CE6301 ENGINEERING GEOLOGY VTHT

VELTECH HIGH TECH Dr.RANGARAJAN Dr.SAKUNTHALA ENGINEERING COLLEGE AVADI, CHENNAI DEPARTMENT OF CIVIL ENGINEERING LECTURER NOTES YEAR/SEM :II/III SUBJECT CODE/TITLE :CE6301/ ENGINEERING GEOLOGY FACULTY NAME :ANJALA.D

UNIT I PHYSICAL GEOLOGY

Geology in civil engineering – branches of geology – structure of earth and its composition – weathering of rocks – scale of weathering – soils - landforms and processes associated with river, wind, groundwater and sea – relevance to civil engineering. Plate tectonics

SCOPE OF GEOLOGY IN CIVIL ENGINERRING:  It is defined as that of applied science which deal with the application of geology for a safe, stable and economic design and construction of a civil engineering project.  Engineering geology is almost universally considered as essential as that of soil mechanics, strength of material, or theory of structures.  The application of geological knowledge in planning, designing and construction of big civil engineering projects.  The basic objects of a course in engineering geology are two folds.  It enables a civil engineer to understand the engineering implications of certain condition should relate to the area of construction which is essentially geological in nature.  It enables a geologist to understand the nature of the geological information that is absolutely essentially for a safe design and construction of a civil engineering projects.  The scope of geology can be studied is best studied with reference to major activities of the profession of a civil engineer which are  Construction  Water resources development  Town and regional planning

GEOLOGY IN CONSTUCTION FIELD PLANNING Topographic Maps:  It’s gives details of relief features and understands the relative merits and demerits of all the possible sides of proposed structure. Hydrological maps:  This map gives broad details about distribution and geometry of the surface of water channel. Geological maps :  The petrological characters and structural disposition of rock types this gives an idea about the availability of materials for construction.

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Introduction about Lithosphere:  Litho is a Greek word, which means stone. Accordingly the lithosphere is the part of the earth, which is solid crust.  The thickness of lithosphere is approximately 50 km. The crustthickness is not the some at allplaces.  It is thicker in the continent and thinner on the oceanfloors. Lithosphere is a source of various minerals.  It contains variety of landforms such as mountains.plateous valleys, plains. Plates: The surface of the earth is the crust of the earth. It is made of interlocking pieces called plates. The continents and oceans rest in these places and are separated by wide cracks. The plates move constantly. subdivisions in geology The subdivisions are:  Physical geology  Geomorphology  Mineralogy  Petrology  Historical geology  Economic geology  Geohydrology  Engineering geology  Metrolog Crust: Early in the 20 th century the reality of earth crust was demonstrated by a scientist named Mohorovicic.He noted that in measurements of seismic wave arriving from an earthquake, those focus lay within 40km of the surface, seismographs within 800 km of the epicenter. Recorded two distinct sets of P and S-waves. He concluded that one par of waves must have travelled from the focus to the station by a direct path whereas the other pair of waves had arrived slightly later because they had been refracted. There are two types of crust:  Continental crust  Oceanic crust. Continental Crust:  The continental crust consists of two layers separated by a well-defined discontinuityknown as Conard discontinuity. The layers have been defined on the basis of seismic wavesvelocities and densities.  In the upper layers the velocity of seismic waves corresponds to the velocity found byexperimental to be characteristic of granite. Hence they are called as Granitic or silica layer. Oceanic Crust:  The earths crust beneath the oceans consist of a low velocity layer of deep sea sediments about 300-400m thick in pacific and 600-700 m in the Atlantic.  The Layer of intermediate velocity called basement about 0,8 km thick, composed of compacted and indurated sediments and lave flows.

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 The third layer is called the oceanic layer about 4.1 to 5.8 km thick and certain  composition. This three-layered oceanic crust is generally 5 to 8 km thick. Mantle:  Materials making the earth become quite different in properties at the base of the crust.  This depth below the surface of the earth at which a striking change in the properties of the  materials is observed has been named as Mohovorovicic discontinuity.  In geological literature itis often referred as M-discontinuity or simply as Moho.Hence mantle is that zone within theearth that starts from M-discontinuity and continues up to a depth of 2900km.Mantle is made up of extremely basic material called aptly ultra basic that is very rich iniron and magnesium but quite poor in silica. The material of the mantle is believed to be variably viscous in nature . Core:  It is the third and the innermost structural shell of the earth as conclusively proved by the  seismic evidence. It starts at a depth of 2900 km below the surface and extends right up to the  centre of the earth, at a depth of 6370km.  The core remains a mystery in many ways. Within the core the physical nature ands  composition of the material is not uniform throughout its depth. It has a very high density at mantle core boundary above 10g/cc.The outer core behaves lime a liquid towards the seismic waves. The inner core starting from 4800km and extending up to 6370 m is of unknown nature but definitely of solid character and with properties resembling top a metallic body. Atmosphere: The outer gaseous part of the earth starting from the surface and extending as far as700km and even beyond is termed atmosphere. It makes only about one million part of the totalmass of the earth. Stratosphere:  It is the second layer of the atmosphere starting from the tropopause and extending up to  san average height of 50km.The stratosphere differs from the lower layer in following respects.  The temperature becomes constant for a height of 20km and then starts increasing.  It contains almost the entire concentration of OZONE GAS that occurs above the earth  form of a well-defined envelope distinguished as the Ozone layer.  The stratosphere itself has a layered structure and there is no significant mixing or turbulence of gases in this layer. Branches of geology: Geology is a relatively recent subject. In addition to its core branches, advances in geology in allied fields have lead to specialized sciences like geophysics, geochemistery, seismology, oceanography and remote sensing. Main and Allied branches of geology: The vast subject of geology has been subjected into the following branches: Main Branches Allied Branches Physical geology Engineering geology Mineralogy Mining geology Petrology Geophysics

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Structural geology Geohydrology Stratigraphy Geochemistry Paleontology Economic geology Physical geology: This is also variously described as dynamic geology, geomorphology etc. It deals with:  Different physical features of the earth, such as mountains, plateaus, valleys, rivers.lakes glaciers and volcanoes in terms of their origin and development.  The different changes occurring on the earth surface like marine transgression, marine regression, formation or disappearance of rivers, springs and lakes.  Geological work of wind, glaciers, rivers, oceans, and groundwater ands their role inconstantly moulding the earth surface features  Natural phenomena like landslides, earthquakes and weathering. Mineralogy: It deals with the study of minerals. Minerals are basic units with different rocks andores of the earth are made up of.Details of mode of formation, composition, occurrence, types, association, properties uses etc. of minerals form the subject matter of mineralogy. For example: sometimes quartzite and marble resemble one another in shine, colour and appearance while marble disintegrates and decomposes in a shorter period because of its mineral composition and properties.

Petrology: Petrology deals with the study of rocks. The earths crust also called lithosphere is made up of different types of rocks. Hence petrology deals with the mode of formation, structure, texture, composition, occurrence, and types of rocks. This is the most important branch ofgeology from the civil engineering point of view. Structural geology: The rocks, which from the earths crust, undergo various deformations, dislocations anddisturbances under the influence of tectonic forces. The result is the occurrence of different geological structures like folds, fault, joints and unconformities in rocks. The details of mode of formation, causes, types, classification, importance etc of these geological structures from thesubject matter of structural geology. Stratigraphy: The climatic and geological changes including tectonic events in the geological past canalso be known from these investigations. This kind of study of the earth’s history through thesedimentary rock is called historical geology. It is also called stratigraphy (Strata = a set ofsedimementary rocks, graphy description). Economic geology: Minerals can be groupedas general rock forming minerals and economic minerals. Some of the economic minerals like talc, graphite, mica, asbestos, gypsum, magnesite, diamond andgems. The details of their mode of formation, occurrence, classification. Association, varieties,concenteration, properties, uses from the subject matter of economic geology. Further based onapplication of geological knowledge in other fields there is many other allied branchescollectively called earth science. Some of them described here are:

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 Engineering geology  Mining geology  Geophysics  Geohydrology  Geochemistry Engineering geology: This deals with the application of geological knowledge in the field of civil engineering,for execution of safe, stable and economic constructions like dams, bridges and tunnels. Mining Geology: This deals with the application of geological knowledge in the field of mining. A miningengineer is interested in the mode and extent of occurrence of ores, their association, propertiesetc. It is also necessary to know other physical parameters like depth direction inclinationthickness and reserve of the bodies for efficient utilization. Such details of mineral exploration,estimation and exploration are dealt within mining geology. Geophysics: The study of physical properties like density and magnetism of the earth or its parts. Toknow its interior form the subject matter of geophysics. There are different types ofgeophysical investigations based ion the physical property utilized gravity methods, seismic methods,magnetic methods. Engineering geophysics is a branch of exploration geophysics,which aims atsolving civil engineering problems by interpreting subsurface geology of the area concerned.Electrical resitivity methods and seismic refraction methods are commonly used in solving civil engineering problems. Geohydrology: This may also be called hydrogeology. It deals with occurrence, movement and nature ofgroundwater in an area. It has applied importance because ground water has many advantagesover surface water. In general geological and geophysical studies are together taken up forgroundwater investigations. Geochemistry: This branch is relatively more recent and deals with the occurrence, distribution,abundance, mobility etc, of different elements in the earth crust. It is not important from the civilengineering point of view. weathering and its significance in engineering construction Weathering is defined as a process of decay, disintegration and decomposition of rocksunder the influence of certain physical and chemical agencies. Disintegration: It may be defined as the process of breaking up of rocks into small pieces by themechanical agencies of physical agents. Decomposition: It may be defined as the process of breaking up of mineral constituents to form newcomponents by the chemical actions of the physical agents. Denudation: It is a general term used when the surface of the earth is worn away by the chemical as well as mechanical actions of physical agents and the lower layers are exposed. The process of weathering depends upon the following three factors:  Nature of rocks

