in the region, thus stabilizing the slope.
τ=σtan∅+c
where,τ=shearstress
σ=normalstress
∅=frictionangle
c=cohesion.
A report on field visit to Malekhu
Hence, it was interpreted that the normal stress,friction angle and the cohesion are high in theslope.
SKETCH AND PHOTOGRAPH
Figure 2: Location B
Location C (chainage 42 km along Prithivi Highway) A complex landslide was observed in this area.
There were different ways implemented in the area toavoid further landslide.
A report on field visit to Malekhu
The remedies used in this area are:
1. Cascade drainage for surface drainage.2. Gabion wall for stabilizing continuous moving
mass.3. Stone machinery wall for stabilizing the fixed
mass in the bed rock with weep hole and sub-surfacedrainage system.
4. Technique of bio-engineering used for whichsome special types of plants like sishau, kaher,bakiyino,bhojetro are planted in a proper way.
Sketch and photograph
Figure 3:Location C
A report on field visit to Malekhu
Location D(chainage 43 km along Prithivi Highway)Rock slope failure was observed at the chainage of
43 km along the Prithivi highway from Kathmandu. Plane, wedge and toppling failure observed in that
area. A colluvial fan was also observed on the slope.The slope was however seemed to be temporarilystabilized.
Failure mechanisms on rock slope: There are three failure mechanisms on rock slope on
the basis of orientations of discontinuities withrespect to the orientations of hill slope.
Plane failureWhen the dip direction of planner features such as
joints, beddings or foliations is at the same direction(±20◦) as that of the hill slope or cut slope then plainfailure is possible. However friction angle has alsoinfluence in this mechanism.
Wedge failureWhen two planes intersects obliquely across the
slope face and their line of intersection plunges atthe same direction as the dip direction of hill slopeor cut slope then wedge failure is possible.
Toppling failureThe toppling failure is possible when the planar
features dip opposite to hill slope or cut slope andthe hill slope or cut slope is steep enough than theplanner features.The main causes for such failures inthe location might be due to improper cutting of rockbed during the road construction.
A report on field visit to Malekhu
The preventive measured used in this location are: a. Gabion walls are placed near the road as check
wall and catch wall.However, the slope has self- stabilized.
Figure 4: Location D
A report on field visit to Malekhu
Measurement of attitude of rock bed
Compass
Compass refers to the device used for measurementof angles. In geology, a magnetic compass is used to find out the attitude of bed, i.e. the dip amount anddip direction.
Types of compasses
Clinometers compass
The compass which can measure bearing andorientation with two sets is calledclinometers compass. Since it doesn’t consistthe sprit level, it should be leveled byapproximation and may not be accurate.
A report on field visit to Malekhu
Brunton compass:
It consists of sprit level and can measurebearing and inclination with relatively lesserror.
Clar compass:
It can read both inclination and bearing atsimultaneously. It is relatively easier tohandle.
Digital compass:
The value of the bearing taken are directlydisplayed as digits so it is very simple tooperate.
Digital PC compass:
This is similar to digital compass. Inaddition to it, this compass is directlyconnected to the computer so there is no needto observe the data and to note down it in thenote book. The taken data are directlytransferred to the computer.
A report on field visit to Malekhu
Handling of geological compass:
A geological compass is used to measure theattitudes of the geological features (strikeand dip) and orientation of the slopes. In thepast, the compass was mainly used formeasuring the bearing of object with respectto north and to measure inclination. The mainoperation of geological compass consists ofopening the compass carefully, leveling thespirit level and placing the compass on theplaner feature for measurement.
Planar features and attitude of planar features
The planar features of rock consists of rock beds, joint plane and foliation planes. The orientation of rock beds can be described from the attitude. Attitude is the three dimension orientationof planar features of rock. Attitude of beds or jointplane can be described from strike and dip.
StrikeStrike is the line formed by intersection of an
inclined geological plane and its own projected horizontal plane.
A report on field visit to Malekhu
Dip amount and directionDip amount is the angle between geological plane
and horizontal plane which provides inclination of the bed.
And dip direction refers to the direction of the horizontal projection of the bed. Strike and dip direction are perpendicular to each other.
Measurements of attitudes of the rocks
Location No.L1:
About 50m far from the old (broken) bridge along Prithivi Highway the data of rock strata are taken.