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 Length of time  Climate Two Chief types of weathering are commonly distinguished on the basis of type of agency involved in the process and nature of the end product. They are:  Physical or mechanical weathering  Chemical weathering Physical weathering:  It is the physical breakdown of rock masses under the attack of certain atmospheric agents.  A single rock block is broken gradually into smaller irregular fragments and then into particles of still smaller dimensions.  It is the most active in cold, dry and higher areas of the earth  surface Temperature variations are responsible to a great extent of physical weathering. Thermal effects: The effect of change of temperature on rocks is of considerable importance in arid andsemi arid regions where difference between daytime and nighttime temperature is often veryhigh. Such temperature fluctuations produce physical disintegration in a normally expected manner. Expansion on heating followed by contraction on cooling. When the rock mass islayered and good thickness additional disturbing stresses may be developed into by unequalexpansion and contraction from surface to the lower regions. The rock sometimes is found tobreak off intoconcentric shells. This process is known as exfoliation.When weathering occurs part of the disintegratedrock material is carried away by running wateror any other transporting agent. Someof them are left on the surface of the bedrock as residualboulders. It is often seen that boulders have an onion like structure. This kind of weathering iscalled spheroidal weathering. Chemical weathering: The chemical decomposition of the rock is called chemical weathering which is nothingbut chemical reaction between gases of the atmosphere and minerals of the rocks. The chemicalchanges invariably take place in the presence of water generally rainwaterin which aredissolved many active gases from the atmosphere like C02, nitrogen, Hydrogenetc.Theseconditions are defined primarily by chemical composition of the rockshumidity and theenvironmental surrounding the rock under attack.Chemical weathering is essentially a process of chemical reactions between gases of theatmosphere and the surface rocks. For example: 1) 2CaCO3 + H2O + CO2 ------2 Ca (HCO3) 2 2) CaSO4 + 2H2O ------CaSO42.H2O Engineering importance of rock weathering: As engineer is directly or indirectly interested in rock weathering specially when he hasto select a suitable quarry for the extraction of stones for structural and decorative purposes. Theprocess of weathering always causes a lose in the strength of the rocks or soil.For the construction engineer it is always necessary to see that:  To what extent the area under consideration for a proposed project has been affected byweathering and  What may be possible effects of weathering processes typical of the area on the construction materials

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Major geologicalfeatures The earth is surrounded by an envelop of gases called the atmosphere. The movement ofthe atmosphere in a direction parallel to the earth surface is wind.i.e the air in motion is calledwind whereas the vertical movement s of the atmosphere are termed as air currents. Erosion by wind and developed features: Wind erosion is generally caused by two erosion processes:  Deflation  Abrasion. Deflation: Deflation is the process of simply removing the loose sand and dust sized particles from as area, by fast moving winds. Wind deflation can successfully operate in comparatively dryregionswithlittle or no rainfall and where the mantle is unprotected due to absence ofvegetation. Such a removal of loose fine particles may at certain places leave a denuded surfaceconsistingmostly of hard rocks or coarse materials like gravel and is called lag gravel. This gravel layerprevents further deflation. Abrasion: The wind loaded with such particles attains a considerable erosive power which helps aconsiderable er4osive power which helps in eroding the rock surfaces by rubbing and grinding actions and produce many changes. This type of wind erosion is known as abrasion.Vertical column of rocks are thus more readily worm out towards their lower portions and aresult pedestal rocks are formed which wider tops have supported on comparatively narrowerbases. Such type of rock formations is called Pedestal or Mushroom rocks. Transportation by wind: The total sediment load carried by a wind can be divided into two parts.  Bed load  Suspended load The larger and heavier particles such as sands or gravels, which are moved by the winds but not lifted more than 30 to 60 cm of the earth surface constitute the bed load. Whereas the finer clay or dust particles which are lifted by the moving winds by a distance of hundreds of meters above the earths surface constitute the suspended load. Deposition of sediment by wind and the developed features: The sediments get dropped and deposited forming what are known as Aeolian deposits. There are two types of Aeolian deposits; a) Sand dunes b) Loess Sand dunes: Sand dunes are huge heaps of sand formed by the natural deposition of wind blown sand sometimes of characteristics and recognizable shape. Such deposits are often found to migrate from one place to another due to change in the direction and velocity of wind. The active dunes can be divided into three types:  Barchans or Crescent shaped dunes  Transverse dunes  Longitudinal dunes Barchans: These dunes that look like a new moon in plan are of most common occurrence. They are triangular in section with the steep side facing away from the wind direction and inclined at an

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angle of about 300 to 330 to the horizontal. The gently sloping side lies on the windward side, and makes an angle of about 10 to 150 with the horizontal. They may have variable sizes, with a generally maximum height of about 335 meters and horn to horn width of say 350 meters. Transverse Dunes: A transverse dune is similar to a barchans in section but in plan it is not curved likebarchans such that its longer axis is broadly transverse to the direction of the prevailing winds. Longitudinal dunes: Longitudinal dunes are the elongated ridges of sand with their longer axis broadly parallel to the direction of the prevailing wind. When seen in the side view they will appear to be triangular on an average they may be 3 m height and 200 m long. Loess: The finest particles of dust travelling in suspension with the wind are transported to aconsiderable distance. When dropped down under favourable conditions these have been found to accumulate in the different constituents the form of paper-thin laminae, which haveaggregated together to form a massive deposit known as Loess.

Engineering considerations: In general no site is selected for any type of important work on the moving dunes because such dunes are always a source of trouble to an engineer. It has been experienced that sometimes the moving dunes damage certain important works. But if an engineer is compelled to select such a site, special methods should be adopted to check the motion of the moving dunes. For ex:Either to construct windbreaks or growing vegetation on the surrounding areas. Hydraulic action: It is the mechanical loosening and removal of the material from the rocks due to pressure exerted by the running water. The higher the velocity the greater is the pressure of the running water and hence greater is its capacity to bodily move out parts of the rock or grains of soil from the parent body occurring along its base or sides. The river water flowing with sufficient velocity often develops force strong enough to disintegrate a loose rock, displace the fragments so created and lift them up and move forward as part of bed load. Cavitation: It is distinct and rare type of hydraulic action performed by running water. It isparticularly observed where river water suddenly acquires exceptionally high velocity such as at the location of a waterfall. In other words there is a spontaneous change fro a liquid to vapour state and back to liquid state at that point. The phenomenon of cavitations is also observed in hydropower generation projects. Abrasion: It is the principal method of stream erosion and involves wearing away of the bedrocks and rocks along the banks of a stream or river by the running water with the help of sand grain, pebbles and gravels and all such particles that are being carried by its as load. These particles grains and rock fragments moving along with river water are collectively known as tolls oferosion. The river valleys, water falls, escarpments, gorges and canyons and river terraces are some of the so well known examples developed principally by river abrasion. Attrition: This term is used for wear and tear of the load sediments being transported by a moving

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT natural agency through the process of mutual impacts and collisions which they suffer during their transport. Every part of the sediment in load in suspension or being moved along the bed of the stream receives repeated impacts from other particles,. Due to these mutual collusions, the irregularities and angularities of the particles are worn out. These become spherical in outline and rounded and polished at the surface. Some of the fragments any eventually get reduced to very fine particles that rea easily carried along with the running water for considerable distances. Corrosion: The slow built steady chemical action of the stream water on the rocks is expresses by the term corrosion. The extent of corrosion depends such on the composition of rocks and also on the composition of flowing water. Thus all rocks are not equally susceptible to corrosive action of stream water. Limestones, gypsum and rock salt bodies are soluble in water to varying degrees. The steam may hardly corrode sandstones, quartzites, granites and gneisses. causes, classification of earthquake: The physical forces the surfaces are rearranging rock materials by shifting magmas about altering the structures of solid rocks. The adjustment beneath the surface however involve various crystal movements, some of which because of suddenness and intensity produce tremors in the rocks and they are known as earthquake. The science dealing with the study of earthquakes in all their aspects is called seismology. Focus and epicenter: The exact spot underneath the earth surface at which an earthquake originates is known as its focus. These waves first reach the point at the surface, which is immediately above thefocus or origin of the earthquake. This point is called epicenter. The point which is diametricallyopposite to the epicenter is called anticenter. Intensity and magnitude: Intensity of an earthquake may be defined as the ratio of an earthquake based on actual effects produced by the quakes on the earth.Magnitude of a tectonic earthquake may be defined as the rating of an earthquake basedon the total amount of energy released when the over strained rocks suddenly rebound, causingthe earthquake. Causes of earthquake: The earthquake may be caused due to various reasons, depending upon it intensity.Following causes of earthquake are important: 1. Earthquakes due to superficial movements: The feeble earthquakes are caused due to superficial movements.i.e, dynamic agencies, and operation upon surface of the earth.  The dashing waves cause vibrations along the seashore.  Water descending along high water falls, impinges the valley floor and causes vibrations along the neighbouring areas.  At high altitudes the snow falling down is an avalance.also causes vibrations along the neighbouring areas. Earthquake due to volcanic eruptions: Most of the volcanoes erupt quietly and as consequence, initiate no vibration on the adjoining area. But a few of them when erupt, cause feeble tremors in the surface of the earth.But there may be still a volcanic eruption may cause a severe vibration on the adjoining area and have really disastrous effects. Earthquake due to folding or faulting:

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The earthquakes are also caused due to folding of the layers of the earth’s crust. if theearthquakes are caused due to folding or faulting then such earthquakes are more disastrous andare known as tectonic earthquakes and directly or indirectly change the structural features of the earth crust. Classification of earthquakes: Earthquakes are classified on a no. Of basis. Of these the depth of focus, the cause oforigin andintensity are important. a) Depth of focus: Three classes of earthquakes are recognized on this basis, shallow, intermediate and deepseated. In the shallow earthquakes the depth of focus lies anywhere up to 50 km below the surface. The intermediate earthquakes originate between 50 and 300 km depth below the surface. b) Cause of origin: i) Tectonic earthquakes are originated due to relative movements of crystal block onfaulting, commonly, earthquakes are of this type. ii) Non tectonic earthquakes: that owes their origin to causes distinctly different fromfaulting, such as earthquakes arising due to volcanic eruptions or landslides. C) Intensity as basis: Initially a scale of earthquakes intensity with ten divisions was given by Rossi andferel.Which was based on the sensation of the people and the damage caused. However it wasmodified by Mercalli and later by wood and Neumann. Engineering considerations: The time and intensity of the earthquake can never be predicted. The only remedy thatcan be done at the best, it is provide additional factors in the design of structure to minimize thelosses due to shocks of an earthquake. This can be done in the following way:  To collect sufficient data, regarding the previous seismic activity in the area.  To assess the losses, which are likely to take place in furniture due to earthquake shocks  To provide factors of safety, to stop or minimize the loss due to sever earth shocks.  Following are the few precautions which make the building sufficiently earthquake proof.  The foundation of a building should rest on a firm rock bed. Grillage foundations should preferably be provided.  Excavation of the foundation should be done up to the same level, throughout the  building.  The concrete should be laid in rich mortar and continuously Masonry should be done with cement mortar of not les than 1:4 max.  Flat R.CC slab should be provided.  All the parts of building should be tied firmly with each other.  Building should be uniform height.  Cantilivers, projections, parapets, domes etc, should be provided.  Best materials should be used. Ground water Groundwater hydrology may be defined as the science of the occurrence, distribution and movement of water below the surface of the earth. Ground water is the underground water that occurs in the saturated one of variable thickness and depth below the earth’s surface.Groundwater is an important source of water supply throughout the world. Its use in irrigation,industries, urban and rural home continues to increase. Origin of ground water:

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Almost all groundwater can be thought of as a part of hydrologic cycle, including surfaceand atmospheric waters. Connate water is water entrapped in the interstices of sedimentary rockat the time it was deposited. It may have been derived from the ocean or fresh water sources andtypically is highly minimized.New water of magmatic, almost all ground water can be thoughtof as a part of the hydrologic cycle, including surface volcanic or cosmic origin added to theterrestrial water supply is juvenile water. Ground water constitutes one portion of the earth water circulatory system known as the hydrologic cycle. Water bearing formations, of the earth crust act as conduits for transmission and as reservoirs for storage of water. Water enters these formations from the ground surface or form bodies of surface water After which it travels slowly for varying distances until it returns to the surface by action of natural flow, plants or man. Ground water emerging into surface stream channels aids insustaining stream flow when surface runoff is low or non-existent. Similarly water pumped fromwells represents the sole water source in many regions during much of every year. All ground water originates as surface water. Principal sources of natural recharge include precipitation, stream flow, lakes and reservoirs. Other contributions known as artificialrecharge occur from excess irrigation, seepage from canals and water purposely applied to augment groundwater supplies. Discharge of ground water occurs when emerges from underground. Most natural discharge occurs as flow into surface water bodies such as streams,lakes and oceans. Flow to the surface appears as spring. Groundwater near the surface may return directly to the atmosphere by evaporation from the soil and by transpiration from vegetation. Occurrence of ground water: Ground water occurs in permeable geologic formations known as aquifers. ie, formations having structures that permit appreciable water to move through them under ordinary field conditions. Ground water reservoir and water bearing formation are commonly used synonyms. An aquitard is a formation, which only seepage is possible and thus the yield is insignificant compared to an aquifer. It is partly permeable. An acquiclude is an impermeable formation which may contain water but incapable of transmitting significant water quantities. An aquifugeis an impermeable formation neither containing not transmitting water. Porosity: The portion of a rock or soil not occupied by solid mineral matter may be occupied by groundwater. These spaces are known as voids, interstices, pores or pore space. Because interstices can act as groundwater conduits they are of fundamental importance to the study of groundwater. Typically they are characterized by their size, shape, irregularity and distribution. Original interstices were created by geologic process governing the origin of he geologic formation and are found in sedimentary and igneous rocks. Secondary interstices developed after the rock was formed. Capilary interstices are sufficiently small so that surface tension fo4ces will hold water within them. Depending upon the connection of interstices with others, they may be classed as communicating or isolated. The amount of pore space per unit volume of the aquifer material is called porosity.

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Permeability: As stated above the ground water is stored in the pores of rock and will hence beavailable in the ground rocks, only if they are sufficiently porous. The porosity of the rock, thusdefining the maximum amount of water that can be stored in the rock. In fact the water can enterinto a rock only if the rock permits the flow of water through it, it depends on whether the rock ispermeable or not. The size of the pores is thus quite an important factor and it should besufficiently large to make the rock permeable. Vertical distribution of groundwater: The subsurface occurrence of groundwater may be divided into:  Zones of saturation  Zones of aeration In the Zones of Saturation water exists within the interstices and is known as the groundwater.This is the most important zone for a groundwater hydraulic engineer, because hehas to tap outthis water. Water in this zone is under hydrostatic pressure. The space above the water and belowthe surface is known as the zone of aeration. Water exists in this zone by molecular attraction.This zone is also divided into three classes depending upon the number of intersticespresent. The capillary fringe is the belt overlying the zone of saturation and it does contain some interstitial water and is thus a continuation to the zone of saturation while the depth from the surface, which is penetrate. GEOLOGICAL WORK OF EARTHQUAKE  An earthquake is a sudden vibration of earth surface by rapid release of energy  This energy released when two parts of rock mass move suddenly in relation of to eachoher along a fault. EFFECTS OF EARTHQUAKE:  Buildings are damaged  Roads are fissured, railway lines are twisted and bridges are destroyed  Rivers change their coarse  Landslides may occur in hilly region. TERMINOLOGY: FOCUS:  The point of origin of an earthquake within the earth crust is called focus.  It radiates earthquake waves in all direction EPICENTRE:  The point lying vertically above the earth surface directly above focus is called epicentre.  In the epicentre the shaking is most intense  The intensity gradually decrease ISOSEISMAL LINES:  The line connecting points of equal intensity on the ground surface are called isosesimal lines EARTHQUAKE INTENSITY:  It is a measure of the degree of distraction caused by an earthquake  It is expressed by a number as given in the earthquake intensity scale

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SESIMOGRAPHS:  Seismographs are instruments which detect and record earthquakes. EARTHQUAKE WAVES (SEISMIC WAVES):  P-Waves(primary waves)  S-Waves(secondary waves)  L-Waves (surface waves) During earthquake elastic waves are produced are called seismic waves. P-Waves:  These are longitudinal waves having short wavelength  They travel very faster and reach seismic station first  Their velocity is 1.7 times greater than s-waves  They passes through solid, liquid, gaseous medium.

S-WAVES:  These are shear waves which are traverse in nature.  They travel only in solid medium.

L-WAVES:  When p and s- waves reached earth surface they are called l- waves.  Here velocity is much less.

CLASSIFICATION OF EARTHQUAKE: CLASSIFICATION –I: Depending on mode of origin 1. DUE TO SURFACE CAUSES: Generated by land slopes and collapse of root of underground waves 2. DUE TO VOLACANIC CAUSES: It may also produce earthquake but very feeble. 3. DUE TO TECTONIC PLATES: Most numerous and disastrous and caused by shocks originated in earth crust due to sudden movement of faults. CLASSIFICATION-II: Depending on depth of focus 1. SHALLOW FOCUS: Depth of focus upto 55kms. 2. INTERMEDIATE FOCUS: Depth between 55-300kms. 3. DEEP FOCUS; Depth from 300-600kms. PHYSIOGRAPHIC DIVISION OF INDIA: India can be divided into 3 main division which may differ from one another in physiography, stratiography and structure. 1. Peninsular

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2. Indo-gangetic plain 3. Extra peninsular India PENINSULAR: It lies to the south of plain of India of ganga river Physiography: Peninsular has extremely various physiography.they are plateaus, fold mountains, valleys and coastal plains. Weatern ghats which form a premonient physiographic features Structure: Peninsular: India is nearly a stable pleatue which has unaffected by the orogenic movements The normal and block faulting is however common Stratigraphy: Peninsular is primarily made up of rocks of Archean and Precambrian age The Archean rocks have been metamorphosed to varying degree QUARTZ GROUP: It is an important rock forming mineral next to feldspar It is a non- metallic efractory mineral It is a silicate group Physical Properties Of Quartz: Crystal System: Hexagonal Habit: Crystalline Or Amorphous Fracture: Conchoidal Hardness: 7 Specific Gravity: 2.65-2.66(Low) Streak: No Transparency: Transparent/Semi-Transparent/Opaque Polymorphism Transformation: Quartz VARIETIES: Pure quartz is always colourless and transparent Presence of impurities the mineral showing colour they Amethyst: purple or violet Smoky quartz: shades of grey Milky quartz: light brown, pure white, opaque Rose quartz: rose cryptocrystalline forms of quartz: chalcedony: amorphous, waxy lustre agate: a banded , variety having different colours jasper: dull red, yellow, massive flint: dark grey, conchoidal fracture opal: amorphous quartz family minerals primary: Recrystalization process

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PLATE TECTONICS The theory of plate tectonics provides explanations for the past and present day tectonic behaviousof the Earth, particularly the global distribution of mountains seismicity, and volcanism in a series of linear bells, seafloor spreading, polar wandering and continental dirft. From several lines of thought andevidences it is learnt that all of the natural phenomena of the earth might be the result of a single basicmechanism, i.e., convection in the mantle. How convection could cause such natural phenomena is discussed later in the chapter. THE CONCEPT  The theory of plate tectonics supposes that the sphere of the earth is made up of 7 major andseveral minor plates which are in constant motion relative to each other.  The motion of the plates refer tothe rigid slabs of the continental and oceanic crust that slides over the plastic zone of asthenosphere of theupper mantle  A fractures egg shell forms a good analogy to the spherical plates of the earth.These plates are bounded by active linear zones causing volcanism and earthquakes. HISTORICAL BACKGROUND  The theory of plate tectonics has been a recently developed theory. Recent advancement in the  ocean floor studies and rock magnetism piled information on the nature of the seafloor. As with thegrowing data has grown the number of workers in the same filed.  Constitutions made by severalindividuals collectively gave birth to the theory of plate tectonics. At present even scientists from Russianschool who at first were against the theory, begin to show faith in the theory on seeing the evidencesaccumulating every day.  However there are a few flaws in the theory which are yet to the reasonablyexplained by the theory. Thus it may need a modification to answer all questions about the earth.Thetheory of plate tectonics has a fore runner of continental dirft.  Thus the entire idea that the Earth’s externalskin is subject to motion has come in to the minds in scientists when they observed the striking similarity ofthe opposite coasts of South America and Africa.In 17th century Francis Bacon wondered about the coastline matching.  But no work was done tilllate 19th Century.  When the world map was redrawn in 19th century the spirit of questioning of matchingcoasts got fire. Antonio snider pelligrini (1858, French), Frank B.Taylor (1901, American) and affredWegener (1915, German) contributed a lot to the idea of lateral motion of the continents over the face ofthe earth (chapter 22).  During 1950s magnetic data become available in support of continental drift andseafloor spreading.  Later it is understood that the continents themselves do not move but they are merepassengers over the sliding lithospheric slabs driven by the spreading seafloor. In 1968,Jason morganreplaced the title ‘new global tectonics’ by a new terminology ‘plate tectonics’.  Despite a few shortcomings the theory of plate tectonics gains momentum among the world scientists day by day by the overwhelmingevidences. The following sections deal in details about the plate tectonics.