S.N. Dip Direction Dip Amount Attitude Plane
Remarks
Observed by : Sujit Bhandari
1 S 82O E 30O S 82O E/30O J.P
2 S 75O W 10O S 75O W/10O J.P J.P=Joint Plane3 S 78O E 21O S 78O E/21O J.P
4 S 04O E 86O S 04OE/86O B.P
5 S 21O E 71O S 21O E/71O B.P B.P=Bedding Plane6 S 70O W 50O S 70O W/50O B.P
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7 N 56O W 84O N 56O W/84O B.P
8 S 09O E 86O S 09O E/86O B.P
9 S 83O W 61O S 83O W/61O J.P
10 S 87O W 63O S 87O W/63O J.P
Observed by : Sudeep Paudel
1 S 88O E 31O S 88O E/31O J.P
2 S 64O W 50O S 64O W/50O J.P
3 S 04O E 87O S 04O E/87O B.P
4 N 55O W 45O N 55O W/45O B.P
5 N 56O W 64O N 56O W/64O J.P
6 S 81O W 85O S 81O W/85O J.P
7 S 20O E 85O S 20O E/85O B.P
8 N 78O E 21O N 78O E/21O B.P
9 S 14O E 82O S 14O E/82O J.P
10 N 19O E 84O N 19O E/84O B.P
Observed By : Simpson Lamichhane
1 S 18O E 84O S 18O E/84O B.P
2 S 20O E 85O S 20O E/85O B.P
3 S 12O E 87O S 12OE /87O B.P
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4 S 14O E 82O S 14O E/82O B.P J.P=Joint Plane5 S 20O E 84O S 20O E/84O B.P
6 S 11O E 83O S 11O E/83O B.P B.P=Bedding Plane7 S 18O E 90O S 18O E/90O J.P
8 S 16O E 78O S 16O E/78O B.P
9 N 85O E 10O N 85O E/10O J.P
10 N 89O W 36O N 89O W/36O J.P
Observed By : Tshreya Bhattarai
1 N 84O W 47O N 84O W/47O J.P
2 S 16O E 78O S 16O E/78O B.P
3 N 56O E 76O N 56O E/76O B.P
4 S 82O W 64O S 82O W/64O B.P
5 S 18O W 90O S 18O W/90O J.P
6 N 19O E 84O N 19O E/84O J.P
7 S 17O E 87O S 17O E/87O B.P
8 S 11O E 86O S 11O E/86O B.P
9 N 56O E 84O N 56O E/84O B.P
10 N 60O W 79O N 60O W/79O B.P
Observed by : Sudip Thapa
A report on field visit to Malekhu
1 S 14O E 89O S 14O E/89O B.P
2 S 75O W 52O S 75O W/52O J.P
3 N 89O W 36O N 85O W/36O J.P
4 S 19O E 75O S 19O E/75O B.P
5 N 86O W 52O N 86O W/52O J.P
6 N 85O E 10O N 85O E/10O J.P
7 S 85O W 86O S 85O W/86O J.P
8 S 04O W 84O S 04O W/84O B.P
9 S 68O W 67O S 68O W/67O J.P
10 N 89O W 58O N 89OW/58O J.P
Observed by : Sudesh Dahal
1 N 55O W 79O N 55O W/75 J.P
2 S 69O W 66O S 69O W/66 J.P
3 N 20O W 79O N 20O W/79 B.P
4 S 11O W 83O S 11O W/83 B.P
5 N 85O W 10O N 85O W/10 J.P
6 N 00O W 54O N 00O W/54 J.P
7 S 20O E 85O S 20O E/85 B.P
8 N 78O E 21O N 78O E/21 J.P
9 N 02O E 88O N 02O E/88 B.P
A report on field visit to Malekhu
10 N 20O W 59O N 20O W/59 J.P
STUDY OF GEO-STRUCTURES
Structure geology deals with the mechanism andtypes of deformation of rock or earth’s crust due todistribution of stress generated through variousgeological processes. Structural geologists usemicroscopic analysis of oriented thin sections ofgeologic samples to observe the fabric within therocks which gives information about strain within thecrystal structure of the rocks. They also plot andcombine measurements of geological structures inorder to better understand the orientations of faultsand folds in order to reconstruct the history of rockdeformation in the area. In addition, they performanalog and numerical experiments of rock deformationin large and small settings.
Compressive, tensile and shear stress producestrain in the structures in the earth’s surface. Thedeformation may be elastic, brittle, ductile; whichdetermines which structure is to be formed. Thestructures may be of following types :
The term fold is used ingeology when one or a stack oforiginally flat and planarsurfaces, such as sedimentarystrata, are bent or curved as aresult of plastic (that is,permanent) deformation. Fold is the ductiledeformation caused due to compressive stress. Foldmost often occurs well inside the earth’s surface.
Anticline: linear, strata normally dip away fromaxial center, oldest strata in center.
Syncline: linear, strata normally dip towardaxial center, youngest strata in center.
Symmetrical: limbs form mirror image of eachother, both limbs dip at equal angle in oppositedirection, axial plane is veritcal.
Unsymmetrical: limbs donot form mirror image ofeach other, both limbs dip at unequal angle inopposite direction, axial plane is oblique.
Engineering Significance:
1. For the foundation of dam in a large fold,upstream is more favourable than the downstream.
2. In fold, there is more stress in the zone ofhinge line than the other zones.
3. In synclinal aquifer, the underground waterpotential is higher and is adverse in case ofanticlinal fold.
LOCATION
L6,
FIELD OBSERVATIONS
An anticline asymmetric fold was seen in the site.The existence of fold was confirmed by the sightingof hinge line and the different dipping of the rockin the boulder seen. Also, fold in the area wasconfirmed by the dipping of the rock masses ondifferent directions from the location.