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ELEMENTS OF TECTONISM  Seismology Permitted an insight into the Earth. As per the seismic data the Earth is composed of  a few layer of different composition, density and physical nature.  The earth consists of three Principallayers, namely crust, mantel and Core.  Crust is divisible into oceanic and continental crust. The earth’smovements involve the upper mantle also. in the upper mantle is a layer called low velocity zone which behaves like a fluid. Thus it Possesses a plastic flow. The layer is also known as asthenosphere.  Continental Crust, Oceanic crust and a part of upper mantle constitute a plate which a rigid part of thelithosphere.  Plates overlie the asthenosphere. Any movement in the underlying asthenosphere affects the plates. CHARACTERISTICS OF PLATES  A Plate consists of crust and a part of upper mantal.  Size and Shape of the plates are not constant.  One large plate may be fragmented into many small plates may unit to form a large one.  plates are spherical of curved and are independent.  Thickness of plates vary.It is 70 km beneath oceans and 150 km beneath continents.  Plates are bounted by different boundaries distinguished by the relative motion of the adjacent plates.  Plates are enclosed by Features like mid-oceanic ridges , oceanic trenches great faults and fold mountain belts.  The length of the boundary is variable.  Plates move with respect to each other and to the axis of rotation.  Plates move with different velocity and in different directions. Even different parts of the  same plate move at different velocities.  Plate margins are subject to deformation .but interior of the plate is free from deformation.  plates bearing continental crust will not be consumed at the boundaries.  Plates and boundaries are not permanent features. WORLD PLATES Geographical plates of the Earth are recognized as follows. Seven plates are larger and many others are smaller . LARGE PLATES  Antarctic plate  Pacific plate  Eurasian plate  African plate  North American Plate  South American Plate  indian/Australian plate SMALL PLATES  China Plate  Philippine Plate  Arabian Plate

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 Iran Plate  Nazca Plate  Cocos Plate  Caribbean Plate 8. Scotia Plate PLATE BOUNDARIES The surficial trace of the zone of motion is known as plate boundary. The end of the plate is calledplate margin. Figure 20.2 shows the boundary and the margin There are three types of plate boundaries.These are recognized on the basis of the movement associated with the plate junctions. They are: 1.Divergent or Constructive boundaries or sources 2. Convergent or Destructive boundaries or Sinks 3.Transform fault boundaries or conservative boundaries. With the help of seismic observations and / or magnetic lineation’s plate boundaries are mapped. And they are also used to find the direction and the velocity of plate motion. DIVERGENT BOUNDARY Long the middle of the ocean floor their rises a ridge with a central ‘V’ shapped valley. Theboundary line that separates the two plates runs along the valley bottom. Materials of the twoflanks ofthese mid oceanic ridges move away from each other. This boundary is known as divergent boundary asthe plates diverge with reference to the boundary line. But they are never separated. Because newmaterial is poured out continuously and is accreted to the moving plate margins material is symmetrically divided into two halves and mobilised. The symmetry may beproduced in thisway: A new ribbon of material is added to the margins of separating plates. The rigidity of the material islower and lower as the centre of the ribbon is approached. Splitting may occur along the line of weak zone.Thus when the ribbon is subjected to tensional forces (because of the mobile plates) it is brokensymmetrically as the plane of weakness occupies the central part of the ribbon. CONVERGENT BOUNDARY This boundary is developed as two plates converge towards each other and thus it is known as Convergent boundary. Since land area is lost along this type of boundary, it is known as destructiveboundary. For the reason that the material is being sunken at these boundaries they are also known assinks. Convergent Boundaries are marked by deep sea trenches and fold mountain belts. They may beLocated along the northern and western border of the Pacific forming Aleutian trench, Japan trench andTonga trench and Tonga trench, Western continent slope of the South America forming Eru-Chile trench,Himalayas f India, Mediter- tanean trench and java trench. The convergence of plates occur in two ways: 1.subduction And 2. Continental collision depending upon the nature of plates that collide. Three cases of plate collision my be expected accordingly the type of convergence differs as follows. Crustal Types Of Plates Type Of Convergence 1. Oceanic and oceanic Subduction 2.Oceanic and Continental Subduction 3.Continental and Continental Continental Collision  When both the colliding plates hold oceanic crust any one of the plates slides down the other  plates slide at approximately 45 degrees.

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 The process of sliding of one of the plates beneath the otheralong the convergent boundary is known as subduction.  When the colliding plates are oceanic andcontinental, then it is always the oceanic plate that is subducted beneath the continental.  It happens sobecause of the greater density of the oceanic crust of the descending plate. The plate being made up ofcontinental crust is lighter and always tend to float over the oceanic crust holding plate  When both thecolliding plates are composed of continental crust neither/ of the plates slips down because of low density.  But on collision continental crust is evolved into fold mountain systems. A classic example of such acontinental collision belt is the Himalayan belt, produced during the Cenozoic Era by the convergence ofthe Indian plate with Eurasian plate. SUBDUCTION ZONE :  Subduction Zone are the zones where subduction of plates occur. Obviously a sinkor a destructive boundary or a convergent boundary may be a subduction zone. Plunging stab or thesubducted plate is of oceanic crust. Buoyancy plays as important role in subduction zones. Back arebasins are the basins developed due to the subduction. Subduction zones are characterized by active  volcanism earthquake and the development of deep ocean trenches. The down-going stab is assimilatedin the mantle. However, partial melting of the oceanic crust of the subducted plate generates mafic igneousintrusion. The sepentinized pillow basalts and mafic intrusions with associated deep-sea sediments  occurring along with subduction zones is termed ophiolite suite. The zone where all kinds of earthquakes(shal-low, intermediate, and deep) originate is termed the Benioff zone or Benioff plane (named after hugoBenioff, and American Seismologist). Earthquakes are generated as the plate plunges creating frictionalforce. The Benioff zone is a thin inclined plane zone located on the top margin of the descending slab.  Benioff plane dips away from oceanic trenches and toward the adjacent island arcs and continents andmarks the surficial trace of the slippage of overriding and descending plates the subducted plate may bepartially melted and andesitic magma may be generated. Igneous activity, crustal deformation,mountain  building and metamorphism are associated with convergent boundaries. Partial fusion of oceanic crust that plunges in to the mantle generates granitic magma and continental in the roots of mountains. Sincesediments of low density accretes to the overriding plate, the plate grows and thus it become constructive.  Although the growth rate is 1 mm/year geologically it is significant. In the two plates of a destructive  boundary plate is constructed and the other destroyed. CONTINENTAL COLLISION : According to mattauer, intra-continental subduction can occur in three ways : 1.Crusts may be stacked one over the other; 2. Crust-mantle decollement may occur 3. Continental lithospheric subduction may also occur.  Collision of then Asian plate and Indian plate provides a best example for intra- continental subduction.

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 The results of the recent investigations on Himalayas reveal the occurrence of subduction of continental plates in contrast to the general belief that the continental crust cannot sink owing to it low density.  During initial periods of collision thickening of crust occurred along the boundary continued collision developed two strike slip faults between which a triangular northeast of India might have occupied a northern frontal location of Indian plate before collision.  As collision still persists the broken plate margins of both the plates plunge into the mantle. It is estimated that about 1500km of Indian continental lithosphere has disappeared into the mantle. The rates of subduction also vary with time.  During upper carboniferous period Indian plate moved at the rate of 10 cm per year. It was 5 cm per year in Eocene. But it moves 1 to 2 cm per year at present.

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UNIT II MINEROLOGY

Physical properties of minerals – Quartz group, Feldspar group, Pyroxene - hypersthene and augite, Amphibole – hornblende, Mica – muscovite and biotite, Calcite, Gypsum and Clay minerals.

Introduction About Mineralogy: It is a branch ofgeology, which deals with the various aspects related to minerals such as their individualproperties their mode of formation and mode of occurrence. It is defined as naturally occurring inorganic solid substance that is characterized with a definitechemical composition and very often with a definite atomic structure.

Their colour, streak, hardness, cleavage, crystal form, specific gravity and luste generally identify minerals. The symmetry elements are: i) Plane of symmetry ii) Axis of symmetry iii) Centre of Symmetry

physical properties : i) Colour ii) Lustre iii) Streak iv) Hardness v) Cleavage vi) Fracture vii) Tenacity viii) Structure ix) Specific gravity x) Form xi) Miscellaneous

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Color: Color is not constant in most of the minerals and commonly the color is due to stain or impurities in the minerals some minerals show peculiar phenomena connected with color. Play of colors: It is the development of a series of prismatic colors shown by some minerals or turning about in light. Change of colors: It is similar to play of colors that rate of change of colors on rotation is rather slow. Iridescene: Some minerals show rainbow colors either in their interior on the surface. This is termed iridescence. Streak:

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The streak, which is the color of the mineral powder, is more nearly constant than the color. The streak is determined by marking unglazed porcelain or simply by scratching it with a knife and observing the color of the powder. Lustre: It is the appearance of a fresh surface of a mineral in ordinary reflected light. The following are the important terms used to denote the lustre of minerals. Classy or vitreous lustre - Lustre like a broken glass Metallic lustre - When a mineral has lustre like metal. Pearly luster - Lustre like pearls Structure: This is a term used to denote the shape and form of minerals. The following are the important terms used to denote the structures of minerals. Columnar Structure - The mineral has a thick or thin column like Structures Bladed Structure - The mineral has blade like structure. Radiated structure - For columnar of fibrous diverging from central Points. Lamellar structure - The mineral made of separable plates. Botroidal structure - For an aggregate like bunch of grapes. Reniform structure - For kindney shaped aggregate. Hardness: It is the resistance of mineral offers to abrasion or scratching and is measured relative to a standard scale of ten minerals known as Moh’s scale of hardness. Hardness Name of the mineral 01 Talc 02 Gypsum 03 Calcite 04 Fluorite 05 Apatite 06 Orthoclase 07 Quartz The scale comprises ten minerals arranged to order of ascending hardness; the softest is assigned a value of 1 and the hardest value of 10. Hardness of any mineral will lie in between these twlimits. Specific gravity: It may be defined as the density of the mineral compared to the density of water and as such represents a ratio.ie specific gravity of a mineral is the ratio of its weight of an equal volume of water. Specific gravity of a mineral depends upon the weight and spacing of its atoms. Cleavage: It is defined as the tendency of a crystallized mineral to break along certain definite planes yielding more or less smooth surfaces. Cleavage is related to the internal structure of a mineral. The cleavage planes area always parallel to some faces of the crystal form typical mineral. It is also described on the basis of perfection or the degree of easiness with which minerals can split along the cleavage planes. Fracture:

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The fractures of a mineral may be defined as the appearance of its broken surface. Common types of fractures are: Conchodal fracture - The broken surfaces shows concentric rings Or curved surface. Even fracture - When the broken surface is smooth and flat. Uneven fracture - When the mineral breaks with an irregular Surface. It is a common fracture of many Minerals. Splintery structure - When the mineral breaks with a rough. Tenacity: Important properties related to tenacity of the minerals are expressed by the terms like balances, flexibility, elasticity, sectility and mellability etc. when a mineral can be cut with a knife it is termed “sectile” and if the slice cut out from it can be flattened under a hammer. It is also said “mellable” “brittle” minerals. Term elastic is used if it regains its former shape as the pressure is released. Form: The internal atomic arrangement of a mineral is manifested outwardly by development if geometrical shapes or crystal characters. The forms may be following three types: i crystallized – When the mineral occurs in the form of well defined crystals. ii Amorphous - When it shows absolutely no signs or evidence of crystallization. IiiCrystalline - when well-defined crystals are absent but a marked tendency Towards crystallization. Miscellaneous: Some of the special properties are mentioned below: Magnetism: Some minerals are highly magnetic,e,g magnetic, whereas few others may be feebly magnetic like spinals and tourmaline. Electricity: Some minerals an electric charge may be developed by heating in some others same effect results by applying pressure. Fluorescence:This term express property of some minerals to emit light when exposed to radiation. Phosphorescence: It is similar to fluorescence in essential character but in this case light is emitted not during the act of exposure to radiation but after the substance is transferred rapidly to dark place. i) Symmetry ii) Crystallographic axis Symmetry: Symmetry is understood a sort of regularity in the arrangement of faces on the body of a crystal. Symmetry is a property of fundamental importance for a crystal. It can be studied with reference to three different characters, commonly called elements of symmetry. These are: A plane of symmetry An axis of symmetry Centre of symmetry A plane of symmetry Any imaginary plane passing through the centre of a crystal in such a way that it divides the crystal in two exactly similar halves is called plane of symmetry. In other words, a plane of symmetry is said to exist in a crystal when for each face, edge or solid angle there is

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT anothersimilar face, edge or solid angle occupying identical position on the opposite side of this plane.

An axis of symmetry: It is defined as an imaginary line in a crystal passing through its centre in such a way that when a crystal is given a complete rotation along this line a certain cryatl face comes to occupy the same position at least twice. The nature of the axis of the symmetry into one of four types: Axis of Binary or twofold symmetry This requires that a crystal must be rotated by an angle of 180o to bring the reference face occupy the same position. Axis of Trigonal or threefold symmetry It is that axis on which a crystal must be rotated by an angle of 120o for a reference face to occupy the same position again in space. Axis of tetragonal or fourfold symmetry It is that axis on which the crystal must be rotated by an angle of 900 to bring a reference face in the same position in space. Axis of hexagonal or six fold symmetry: In which a rotation of 600 is required to fulfil the condition of repetition of reference face. Centre of symmetry A crystal said to possess a centre of symmetry if on passing an imaginary line from some definite face, edge or corner on one side of the crystal through its centre another exactly similar face or edge or corner is found on the other side at an equal distance from the centre. Ii) Crystallographic Axes These are also termed as axes of reference and are simply certain imaginary lines arbitrarily selected in such a way that all of them pass though centre of an ideal crystal. The concept of axes of reference is based on the fact that exact mathematical relations exist between all the faces on a given crystal with reference to its centre. In crystallography following general assumptions have been universally agreed upon regarding these crystallographic lines: a) Three Straight Lines, essentially passing though a common centre and varying in mutual relationships with respect to their lengths and angular inclinations from: all equal, Interchangable and it right to all unequal and inclined with each other. b) Four straight lines, essentially passing through a common centre; one vertical, being unequal to the other three but at right angles to them. The three horizontal axes are separated from each other at 1200 The concept of crystallographic axis has been the basis of classifying all, the crystallinesubstances into six crystal systems. i) Parameter ii) Indices iii) Symbols iv) Forms The numerical expression for such a relationship of a given crystal face with the crystallographicaxes is variously termed as Parameters, index or a symbol each term having its own significance. Parameters The relative intercepts made by a crystal face on the three crystallographic axes areknown as its parameters. For instance in the three crystallographic axes are represented byXOX’,YOY’ and

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ZOZ’. With their relative lengths as Ox=a, Oy=b and Oz= cLet us consider a face represented by a plane ijk occurring on this crystal. The intercepts of this plane with the three axes are oi, oj and ok. Which expressed in ters of the lengths of the axes is1a, 1/3b, 1/2c. Therefore 1a.1/3b and 1.2c are parameters of the face. These are generallyexpressed as parametrical ratios as 1a:1/3b:1/2c Indices In common practice the relationship of a crystal face with the crystallographic axes isexpressed in simple whole numbers, which are called indices. These indices are however alwaysbased on and derived from the parameters. There are a number of methods for deriving indicesfrom parameters such as the Neumann system and Miller system.In the miller system the indices for a given crystal face are derived from its parameters intwo simple steps:  By taking the reciprocals of the parameters actually obtained for the given face.  By clearing fractions if any by simplifications and omitting the letters for the axes  in the final expression. Symbol It is the simplest and most representative of the indices for a set of similar faces thatconstitute a crystallographic form. For instance in this fig there are six exactly identical crystalfaces, which have same mathematical relationship with all the three crystallographic axes.Obviously the six faces together make a form in which each face has an identical mathematicalrelationship with the three axes. This statement can also be mathematically written as 100 whichas generalization for all the six face of this particular form. FormsAny group of similar faces showing identical mathematical relations with crystallographic axes makes a form. Forms are further distinguished into following types:holohedral form hemihedral form, and hemomorphic form, enantimorphic form, andfundamental form, open and closed form. Holohedral form It is that form in a crystal system which shows development of all the possible faces in itsdomain. For instance, octahedron is a holohedral form because it shows all the eight facesdeveloped on the crystal; generally holohedral forms develop in the crystals of highest symmetryin a crystal system. Such class of highest symmetry in a system is called its normal class. Hemihedral form It shows as the name indicates only half the number of possible faces of a correspondingholhedral form of the normal class of the same system. As such all hemihedralforms may beassumed to have been derived form holohedral forms. The two complimentary hemihedral formswill necessarily embrace all the faces and characters of the parent holohedral form. Hemimorphic form It is also derived from a holohedral form and has only half the number of faces as inhemihedral form. In this case however all the faces of the form are developed only i-on oneextremity of the crystal. Being absent form the other extremity. In other words such a crystal willnot be symmetrical with reference to a centre of the symmetry. Enantiomorphous form It is composed of faces placed on two crystals of the same mineral in such a way thatfaces on one crystal become the mirror image of the form of faces on the other crystal. The formsand the corresponding crystal showing these forms are referred as left and right handed.

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Fundamental form It is also called a unit form. It designates that type of any given form in which theparametersessentially correspond to the unit lengths of the crystallographic axes. A form havinga symbol is essentially a fundamental form whereas another form also intercepting the three axesat different lengths. Open and closed forms A form is defined as closed when on full development it makes a fully enclosed solid. Inan open form space cannot be fully enclosed by it and entry from one or more sides is possible.

Elements Of The Symmetry And Minerals : i) Isometric system ii) Hexagonal system iii) Monoclinic system Isometric system: Definition: All those crystals that can be referred to three crystallographic axes, which are essentially equal in length at right angles to each other, and mutually interchangeable, are said to belong to the isomeric or cubic system. Axial diagram Since all the three axes are equal and interchangeable these are represented by the letter a. In the study position however the axes may be designated as a1,a2 and a3 the last being vertical. Classes Five symmetry classes fall in the Isometric system by virtue of their country The normal class is known as galena type. It has got the following symmetry. a) Axes of symmetry: 13 in all 3 are axes of four-fold symmetry 4 are axes of three-fold symmetry 6 are axes two fold of symmetry b) Planes of Symmetry: 9 in all 3 planes of symmetry are at right angles to each other and are termed the principal planes; 6 planes f symmetry are diagonal in position and bisect the angles between the principal planes. c) It has centre of symmetry. Forms Following are the forms that commonly develop in the crystals belonging to isometric system. 1. Cube: A form bounded by six similar square faces each of which is parallel to two of three crystallographic axes and meets the third axis. 2. Octahedron: A form bounded by eight similar faces each of the shape of an equilateral triangle each meeting the three crystallographic axes at equal distances. 3. Dodecahdraon: It is form with twelves similar faces each of which is parallel to one of the three crystallographic axes and meets the other two at equal distances. 4. Trisoctahedron: A form of twenty four faces; each face meeting two axes at unit length and to the third at greater that unity. 5. Trapezohedran: A forms of 24 faces each faces meeting one axes at unit length and to the other two at greater than unity. 6. Hexaoctahedran: 48 faces; each face meets the three axis at unequal distances.

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7. Tetra hexahedron: 24 faces each face meeting one axes and meet other to at unequal distance which are simple multiple of each other. Other classes: Isometric system comprises five symmetry classes in all. Beside the normal class following three classes are also represented among the minerals. 1. Pyritohedral Class a) Symmetry 7 axes of symmetry of which 3 are axial axesof two fold symmetry 4 are diagonal axes oftwo fold symmetry,3 planes of symmetry. Acentre of symmetry. b) Forms Pyritohedran and Diploid are two typical formsof this symmetry class.Diploid is a closed form of twenty-four facesthat typically occur in pairs. 2. Tetrahedral class a) Symmetry 7 axes of symmetry, 6 planes of symmetry diagonal, no centre symmetry. b) Forms Most typical form of this class is a four-sided solid in which each face is an equilateral triangle. It is termed tetrahedron. It has a general symbol. Hexagonal system All those crystals, which can be referred to four crystallographic axes of which i) Three axes are horizontal, equal, interchangeable and intersecting each other at 1200 between the positive ends. ii) The fourth axes are vertical and at right angles to the three horizontal axes are grouped under the hexagonal system. Axial diagram The horizontal axes all being equal are designated by the letter a(a1,a2,a3)and the vertical axis by the letter ‘c’ as usual. Forms Forms of hexagonal system differ in character from forms of all the other systems in that their parameters, indices and symbols are determined with respect to four crystallographic axes. Thus the general form expresses the relation of any hexagonal form. 1. Base: An open form of two faces in which each face meets the vertical axis only. 2. Prisms: A prism as defined earlier is an open form in which each face is essentially parallel to the vertical axis. Following three types of prisms are met with in the hexagonal system. a) Prism of 1st order. An open form of six faces in which each face is parallel to one of the three horizontal axes besides the vertical axis. It cuts the two horizontal axes at unit length. b) Prism of 2nd order. An open form of six faces like prism of 1st order but in this case each face cuts all the three horizontal axes, two axes at equal length and to the third at greater length. c) Prism of 3rd order: It is also called a dihexagonal prism as it has double the number of faces compared to the six faces of prism of 1st order. Monoclinic system The monoclinic system includes all those forms that can be referred to three crystallographic axes which are essentially unequal in length and further that can be of these is always inclined. Axial diagram All the three axes are unequal, they are designated by the letters a, b and c. The c axis is always vertical. The inclined axis is a- axis. It is inclined towards the observer and is also referred as clino axis.