A fault isa planarfracture ordiscontinuityin a volume ofrock, acrosswhich therehas beensignificantdisplacementin the planeparallel to thefracture plane. Fault is the result of brittledeformation due to tension, compression and shearstress. Large faults within the Earth's crust resultfrom the action of tectonic forces. Energy releaseassociated with rapid movement on active faults isthe cause of most earthquakes.
A fault line is the surface trace of a fault, theline of intersection between the fault plane and theEarth's surface.Since faults do not usually consistof a single, clean fracture, geologists use the termfault zone when referring to the zone of complexdeformation associated with the fault plane.The twosides of a non-vertical fault are known as thehanging wall and footwall. By definition, the hangingwall occurs above the fault and the footwall occursbelow the fault.
LOCATIONL7, located at a distance of 200 m from old
bridge on the left bank of Malekhu River.
FIELD OBSERVATIONSSmall scale fault was seen in the site. The
evidence of the fault was that of the presence ofpowder gauge and breccia. Due to high heat andtemperature, the gauge was seen along with thebreccia, which provides the direct evidence of theexistence of the fault.
A report on field visit to Malekhu
SKETCH AND PHOTOGRAPH
Figure 10: Fault as seen in the field
THRUST
A thrust is a type of fault, or break in theEarth's crust across which there has been relativemovement, in which rocks of lower stratigraphicposition are pushed up and over higher strata. Theyare often recognized because they place older rocks
above younger. Thrust faults are the result ofcompression forces.
Thrust faults typically have low dip angles. Ahigh-angle thrust fault is called a reverse fault.The difference between a thrust fault and a reversefault is in their influence. A reverse fault occursprimarily across lithological units whereas a thrustusually occurs within or at a low angle tolithological units. It is often hard to recognizethrusts because their deformation and dislocation canbe difficult to detect when they occur within thesame rocks without appreciable offset of lithologicalcontacts.
If the angle of the fault plane is low (generallyless than 20 degrees from the horizontal) and thedisplacement of the overlying block is large (oftenin the kilometer range) the fault is called anoverthrust. Erosion can remove part of the overlyingblock, creating a fenster (or window) when theunderlying block is only exposed in a relativelysmall area. When erosion removes most of theoverlying block, leaving only island-like remnantsresting on the lower block, the remnants are calledklippen (singular klippe).
Engineering Significance:
The engineering significance of a thrust is sameas that of a fault but a thrust extends over a largerzone and is more likely for re-occurrence due to itslow angle. Even some thrusts keep on being activewith very small velocities. Thus it should be taken
in care before designing any civil engineeringstructures.
FIELD OBSERVATIONS:
The Malekhu region also contains the Main CentralThrust (MCT), also known as Mahabharat thrustextending throughout the Mahabharat range. Theevidence of the thrust has been laid by sighting themetamorphic rocks on the earth’s surface along withthe younger rock types on the surface. The youngingsequence has been reversed in the region givingindirect evidence of thrust.
An inverted metamorphic field gradient associatedwith a crustal-scale south-vergent thrust fault, theMain Central Thrust, has been recognized along theHimalaya for over 100 years. A major problem inHimalayan structural geology is that recent workershave mapped the Main Central Thrust within the GreaterHimalayan Sequence high-grade metamorphic sequencealong several different structural levels.
A report on field visit to Malekhu
PHOTOGRAPH
Metamorphic rocks
Figure 11: Evidence for the thrust
Sedimentary rocks
A report on field visit to Malekhu
JOINT
The term joint refers to a fracture in rock wherethere has been no movement in the plane parallel tothe plane of fracture of one side relative to theother. This makes it different from a fault which isdefined as a fracture in rock where one side slideslaterally past the other. However, there could be aperpendicular displacement to the plane of fracture.Joints normally have a regular spacing related toeither the mechanical properties of the individualrock or the thickness of the layer involved. Jointsgenerally occur as sets, with each set consisting ofjoints sub-parallel to each other.
Joints are classified based on the attitude ofjoint w.r.t. the attitude of the bedding and on thebasis of the orientation of joint sets.
Geometric classification Dip joint: strike of a joint parallel to the dip of bedding.
Strike joint: strike of a joint is parallel to the strike of the bedding.
Oblique joint: strike of a joint makes an angle with the strike of the bedding.
Genetic classification: Mural joints: joints on the massive igneous rocks, three sets of joints perpendicular to each other
Columnar joints: joints formed on volcanic igneous rocks such as basalts, vertical prominent planes breaking the rocks into hexagonal prismatic columns
Sheet joints: one set of prominent joints found in massive igneous rocks
Tension joints: joints developed due to tensile forces acting on the rock, found commonly on the
A report on field visit to Malekhu
PHOTOGRAPH
Figure 12: Joints
ENGINEERING SIGNIFICANCE
1.The joints represent the areas where the rockmass has been fractured. So, the rock mass maydetach at the point and are unnecessary inlight of the engineering construction.
2.The reservoirs, tunnels and dams should not beconstructed in these regions as there arechances of water leakage.
3.There are chances of ground water seepage inthe areas of joints.
4.As the areas of joints are the regions ofbreakage, the site is weak and heavyconstructions such as dams, high raise
A report on field visit to Malekhu
buildings, etc. shall not be constructed inthese areas.
Joint planes are more harmful than the faultplanes but less harmful than the bedding planes.However, the attitude of the joint planes havegreater significance in the construction within thesepalces.
UNCONFORMITY
An unconformity is a buried erosion surfaceseparating two rock masses or strata of differentages, indicating that sediment deposition was notcontinuous. In general, the older layer was exposedto erosion for an interval of time before depositionof the younger, but the term is used to describe anybreak in the sedimentary geologic record.
The rocks above an unconformity are younger thanthe rocks beneath (unless the sequence has beenoverturned). An unconformity represents time duringwhich no sediments were preserved in a region. Thelocal record for that time interval is missing andgeologists must use other clues to discover that partof the geologic history of that area. The interval ofgeologic time not represented is called a hiatus.
The formation of unconfirmity may be attributed tothree main processes like erosion, deposition andtectonic activities. Its development involves thefollowing stages:
1. The formation of the older rocks.2. Upliftment and surfacial erosion of the older
rock.3. Again, the formation of younger succession of
beds after long interval above the surface oferosion.
There are three types of unconformity:
Parallel Unconfirmity
Parallel unconformity is atype of unconformity in whichstrata are parallel; there islittle apparent erosion and theunconformity surface resembles asimple bedding plane. It is alsoknown as disconfirmity,nondepositional unconformity or pseudoconformity.
Angular unconfirmityAngular unconformity is an
unconformity where horizontallyparallel strata of sedimentaryrock are deposited on tilted anderoded layers, producing anangular discordance with theoverlying horizontal layers. Thewhole sequence may later bedeformed and tilted by further orogenic activity.
metamorphic or igneous rocks when the sedimentaryrock lies above and was deposited on the pre-existingand eroded metamorphic or igneous rock. Namely, ifthe rock below the break is igneous or has lost itsbedding by metamorphism, the plane of juncture is anonconformity.
LOCATIONL3,
FIELD OBSERVATIONSUnconformity was seen and identified in the field.
An unconformity existed between the bed rock and thedepositional layer. The deposited layer was loose andconsisted of small stone particles and sand,deposited over an intact bed rock, exposed at thatplace. The difference in the depositional time periodwas clearly seen which confirms the presence ofunconformity.
Rock is defined as naturally forming, hard andcompact solid aggregates or assemblage of minerals
Figure 16: Unconformity (Loose soil in the left and bed rock on the right)
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forming crust of the earth. The branch of geologythat deals with the study of various aspects of therocks, such as their mode of formation, compositionand occurrence is called petrology.
The rocks are classified as following on thebasis of their mode of formation:
A. Igneous Rock The rocks formed by
the cooling andsolidification of moltenmobile mineral called‘magma’ by thecrystallization arecalled igneous rock. Theprocess of formation ofigneous rock is calledmagmatism.
Igneous rocksare formed when moltenmagma cools and are divided into two main categories:plutonic rock and volcanic. Plutonic or intrusiverocks result when magma cools and crystallizes slowlywithin the Earth's crust(example granite), whilevolcanic or extrusive rocks result from magmareaching the surface either as lava or fragmentalejecta (examples: pumice and basalt) .[1]
the process ofaccumulation,compaction,cementation, andconsolidation of thesediments are calledsedimentary rock. Thesediments are formed bythe weathering of oldrocks, igneous,metamorphic and evensedimentary.
Sedimentary rocks are formed by deposition ofeither clastic sediments, organic matter, or chemicalprecipitates(evaporites), followedby compaction of the particulate matter andcementation during diagenesis. Sedimentary rocks format or near the Earth's surface. Mud rocks comprise65% (mudstone, shale and siltstone); sandstones 20 to25% and carbonate rocks 10 to 15% (limestone anddolostone).[1]
C. Metamorphic Rock The rock formed due
to the change in thenature and propertiesof the pre-existingrock is calledmetamorphic rock. Whenigneous rocks and
metamorphic rocks are subjected to high temperatureand stress for very long period of time, theygradually change their form and evolve as a new formof rock known as metamorphic rock. The process offormation of metamorphic rock is called metamorphism(examples: slate, marble, diamond, etc)
Identification Of Rocks
Location no.L4About 200m from the hanging bridge over the
Trishuli River along Thopal Khola i.e. in betweenlocation L2 and the hanging bridge. Following thingswe observed in this location
Sample no.1
S.N. Physical Properties
1 Sample number
01
2 Colour Greyish
3 Texture Non crystalline
4 Structures Foliation plane/slaty cleavage
5 Grain size Fine
6 Sp. Gravity Low to medium
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7 Acid test No reaction
8 Mineral comp.
9 Origin/rocktype
Metamorphic rock
10 Engineeringproperties
Low strength
Low blastability
Low drillability
11 Identification
Slate: saltic cleavage
12 Uses Roofing, in electrical industry as switch board, bases and various turned or shaped parts due to its insulating property.
13 Attitude ofthe rock:
S 009o E/84o
Location no.L5
Sample no.2
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S.N.