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Normal class symmetry There are three symmetry classes placed in monoclinic system. The symmetry of the normal class is as given below: a) Axis of Symmetry 1 axis of two fold symmetry only b) Planes of symmetry 1 plane of symmetry only. And a centre of symmetry. The plane of symmetry is that plane which contains the crystallographic axes a and c Forms The common forms of this system are 1) Pinacoid it is an open from of two faces, each face being parallel to the two axes and cutting the third at a unit length .Three pinacoids are distinguished in the monoclinic system. i) a- pinacoid ii) b-pinacoid iii) c-pinacoid 2. Domes A dome is also form of two faces, each face meeting the vertical axis and one of the other two axes. It is a parallel to the third axis. Two types of domes are recognized: i) Orthodome ii) Clinodome 3. Prisms There are three types of prisms is there; i) Unit prism ii) Orthoprism iii) Clinoprism 4. Pyramid These are closed forms and in these each face meets all the three axes. i) Unit pyramid ii) Orthopyrmaid iii) Clinopyramid

Twinning and types of twin and common twin laws: A group of two crystals mutually united and intimately related are called TWINS and the phenomenon of their formation is called twinning. Terminology Terms commonly used in the explanation of twin Laws are: Twin plane, Twin axis, and composition plane. Twin plane: It is such a plane in a twin crystal, which is common to both the halves of the crystal and across which one half may appear to be the reflection of the other. Twin axis: It is a crystallographic direction along which a rotation of some degrees seems to have produced the resultant twins. The twin axis is other than the axis of two fold, four fold, and symmetry. Types of twins: The following types are: Contact Twins: In this type the component parts of a twin crystal are held together along a well defined composition plane.

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Penetration twins: In these twins the contact plane is not well defined. In fact the two parts of twin crystalmay appear to be inter penetrating to each other. Simple Twins: When a twin crystals has very well defined two halves held together according to easilyunderstanding relationships these may be said as simple twins. Common twin laws Following is a brief outline of the most commonly observed twin laws in differentcrystallographic system. Isometric system Spinal law: It is so named because of its presence in minerals of spinal group. In this law, octahedralface is the twin palce, which is also in most cases. Tetragonal system Rutile law The face of pyramid of IInd order is the twinning plane. This is the most common law for the crystals of the tetragonal system. Hexagonal system Brazilian Law: In this law the prism of IInd order is a twin plane. Quartz shows development of twinsaccording to this law. Dauphine law: In this law c-axis is the twinning axis. Twins are generally intergrown. Some quartz twinalso based on this law. Japanese law: Contact twins result on this law in which pyramid is a twinning plane. Orthorhombic system In this system, crystals show twinning in a variety of ways of which following are more common. a) When the prism angle is about 600 and the twinning is repeated. b) When the prism angle is 700 Staurolite Twinning. This mineral shows cruciform twins of two types. Right angled cross: These result when the face is a twinning plane Sea horse twin in which the face is a twin plane. In both cases the twins are of penetration type. Monoclinic system The following laws are the most common and in no case exclusive. Carlsbad law: The c-axis is the twinning axis. The minerals commonly show interpenetration or contact type of twinning. Baveno law: The mineral shows twining with clino dome as the twinning plane. Man Bach law: Here, the basal pinacoid is a twinning plane. Triclinic system Albite law

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

In this plane parallel to b-pinacoid is the twinning plane. Per cline law The twinning axis is easily defined as the one parallel to b-axis. The twins may be repeated polysynthetic type. classification and formation of coal: The term coal is generally applied to a sedimentary formation of highly carbonaceous character that is derived from vegetable matter involving set of process such as burial, compaction and biochemical transformation. Classification A number of classifications for coals are available of these the one most widely adopted is based on the rank of coal that defines degree of transformation of wood into coal through the natural processes of deposition, compaction and biochemical changes. Peat It is essentially a partly changed vegetable mater in the first stage of transformation to coal. The vegetable structure is easily visible and the evidence of its being in the processes of transformation. to coal. Peat is generally composed of remains of moss like plants but occasionally may contain reeds and partially altered portions of trees of higher order. Types: Two types of peat are commonly recognized:  Bog Peat, which is evolved out of lower type of vegetation, like mosses.  Mountain Peat that is decomposed and partially altered form of higher type’s of trees. Uses: Peat is a low value fuel in its application .It finds uses where available in abundance as i)Domestic fuel ii) gas purifier iii) For steam raising. Lignite It is a variously coloured variety of coal of lowest rank. In lignite transformation of vegetable matter to coal like material is almost complete. Fibrous texture is also shown by some lignite’s. Composition: Typical lignite has following composition: Fixed Carbon : 50 percent; oxygen 20-25 percent Hydrogen : 05 perecnt;nitrogen 02-05 percent Sulphur: 01-02 percent. Uses: These are used as domestic fuels and also in industry for distillation and gasification. This variety of coal has also been used in steam locomotives and for producing gas. Bituminous It is also known as the common coal,someties as coking coal and is ,in fact, the most common and important variety commercial coals. These are commonly black in colour, compactin structure breaking into almost cubical fragments when struck with hammer. They have a black streak. Bituminous coals burn freely leaving only a small mineral residue. Types and composition: The common bituminous coal is sometimes distinguished into three different types on the basis of its carbon content: sub-bituminous, bituminous and semi-bituminous coals. Anthracite It is a coal highest rank in which original organic source has been completely transformed into carbonaceous substance. It is very hard, jet black in colour, compact in structure and showing an almost metallic luster.

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

Uses: Anthracite is a favourite domestic fuel where available. It is also used for steam raising and other heating purposes. However because of its very low volatile matter content it is not suitable for making coke. Formation of coal There is absolutely no doubt regarding the nature of the source material form which coal is derived it is certainly always vegetable matter of one type or another. The two types of sources yielded vegetable material for the formation of the coal. i) The higher vegetation: It including herbs, shrubs and trees, growing on the plains, plateaus, sub-mountaineousand areas and characterized with wood tissue rich in cellulose and lignin and protein this type ofsource has been named as the humic sediment. ii) The lower vegetation: It comprising chiefly plank tonic algae, as soften found at the bottom of lakes and seas,submerged under water. This source has been named as sapropelic sediments.On the basis of place of accumulation of the source material, the environment could be distinguished as: Geosynclinal type: When accumulation took place in great sea basins characterized with considerable depth. Intermediate type: When deposition of source material took place along the sea shores at shallower depths. Platform type: Such as lagoons, lake basins and marshes and swamps. In these littoral environments decomposition of cellulose from humic organic matter is an easilyaccomplished process. IN other environment also the process may take the route of transport ofsource material its accumulation, compaction, dehyfdration and polymerisation to bituminouscoal to anthracite are all environment dependent. These are completed in an better manner ingeosynclinal situations that is under great depths in the presence of heat and pressure and seldom reach completion in littoral conditions. Summarisingly the transformation of organic source material into coal takes place due to:  Bio chemical decomposition which is achieved by certain type of bacteria and  involves breakdown of organic matter of wood into coal constituents.  Dynamo chemical transformation which involves alteration of original coal structure  into more compact, metamorphosed varieties chiefly under the influence of  temperature and pressure factors. FELSPAR GROUP: It is most abundant of all minerals It is used for making more than 50% by weight crust of earth It is non-metallic and silicate minerals

 CHEMICAL COMPOSITION: Potash feldspar KAlSi3 O8 Soda-lime feldspar NaAlSi3O8 (OR) CaAl2Si2O8 VARITIES OF POTASH FELSPAR: Orthoclase Sanidine Microcline SODA LIME FELSPAR: Albite Oligoclase Andecine Amarthitite Labrodorite  GENERAL PHYSICAL: CRYSTAL SYSTEM: monoclinic,triclinic HABIT: Tabular (crystalline) CLEAVAGE: Perfect( 2- directional) FRACTURE: Conchoidal or uneven COLOUR: White, grey, pink, green, red

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

LUSTRE: Vitreous HARDNESS: 6-6.5 SPECIFIC GRAVITY; 2.56-2.58(low) STREAK: No OCCURRENCE: Igneous rock USES: Ceramics, glass, tableware, enamels, electric porcelain, false teeth POTASH FELSPAR: ORTHOCLASE: CRYSTAL SYSTEM: monoclinic COLOUR: red CHEMICAL COMPOSITION: KAlSi3O8 MICROCLINE: CRYSTAL SYSTEM: triclinic COLOUR: flesh red CHEMICAL COMPOITION:KAlSi8 O8 USES: ceramic semiprecious SODA LIME FELSPAR: ALBITE: CRYSTAL SYSTEM: Triclinic COLOR: Whitish or pinkish white COMPOSITION: NaAlSi3 O8 USES: Ceramic, ornamental stone ANORTHITE: CRYSTAL SYSTEM: Triclinic COLOR: white COMPOSITION: Ca Al2Si2O8 (90%), NaAlSi3O8 (10%) USES: ceramic, ornamental stone  OCCURRENCE: all types of rocks  PYROXENES GROUP:  It is important group of rock forming minerals  They are commonly occur in dark colours, igneous and metamorphic rocks  They are rich in calcium, magnesium, iron, silicates  It show single chain structure of silicate  It is classified into orthopyroxene and clinopyroxene. It is based on internal atomic structure  ORTHOPYROXENE: Enstatite (MgSiO3) Hyperthene [(Mg,Fe)SiO3]  CLINOPYROXENE: Augite [(Ca, Na) (Mg, Fe, Al) (Al, Si)2O6]  Diopside [CaMgSi2O6] Hedenbergite[CaFeSi2O6]  AUGITE: CRYSTAL SYSTEM: Monoclinic  HABIT: Crystalline CLEAVAGE: Good ( primastic cleavage)  FRACTURE: Conchoidal  COLOUR: shades of greyish green and black  LUSTRE: vitreous  HARDNESS: 5-6  SPECIFIC GRAVITY: medium  STREAK: white  OCCURRENCE: ferro magnesium mineral of igneous rock (dolerite)  USES: rock forming mineral  COMPOSITON: [(Ca, Na) (Mg, Fe, Al) (Al, Si)2O6]  TRANSPARENCY: Translucent/opaque AMIPHOBLE GROUP: These are closely related to pyroxene group It shows double chain silicate structure  Rich in calcium, magnesium, iron oxide and Mn, Na, K and H CLASSIFICATION:  Orthorhombic  Monoclinic  Hornblende

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

 Tremolite  Actinolite

HORNBLENDE: (COMPOUND-COMPLEX SILICATE) CRYSTAL SYSTEM: Monoc;inic HABIT: crystalline CLEAVAGE: good(prismatic) FRACTURE: conchoidal COLOUR: dark green, dark brown black LUSTRE: vitreous HARDNESS: 5 to 6 SPECIFIC GRRAVITY: 3 to 3.5 (medium) STREAK: colourless or white COMPOSITION: hydrous silicates of Ca, Na, Mg, Al TRANSPARENCY: translucent/opaque OCCURRENCE: found in igneous rocks USES: road material MICA GROUP: Form sheet like structure Can be spilt into very thin sheets along one direction Aluminium and magnesium are rich Occupy 4% of earth crust Shows basal cleavage

CLASSIFICATION: LIGHT MICA:  Muscovite-KAL2(AlSi2O10)(OH)2-Potash mica  Paragonite-NaAl2(AlSi3O10)(OH)2-Soda mica  Lepidolite-KLiAl(Si4O10)(OH)2 –Lithium mica CLAY MINERAL GROUP:  These are phyllosilicates minerals  Essentially hydrous aluminium silicates  These are common weathering products  Very common in sedimentary rock