Physical Properties
1 Sample number 02
2 Color Dirtywhite
3 Texture Crystalline
4 Structures Bedding plane
5 Grain size Medium
6 Sp. Gravity Medium to high
7 Acid test Vigorously reacts with HCl inpowder form
8 Mineral comp. Calcite
9 Scratch test Scratched by hammer
10 Origin/rocktype
Sedimentary
11 Engineeringproperties
High strength
High blastibility
High drillability
12 Identification Dolomitic limestone
13 Uses Raw material for cement,
aggregates
14 Attitude ofrock
S 0080 E/ 850
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Location no.L8Sample no. 3
Amphibolites
S.N. Physical Properties
1 Sample number 03
2 Color Greish black
3 Texture Crystalline
4 Structures/cleavage
Massive/Foliationplane/slaty
5 Grain size Fine to medium
6 Sp. Gravity High
7 Acid test No reaction
8 Mineral comp. Amphibolite group
9 Origin/rock type Metamorphic
10 Engineeringproperties
High strength
High blastibility
High drillability
11 Identification Amphibole groups
12 Uses Can be used as good qualityaggregates
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Location no.L8:Sample no 4
Phyllite
S.N.
Physical Properties
1 Sample number 04
2 Color Silver white
3 Texture Crystalline
4 Structures/cleavage
Foliation plane/slaty
5 Grain size Medium to coarse
6 Sp. Gravity Medium
7 Acid test No reaction
8 Mineral comp.
9 Origin/rocktype
Metamorphic
10 Engineeringproperties
Low strength
High drillability
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Low blastability
11 Identification Phyllite
12 Uses Pavements, dry wall andslabing
Location no.L9 Sample no. 5
Quartzite
S.N. Physical Properties
1 Sample number 05
2 Color Dirty white
3 Texture Crystalline
4 Structures/cleavage
Foliation plane/slaty
5 Grain size Fine
6 Sp. Gravity Medium to high
7 Acid test No reaction
8 Mineral comp. Quartz
9 Origin/rocktype
Metamorphic
10 Engineeringproperties
High strength
Low drillability
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High blastsbility
11 Identification Quartzite
12 Uses For making reeling inhome applications,building stone, roadmetal, concreteaggregates
13 Attitude ofrock
S0180E/780
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PHOTOGRAPH
Figure 20: Sample no. 5
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Location no.L10 Sample no. 6
S.N. Physical Properties
1 Samplenumber
06
2 Color Silver white
3 Texture Crystalline
4 Structures Foliation plane
5 Grain size Fine to coarse
6 Sp. Gravity Low to medium
7 Acid test No reaction
8 Mineralcomp.
Garnet, chlorite,quartz, horn blend, talc
9 Origin/rocktype
Metamorphic
10 Engineeringproperties
Low strength,incompetent, harmful andundesirable rock
11 Identification
Garnitiferous Schist
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12 Uses Rock foundation,building stone, aggregatefor concrete, road material
13 Attitude of therock
S30oE/46o
PHOTOGRAPH
Figure 21: Sample no.6
Location no.L11Sample no. 7
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S.N.
Physical Properties
1 Sample number 07
2 Color White
3 Texture Crystalline
4 Structures Foliation plane
5 Grain size Coarse
6 Sp. Gravity High
7 Acid test No reaction
8 Mineral comp. Quartz, plagioclase,biotite, muscovite
9 Origin/rocktype
Metamorphic
10 Engineeringproperties
High strength
Low drillability
High blastability
11 Identification Augen Gneiss
12 Uses as flooring mill and forbuilding stone or material
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PHOTOGRAPH
Figure 22: Sample no.7
Location no.L12
Sample no. 8
S.N.
Physical Properties
1 Sample number 08
2 Color White
3 Texture Crystalline
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4 Structures No plane of mineralorientation,
no bedding plane
5 Grain size Coarse
6 Sp. Gravity High
7 Acid test No reaction
8 Mineral comp. Orthoclase,biotite,quart, plaeoclase,
muscobite
9 Scratch test Scratched by hammer
10 Origin/rocktype
Metamorphic
11 Engineeringproperties
High strength
High blastability
Low drillability
Isotropic
12 Identification
Granite
13 Uses As aggregates,foundations in theconstruction and as slab
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PHOTOGRAPH
Figure 23:Sample no.8
Location no.L14Sample no. 9
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S.N. Physical Properties
1 Sample number 09
2 Color Whitish
3 Texture Crystalline
4 Structures Bed plane/Foliationplane
5 Grain size Coarse
6 Sp. Gravity High
7 Acid test Vigorously react inpowder form
8 Mineral comp. Calcite
9 Scratch test Scratched by hammer
10 Origin/rocktype
Metamorphic
11 Engineeringproperties
Medium strength
High drillability
High blastability
12 Identification
Marble
13 Uses Used in cement factory,
In construction ofcivil engineering
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structures
14 Attitude ofthe rock
S15 o E/ 87 o
PHOTOGRAPH
Figure 24: Sample no.9
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River Channel Morphology
River patterns, or general shapes, depend on the geologic zone and the climate of the location. There are three river patterns: meandering, braided, and straight. A meandering pattern follows a winding, turning course. A braided pattern has connected channels that resemble a hair braid. Some river patterns are simply straight channels. Meandering andbraided are the most common patterns. Braided and straight patterns are usually located in the mountains or hills below the headwater zone of rivers, while meandering patterns is located in the middle and mouth zones of most rivers.
Meandering river morphology
A meandering river has looping bends of different sizes along its valley. Each bend is the result of sediment depositing on the inside of the bend. The topography of meandering river area is characterized by moderate relief, medium gradient andvelocity lower tthen straight river channel morphology. As sediment deposits gradually build up, a point bar forms on the inside of the bend. The point bar pushes the river flow against the outside bank of the bend, eroding the bank opposite the pointbar. Eventually the bend becomes so sharp that the river bypasses it, cutting a straighter path. The arc
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of the bend is left behind as the river moves past. The arc may form an oxbow lake, a pool of water enclosed by the arc and riverbank. A meandering river’s bed is usually covered with sand, while the floodplain is filled with silt and clay. Since the energy level of such river is medium, the erosional rate and the depositional rate of sediments is comparatively equal. Due to this phenomenon, the channel shifting is prominent in such type of river system.
Braided river morphology
Braided rivers look completely different from meandering rivers. The topography of the braided river area is characterized by low relief. The gradient is low, area widned, and water flow with lowvelocity. They have many channels that are constantlychanging position because of frequent changes in flowrate and sediment supply. The channels of a braided river change course frequently, so the river’s water may cover the entire floodplain on a regular basis. The sediments of braided rivers are usually gravel and cobbles. Sometimes a meandering river may change into a braided river in the middle zone if the supplyof sediment increases as a result of farming or grazing activities in the watershed.
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Straight river morphology
This type of river follows a straight path. The topography of the area is characterized by steep relief. The slope of the river is also high causing the flow velocity of water high , since the energy level of such river is high erosional rate is intensely higher than the deposition of sediments. Deep scouting along the path is higher than the side cutting. Straight rivers are not common. They are typically located in canyons in mountainous areas or exist as the result of engineering structures that force a river into a straight course.
Features developed by river channel morphology
Alluvial Fans and ConesThese are cone shaped accumulation of stream debris
that is commonly found at places where small intermittent streamlets coming down from hills enter the low lands. The apex of such a deposit points up hill and its slope may range from almost flat to as much as 50. When the slope of the deposits is below 10,the alluvial deposit is known as alluvial fan, and whenit is from 10-50, the deposit is known as alluvial cone. Alluvial fans and cones show contrasting patternsin distribution of fragments and particles of various sizes at their apices, peripheries and in the main body. Further repeated accumulations over an initial fan or cone contribute to its considerable growth. Alluvium is usually very porous and will be
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compressible if rich in clay and permeable if composed of gravel, sand or silt.
Flood Plain DepositsFloodwaters are invariably heavily loaded with
sediments of all types. When these waters overflow the banks and spread as enormous sheets of water in surrounding areas, their velocity gets checked everywhere due to obstructions. As a consequence they deposit most of the load in the form of a thick layer of mud, so commonly seen after major flood. Since such a process may get repeated year after year, the low lying areas surrounding major rivers are actually made up of the layers of mud deposits laid after a number offloods. These are generally level or plain in nature and extensive in area and are called Flood plains. All the plain around major rivers are actually flood plains. These are invariably very fertile in nature andhence have been supporting population. Two major types of flood plains known as convex flood plains and flat flood plains are known.
DeltasDeltas are defined as alluvial deposits of roughly
triangular shape that are deposited by the rivers at the points where they enter into the sea. Herodotus first used this term for the deposits of the river Nileat its entry into the Mediterranean Sea. Deltas are very complex in their structure. A number of fractures are involved in their formation, evolution and modification.
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Oxbow Lake:The isolated curve or loop shaped part of
meandering river often contains some supplies of water known as oxbow lakes in the shape of
curve.
FloodplainFloodplain is a flat region of a valley floor
located on either side of a river channel. A floodplain is built of sediments deposited by the river that flows through it and is covered by water during floods when the river overflows its banks. During most floods, just a portion of the floodplain is covered with water and only during infrequent, very large floods is the whole floodplain covered. Floodplains tend to develop on the lower and less steep sections of rivers.
Figure 25: Formation of ox-bow lake.
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River channel morphology in foodplainRiver channels in floodplains adopt two kinds of
patterns: meandering and braided. Meandering rivers consist of a single main channel that bends and loops. In some cases, the channel is so winding that the length along the channel is several times the straight-line distance along the river valley. Braided rivers have numerous distinct channels that repeatedly divide and then merge again downstream. While a meandering channel occupies only a small partof its floodplain at any one time, a braided river occupies much of the floodplain over the course of a year.