CLASSIFICATION: There are four group,  1. Kaolin a. Kaolinite b. Dictite c. Nacrite d. Halloysite 2. Smectite a. Montmorillonite b. Nontronite c. Hectorite 3. Illite 4. Chorite PHYSICAL PROPERTIES: KAOLIN GROUP: KAOLINITE: It is formed by weathering of aluminate- silicate minerals. The feldspar rick rocks are commonly weathered to kaolinite. Crystal system: Triclinic

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

Habit: Massive Colour: White sometimes brown Cleavage: Perfect Fracture: Even Streak: White Lustre: Dull earthy Hardness: 2 Specific gravity: 2.6(low) Transparency: Translucent Composition: Al2Si2O5(OH)4 Occurrence: secondary mineral formed by alternation of alkali feldspar Uses: ceramic industries, medicine, cosmetics and main components in porcelain HALLOYSITE: Crystal system: Monoclinic Habit: Massive ENGINEERING CONSIDERATIONS OF CLAY MINERALS: Montmorillonite is a dangerous type of clay cut it when found in road or tunnel since it hasexpandable nature which causes slope or wall failure

Kaolinite is used in ceramic industry , it is not expandable and wont absorb water

Clay is used as important material in construction industries both as building material and asfoundation or structure

It has poor drainage because the soil tends to stay wet and soggy when it is affected by water,while it is wet it can be easily compacted

It has poor aeration because the soil particles are small and closely spaced, it is very difficultfor air to enter or leave the soil

It has very high nutrients reserves, reducing the need for fertilization also because clayretains water plants growing in it often more drought tolerant than plants growing in sandy soil

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

UNIT III PETROLOGY

Classification of rocks, distinction between Igneous, Sedimentary and Metamorphic rocks.Engineering properties of rocks. Description, occurrence, engineering properties, distribution and uses of Granite, Dolerite, Basalt, Sandstone, Limestone, Laterite, Shale, Quartzite, Marble, Slate, Gneiss and Schist.

ROCKS:

 Defined as aggregates of minerals  Forms major part of earth crust  Quartzite and marbles contain only one mineral but most are composed of variety of different mineral

Classified Into 3 Groups. They Are

1. Igneous rocks

2. Sedimentary rocks

3. Metamorphic rocks

IGNEOUS ROCKS:

 Formed by cooling and solidification of magma  “Magma”is a hot viscous, siliceous melt, contains water vapour and gases  Magma comes from great depth bellow earth surface it composed of O, Si, Al,Fe, Mg, Na and K  When a magma comes out upon the earth surface such magma is called lava

CHEMICAL COMPOSITION: SiO2- 40-70% Al2O3- 10-20% Ca, Mg, Fe- 10% Magma are divided into 2 groups based on chemical composition ACID MAGMA: Si, Na and K(rich) Ca, Mg and Fe(poor) BASIC MAGMA: Ca, Mg and Fe (rich) Si, Na and K (poor) LIQUID PORTION: melt SOLIDS: any silicate minerals VOLATILES: dissolved gases in melt, including water vapour, CO2 and SO2 CRYSTALLIZATION OF MAGMA:  Cooling results in systematic arrangements of ions  Silicate minerals resulting in crystallization forms in a predictable order and develop distinct texture and structure

BASIC CLASSIFICATION: VOLCANIC ROCKS/ EXTRUSIVE ROCKS: Rocks formed from lava on earth surface PLUTONIC ROCKS/ INTRUSIVE ROCKS: Rocks formed from magm at deep seated layer in earth HYPABYSSAL ROCKS: Rocks formed close to surface of earth TEXTURE: Overall appearance of a rock based on the size, shape and arrangement of interlocking minerals is called texture.

TYPES OF IGNEOUS TEXTURE: BASED OF VISIBLE CRYSTALLINITY: APHANITIC:  Fine grained texture

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

 Rapid rate of cooling  Microscopic crystal  May contain visicles PHANERITIC:  Coarse grained texture  Slow cooling  Large, visible crystals GLASSY TEXTURE:  Very rapid cooling of lava  Resulting rock is called obsidian BASED ON VARIATION IN CRYSTAL SIZE: PORPHYRITIC TEXTURE: Large crystals (phenocrysts) are embedded in a matrix of smaller crystals ( ground mass) EQUIGRANULAR TEXTURE: All crystals are of same size INEQUIGRANULAR TEXTURE: Some of the crystals are larger than others BASED ON CRYSTAL SIZE: Coarse grained texture- crystal size >2mm Medium grained texture- crystal size 2-0.06 mm Fine grained texture- <0.06 mm OTHER TYPE OF TEXTURE: PEGMATITIC TEXTURE:  Coarse grained  Crystallization of granitic magma PYROCLASTIC TEXTURE:  Rock fragments thrown out during volcanic process are called pyroclastic.  Depending on size they are ash, lapilli and volcanic bombs Properties Of Rocks Structures and textures are physical features associated with the rocks. These occur along with theformation of rocks and are important in view of civil engineering point because  They contribute to the strength of rocks.  They contribute to the weakness of rocks  They reveal mode of origin of rocks. NOTE: The structures such as folds and faults are exempted though they are also structures since these develop after the formation of rocks due to tectonic forces. The term structure refers to certain large scale features  Vesicular structure:  Amygdaloidal structure  Columnar structure  Sheet structure  Flow structure VESICULAR STRUCTURE: This structure is due to porous in nature commonly observed in volcanicrocks. Most of the lava contains volatiles (gasses like CO2, water vapour) which escapes into theatmosphere by creating various sizes and shapes of cavities near the surface of lava flow. These cavitiesare called vesicles.Eg: SCORIA is a volcanic rock of highly porous.Eg: PUMICE, a light rock with porosity even that floats on water. AMYGDALOIDAL STRUCTURE: when secondary minerals such as calcite, zeolites, hydrated formsof silica (chalcedony, agate, amethyst, opal) are filled in vesicles, in such a case it is said Amygdaloidal structure. Eg: Deccan traps of India.( ie basalts). COLUMNAR STRUCTURE: with uniform cooling and contraction causes a regular or hexagonal form,which may be interested by cross- joints. Eg: Columnar basalts, around 40 mts high areseen at Andheri, Bombay. SHEET STRUCTURE: In this structure, the rocks appear to be made up of a number of sheets,

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT because of the development of horizontal cracks. When erosion takes place, the overlying stratagradually disappear and ultimately the plutonic rocks exposed to the surface resulting thedevelopment of joints / cracks parallel to the surface. Thus, the horizontal joint planes aresometimesso closely spaced as to produce a sheet structure. Eg: granite. FLOW STRUCTURE: After eruption of the lava flows, some of the bands or lines are drawnoverthe surface of lava to the direction of lava flow. Eg: Rhyolite.The texture of a rock refers to the individual mineral grains of size, shape, and mutual relations of mineralconstituentsand glassy matter in a rock. Depending on the nature of cooling, theTEXTURES inigneous rocks are categorized into: 1. Degree of crystallinity - Rocks composed entirely of crystals are called holocrystalline; thosecomposed entirely of glass are holohyalline; rocks that contain both crystals and glass arehypocrystalline / hemicrystalline . 2. Grain size - Overall, there is a distinction between the grain size of rocks that havecrystallized atdepth are medium to coarse grained (eg: gabbros) and those that crystallized at shallow deptharefiner grained (eg: basalts).Phaneric texture: if minerals in the rock are big enough to seen by the naked eye,the texture is said to be Phaneric. Eg: granite.Aphanitic texture: if mineralsare too fine to be seen the texture is said to be aphanitic.Eg:basalts. 3. Based on growth of crystals / Rock fabric - Fabric is the shape and mutual relationships among rock constituents: 1. Euhedral, refer to grains that are bounded by crystal faces by some crystal faces 3. Anhedral, when crystal faces are absent, it is called anhedral Hypidiomorphic / granular texture - the most common granular texture in which a mixture of euhedral,subhedral, and anhedral grains are present. Ophitic texture - is one where random plagioclase laths are enclosed by pyroxene or olivine. If plagioclaseis larger and encloses the ferromagnesian minerals, then the texture is subophitic . eg: basalt.Porphyritic texture: Large crystals that are surrounded by finer-grained matrix are referred to asphenocrysts. If the matrix or groundmass is glassy, then the rock has a vitrophyric texture. Poikilitic texture- Small euhedral crystals that are enclosed within a large mineral. Glassy Texture. The rock displays with sharp edges like broken glass is known as Glassy Texture. Noindividual crystals can be seen. Eg: obsidian.

GRANITE is a plutonic igneous rock, compact, massive and hard rock. Granites are unstratified butcharacterized by joints. It is a holocrystalline (completely crystalline) and leucocratic (light coloured)rock . Composition: Granite consists of quartz ( > 20 – 30 %), Feldspars (60%) include alkali feldspars (orthoclase, microcline) and plagioclase feldspars (oligoclase), micas as essential mineralsand accessory minerals are mafic minerals such as hornblende, biotite / muscovite , pyroxenes of hypersthenes; augite ; diopside ; magnetite / haematite, rutile, zircon, apatite, garnet..

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

Texture: Granites exhibit phaneric texture ( coarse grained ), or graphic texture (similar toArabicwriting ). Granites are usually equigranular but some times show inequigranular texture in case ofPorphyritic texture (feldspars occur as phenocrysts). Hand specimen: Granite is grayish or pinkish in color. Feldspar appears with white or brownish – red color. Quartz looks colorless. Biotite is jet black and is found as small shining flakes. Hornblende is dark greenish black. Varieties: When quartz decreases and increase in mafic minerals, granite passes over to GRANODIORITE and then DIORITE. When both the alkali feldspars and plagioclase feldspars are equal in quantity, the granite rock is called as ADAMELLITE. If hypersthene is more in granite then it is known as CHARNOCKITE. If feldspars and quartz are very large in size and exhibit interlocking texture, then it is called as PEGMATITE. Occurrence of large sized beryl, tourmaline crystals is another diagnostic feature ofpegmatite. RHYOLITE is very fined grained rock and is the volcanic equivalent of granite. When the accessory minerals present more in quantity than normally such rocks are named as eg; biotite- granite, hornblende-granite. Based on the color of feldspars, the granites are termed as Pink granite; grey granite. DOLERITE Dolerite is a dark, fine grained black or dark greenish black igneous rock. It is intermediate in composition and melanocratic (dark coloured) rock . Mineralogically and chemically, dolerite is similar to Gabbro and basalt. SPECIAL FEATURES: The compact nature and rich in mafic minerals make the rock emit metallicsound when hit with a hammer. Dolerite occurs in nature as an intrusive rock ie as dyke. ENGINEERING POINT OF VIEW: Dolerites are not common as building stones. They are suitable asroad metal, railway ballast, bitumen aggregate, concrete purposes. At foundation sites of dam like structures, the presence of dolerite is considered undesirable as they become a cause for weak planes. BASALT is a black volcanic, massive, fine grained, melanocratic rock. . COMPOSITION: Basalt consist of plagioclase feldspars ( labradorite), Pyroxenes (Augite) and iron oxides (magnetite or ilmenite). Biotite, hornblende and hypersthenes are the other accessory minerals.Pyrite may also seen sometimes. Either quartz or olivine may appear in small amounts depending on the silica content of parent lava. Structures & Textures: Vesicular and amygdaloidal structures are common in basalts. However, Columnar and flow structures are also observed in some cases. Basalts exhibit aphanitic texturein hand specimens. ( ie the minerals are too fine). Appearance in Hand specimens: Basalt is typically black or greenish grey or greenish black. Nonvesicular, massive in nature.