Both patterns migrate across the floodplain, removing sediments from their path and depositing them elsewhere. A braided river reworks the sediment in its floodplain very frequently as the various individual channels continually shift position. In meandering rivers, sediment is eroded on the outside of bends and on the downhill side of traverses and deposited on the inside of bends and on the uphill side of traverses. Over time, this causes meander loops to migrate downstream. If the movement of one meander loop overruns the next one downstream, then ameander cut-off, or chute, is formed. This causes thecourse of the channel to be shortened as the two meander loops join. The abandoned meander loop is gradually isolated as sediment is deposited at each end by the water flow in the main channel. This process eventually leads to the creation of an ox-bowlake. On average, about 290 km (about 180 mi) of the
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channel of the Mississippi River is abandoned throughthe formation of meander cut-offs every 100 years, but the overall channel length is not reduced becausethere is a compensating enlargement of other meanders.
Many interrelated factors determine the form taken by river channels and it is not precisely understood why some river channels have a meandering pattern and others are braided. Meandering channels are more common where the floodplain sediments are sand, silt, and clay. Braided channels are more common where the floodplain sediment is mostly gravelor where there is an increase in channel steepness. Abraided pattern also tends to be favored if the amount of water flowing in the river is highly variable or if the banks are easily eroded and can provide abundant sediment to the channel.
Engineering significance of different types of river channels
As we well know that the civil engineers have to deal with varieties of the river channel morphology for the construction of different structures as well as availability of the construction material. If we consider straight river channel morphology, then construction of masonry bridge foundation on river channel is not applicable as deep scouring is intensealong the path, whereas, the straight river channel
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has low side cutting, in such case arch bridge can bea good option. Similarly the construction of run off hydropower dam is an option. In meandering river if the bridge is constructed in a curve portion then thefoundation on the striking band may be affected. Instead the site of the bridge is selected on the straight potion of the meandering river.
Whereas, depending upon the construction materialavailable like granite boulders, gravity dam can be constructed in this type of morphology like KulekhaniHydropower Dam. In braided river condition, a span ofbridge is high with many pillars on the river path. In low land braided river morphology, the hydropower project is impracticable, due to low gradient and high sedimentation problem.
LocationL2, about 300 m from Malekhu suspension bridge towards Dhading Beshi.
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Sketch and Photograph
Figure 26: River Channel Morphology
ENGINEERING GEOLOGICAL DATACOLLECTION
Engineering geological data
There are some factors whose condition in case of rock are observed and recorded in order to determine the
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strength of the rock for laying foundation on it is simply known as engineering geological data. These dataalso helps us to determine the present condition and the nature of the rock. The data was collected in location no.1 about 50m from damaged bridge on the leftside of Malekhu River.
Importance of engineering geological data
Purpose specific geological data collected from field (rock mass) which can be quantified and used as design parameter. It is quantities diagnosis of an area. It must be purpose specific. Site investigation is the investigation of particular area for specific purpose data collection. It is very essential to draw any engineering geological map or to solve any geological problems.
We always deal with a rock mass not only with a block of rock. Rock mass means intact rock with its discontinuities. In many cases, the technicians are in dark in this aspect. He collects a piece of sample and takes it to the lab and concludes his result. This is not a correct way to publish any geological decision. In fact, it is much more important to know the entire rock mass up to our concern.
Rock Quality Designation (R.Q.D)It is expressed in percentage. The expression for RQD has is:RQD=115-3.3*Jv
Where Jv = Joint volume. i.e. number of joint per unit volume.
Spacing of discontinuityIt is expressed in cm and all the discontinuity is taken under considered area.
Aperture or separation of discontinuity
1. Tight (<1cm)2. Open (expressed in cm, all the data are taken)3. Wide (>30cm)
Infilling materials
Sand/slit/clay/calcareous material
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Persistence ( Continuity of discontinuity)
Roughness of discontinuity
1. Smooth2. Rough3. Undulated
Number of joint setThese are the number of parallel or nearly parallel sets of the joints in the rock mass.
Orientation of joint setExpressed including dip amount and dip direction, (i.e.dip amount/dip direction)
Ground water condition
1. Dry2. Dripping3. Seepage4. Flowing5. Damp/wet
Rock mass classification system
The rock mass classification system is the system of evaluating the composition and characteristics of the rock mass. The foundation stands on the rock and the properties of rock affects the stability of foundation.The problems related to these things can be solved using the rock mass classification system. This system helps to estimate the strength and deformation
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properties of the rock mass. There are four methods of rock mass classification.
Description of Rock mass classification system
Terzaghi’s Rock mass classificationThis classification is the earliest reference which is the descriptive classification.
The rock with no joints: intact rockThe rock with little strength along bedding surfaces: stratified rock.Rock mass jointed but cemented: moderately jointed rockJointed rock mass without any cementing of joints: blocky and seamy rockRock reduced to sand sized particles due to weathering: crushed rockRock with clay: squeezing rockRock squeezes primarily from mineral swelling: swelling rock.
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Rock quality designation index (RQD)D. U. Deere introduced a rock mass classification system based on the qualitative estimate of rock mass quality from drill core logs.
RQD=∑ofcorepieces>10cmlengthofcore
×100%
But in absence of core logs ,
RQD=115−3.3Jv,
which is suggested by Palmstom (1982) where Jv is sum of the number of joints per unit length of all discontinuities sets or simply the volumetric joint count.
Bieniawski’s geomechanics classification Bieniawski in 1976 published the details of rock
mass classification called the geomechanics classification and widely known as rock mass rating (RMR) system. During the study of rock mass classification this method has been adopted.