Engineering Properties Of Rocks: Field testing and, to a lesser extent, geophysical surveying are major sources of both qualititive andquantitative data relating to the ground conditions. In spite of the fact that in most cases field testing is more expensive to carry out than sampling and laboratory testing, it forms an essential part of many site investigations. There are several reasons for this, probably the most important of which is because it provides, for design purposes, parameters which represent a more realistic appraisal of geotechnical Two types of penetration tests are recognized (Anon 1975 and 1981). The standard penetration test (SPT) is a dynamic method in which a 51 mm external diameter split tube sampler connected to drilling rods, is driven into the ground by a series of hammer blows delivered at the surface. The test is conducted atintervals during the course of boring and it provides a distributed sample for identification purposes. In the static penetration

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT test a conical point is driven into the ground by means of a steady pressure on the top of the rods. Both tests provide an indirect measure of shear strength since the action of the tests produces a complex failure surface within the soil.Shear strength tests Various means of obtaining a direct indication of the in situ shear strength are available. Probably the most widely used of these is the shear vane test but brief reference will also be made to direct shear and triaxial tests. Shear vane test rotation of the vane and allowing a short period of time for pore pressures to dissipate. The test is used for very soft to firm, saturated, nonfissured, homogeneous clays. Plate loading tests

Mineralogical Composition, Texture, Engineering Properties And Uses Of Dolerite,Laterite, Sandstone And Limestone DOLERITE Dolerite is a dark, fine grained black or dark greenish black igneous rock. It is intermediate in composition and melanocratic (dark coloured) rock . Mineralogically and chemically, dolerite is similar to Gabbro and basalt. Composition: Dolerite consists of Plagioclase Feldspars and pyroxene (augite). Iron oxides, hypersthenes and biotite occur as common accessory minerals. Olivine is some times found if the parent magma was deficit of silica. Texture: Dolerite is a massive and compact rock. It is neither porous nor permeable. The texture in dolerites is generally equigranular. Interlocking texture is also common in dolerite. Under the microscope dolerite exhibit Ophitic or subophitic texture. Hand specimen: Dolerite is a fine grained rock with greenish black or black coloured. Presence of pyroxene (augite) contributes the black color of a rock. Feldspars can be observed by means of their cleavage surfaces and biotite if present appears as small, jet black.. Varieties: When all the minerals of dolerite are totally altered for eg: plagioclase into zoisite or epidote and augite into chlorite / hornblende and olivine into serpentine then the rock is called DIABASE. Plutonic equivalent of dolerite is called Gabbro. Volcanic equivalent of dolerite is called Basalt. Glassy equivalent of dolerite is called trachylyte. SPECIAL FEATURES: The compact nature and rich in mafic minerals make the rock emit metallic sound when hit with a hammer. Dolerite occurs in nature as an intrusive rock ie as dyke. ENGINEERING POINT OF VIEW: Dolerites are not common as building stones. They are suitable as road metal, railway ballast, bitumen aggregate, concrete purposes. At foundation sites of dam likestructures, the presence of dolerite is considered undesirable as they become a cause for weak planes. Sandstones Sandstones are abundant among sedimentary rocks but are next to shales. Sandstones are made up of sand and described as Arenaceous rocks. Sandstones are stratified and sometimes fossiliferous too. Compositionally, sandstones consist of sand grains ( 90% quartz ) with accessory minerals of such as mica, ilmenite, magnetite, garnet, zircon, rutile, feldspars cover the rest. In a hand specimen of sandstone, the size of sand grains may be coarse, medium or fine grained and other grains appear in different colors due to the presence of cementing material: Grains Appears as Quartz Colorless, fresh with vitreous luster Mica flakes White colour with perfect cleavage

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

Ilmenite / magnetite Jet black Garnet Red with shining Zircon; rutile White color with shining Feldspars Pale colours of brown, red, white, grey with a dull lustre Pyroxenes & amphiboles Pale colors Sandstones are generally porous and permeable and considered one of the best aquifers. By virtue of their porosity and permeability, they are not only capable of holding a good quantity of groundwater but also yield the same when tapped. LIMESTONES LIMESTONES: In hand specimens, limestones show different colours of white, gray, buff, cream, pink, yellow and black. In nature, limestones occur both as porous and massive types. On the otherhand, shell limestones care common and may be porous. Types of Limestones: Chalk: A soft, white fine grained calcareous deposit with dull lustre. It is also consists of fossils viz., foraminifera.Stalactites result from the process when surface water with dissolved calcium carbonate passthrough minute fractures and grows downwards from the roof of a cave. If the rate of percolation of solution is excess than required evaporation, the solution falls on floorand form as a cone like deposit which grows upwards from the floor is called as Stalagmites.If growth continues stalactites and stalagmites may come together after some time producing apillar like structure , called a DRIP STONE. Fossiliferous or Shell limestone: These are formed organically with hard parts of marine organisms of coral reefs or gasteropods or lamellibranchs or brachiopods etc. Engineering Properties And Uses Of Granite GRANITE is a plutonic igneous rock, compact, massive and hard rock. Granites are unstratified butcharacterized by joints. It is a holocrystalline (completely crystalline) and leucocratic (light coloured)rock .Composition: Granite consists of quartz ( > 20 – 30 %), Feldspars (60%) include alkali feldspars(orthoclase, microcline) and plagioclase feldspars (oligoclase), micas as essential mineralsand accessory minerals are mafic minerals such as hornblende, biotite / muscovite , pyroxenes ofhypersthenes; augite ; diopside ; magnetite / haematite, rutile, zircon, apatite, garnet.. Texture: Granites exhibit phaneric texture ( coarse grained ), or graphic texture (similar to Arabicwriting ). Granites are usually equigranular but some times show inequigranular texture in case of Porphyritic texture (feldspars occur as phenocrysts). Hand specimen: Granite is grayish or pinkish in color. Feldspar appears with white or brownish –red color. Quartz looks colorless. Biotite is jet black and is found as small shining flakes. Hornblende is dark greenish black.Varieties: When quartz decreases and increase in mafic minerals, granite passes over toGRANODIORITE and then DIORITE. When both the alkali feldspars and plagioclase feldspars are equal in quantity, the granite rock is called as ADAMELLITE. If hypersthene is more in granite then it is known as CHARNOCKITE. If feldspars and quartz are very large in size and exhibit interlocking texture, then it is called as PEGMATITE. Occurrence of large sized beryl, tourmaline crystals is another diagnostic feature of pegmatite. RHYOLITE is very fined grained rock and is the volcanic equivalent of granite. When the accessory minerals present more in quantity than normally such rocks are named as eg; biotite-granite, hornblende-granite. Based on the color of feldspars, the granites are termed as Pink granite; grey granite. SPECIAL FEATURES: Specific gravity of granite is 2.6 – 2.8

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

Density = 2500 – 2650 kg/cm3; compressive strength = 1000 – 2500 kg /sq cm

ENGINEERING POINT OF VIEW: By virtue of many desirable qualities, granite can be used infoundations of civil structures, building stone, road metal,. Tunneling through granite does not require any lining.

Igneous Rock, Metamorphic Rock And Sedimentary Rock On The Basis Of Structure And Texture

CLASSIFICATION OF IGNEOUS ROCKS:

Igneous rocks are the first formed rocks in the earth’s crust and hence these are called PRIMARY ROCKS, even though igneous rocks have formed subsequently also. Igneous rocks are the most abundant rocks in the earth crust and are formed at a very high temperature directly as a result of solidification of magma since magma is the parent material of igneous rocks. The temperature increases proportionately with the depth --- this is one of the reasons for the formation of igneous rocks. Igneous rocks are usually massive, unstratified, unfossiliferous and often occur as intrusive cutting across other rocks ( country rocks or host rocks ). The igneous rocks are classified based on silica%, silica saturation and depth of formation. METAMORPHIC ROCKS

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Igneous and sedimentary rocks which are formed under a certain physico-chemical environment, (theywere in equilibrium) in terms of temperature, pressure and chemically active fluids. Subsequent to theirformation if any of these factors changes, the existing equilibrium gets disturb in the constituent minerals ofparent rocks by metamorphism. As a result of Metamorphism  Granite changes to Granitic Gneiss  Peridotite (Ultrabasic) changes to Serpentine / Talc Schist.  Gabbro / Dunite changes to Hornblende Schist.  Sandstone changes to Quartzite.  Limestone changes into Marble.  Shale changes into Slate The process of metamorphism occuring in rocks due to the effect of high temperature, pressure andMchemically active fluids and are known as metamorphic agents. These three act together to causeMmetamorphism and sometimes any one or two of them dominate and play an active role.

Temperature: Metamorphic changes mainly take place in the temperature range of 350°C to 850°C.Pressure: Uniform pressure ( vertically downwards) increases with depth and effect on liquids and solidsat greater depths whereas the direct pressure (stress) due to tectonic forces acts in any direction i.e.,upwards, downwards and side wards and effect only on solids.

Chemically inactive fluids: The most common liquid is water. Also the magma or hot hydrothermalsolutions (containing various chemicals) may react directly with those rocks when they come in contact. Types of Metamorphism: 1. Thermal Metamorphism (Heat predominant)

2. Dynamic/Cataclastic Metamorphism: When direct pressure is predominant and acts, rocks are forcedto move past resisting in their crushing and granulation.

3. Geo-Thermal Metamorphism: Uniform pressure is predominant alongwith heat brings changes inoceanic salt deposits but not changes in silicate rocks.

4. Metasomatic Metamorphism (chemically active fluids predominant): This Metamorphism alters thecomposition of the rock significantly. Hydrothermal solutions are hot (upto 400°C) and cause forproviding new minerals such as Pb, Zn, Mn etc. Tourmaline, topaz and fluorspars are produced whenthe volatiles involved .Eg: When Granite is