Six parameters are widely used in this system.
1. Intact rock strength2. RQD3. Spacing of discontinuities
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4. Orientation of discontinuities5. Condition of discontinuities6. Ground water condition
Different rating value has been provided to different parameters and the sum of all these parameters gives the final rating. The value of rating provides the class of the rock.
Rock mass classification based on RMR Class no. Rating value Rock quality
I 100-81 Very good rock
II 80-61 Good rock
III 60-41 Fair rock
IV 40-21 Poor rock
V <21 Very poor rock
Rock tunneling quality index (Q value)Barton et. al (1974) proposed this theory. The
value of Q varies on the logarithmic from 0.001 to 1000.
Q value is defined by:
Q= (RQD*Jr*Jw)/(Jn*Ja*SRF)
Where,
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RQD= Rock quality designation Jr= joint roughness number Jw= joint water reduction factor Jn= joint set number Ja= joint alternation number SRF= stress reduction factor
Engineering geological data observed in the field
Location no. 04:
Rock mass classification by RMR system (rock mass rating)
Sample no. 1
S.N. Parameters Properties rating Remarks
1. Rock type Sedimentary
2. Rock strength Medium to high 12
3. Weathering W1 5
4. R.Q.D. test 88% 17
5. Spacing of discontinuity (cm)
26,17,13,8,3,8,16,7,13 8
6. Separation Tight 6
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2nd class
Rock mass,
Good rock
7. Infilling materials Silt in traces 6
8. Persistence 2.5-3.5m 4
9. Roughness Rough 5
10. No. of joint set 2
11. Orientation of joint sets
S850W/590
N850W/59 0
5 Ground water condition
Dry 15
Total 78
Sample no.2
S.N. Parameters Properties rating Remarks
1. Rock type Sedimentary
2nd class
Rock mass,
Good rock
2. Rock strength Medium to high 12
3. Weathering W2 3
4. R.Q.D. test 88.6% 17
5. Spacing of discontinuity(cm)
9,20,40,18,2,56,45 8
6. Separation Tight 6
7. Infilling materials Clay 2
8. Persistence 0.8-2m 4
9. Roughness Very Rough 6
10. No. of joint set 3
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11. Orientation of joint sets
S840E/610
N640W/48 0
S180E/800
5 Ground water condition
Seepage 10
Total 68
Sample no.3
S.N. Parameters Properties rating Remarks
1. Rock type Sedimentary
1st class
Rock mass,
Very
Good rock
2. Rock strength High 15
3. Weathering W1 5
4. R.Q.D. test 82% 17
5. Spacing of discontinuity(cm)
10,7,2,3 15
6. Separation Tight 6
7. Infilling materials No 6
8. Persistence 1-2m 4
9. Roughness Rough 5
10. No. of joint set 3
11. Orientation of joint sets
S090E/840
N630W/76 0
N900W/460
5 Ground water condition
Dry 15
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Total 88
Photograph
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Objectives of rock mass classifications
Identify the most significant parameters influencing the behavior of a rock mass.
Divide a particular rock mass formulation intogroups of similar behavior – rock mass classes ofvarying quality.
Provide a basis of understanding thecharacteristics of each rock mass class
Relate the experience of rock conditions at onesite to the conditions and experience encounteredat others
Derive quantitative data and guidelines forengineering design
Provide common basis for communication betweenengineers and geologists.
Engineering significance of rock mass classifications:
Improving the quality of site investigations bycalling for the minimum input data asclassification parameters.
Providing quantitative information for designpurposes.
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Enabling better engineering judgment and moreeffective communication on a project.
Conclusions:At last, we have concluded that Malekhu proves to be
a good place for the study and interpretation of thegeology, its components and its significance in thefield of engineering. Actually, Malekhu, even small inarea, contains large amount of geological phenomenonand hence it can provide broad knowledge for thelearners.
Along Malekhu River, we found sedimentary rock andgradually metamorphosed from Phyllite to crystallineschist and along the way to Dhading, it graduallymetamorphosed to lime stone to Phyllite and then toslate.
Every major bed was dipped in north direction. Thisproved the tectonic movement is along the way from
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south to north. As the region lies in the zone of MainCentral thrust (MCT), there are evidences of differenttypes of tectonic activities such as unconformity,fold, fault, thrust, etc. within a small area.
Besides this, we have learnt different methods ofgeological data collection through geological compass.By, the rivers channel morphology, we had known how theriver flows, what are the factors affecting erosion anddeposition and how it occurs. Also, we were able togain board knowledge on the different landforms formedby rivers.
Consequently the field trip was so much hard but inreality it had provided us an opportunity to get closerto the real experience of practical study in the daysto come. This trip provided with a vivid knowledge ofthe geology which would otherwise be hardly possible.
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REFERENCES: Data collected during the field visit. Sketches drawn and photo taken in the field. www.geology.edu.np www.wikipedia.com www.google.com Journal of the Geological Society; 2008; v.
165; issue.2 Britannica 8.0(2009) Microsoft Encarta Engineering Geology:
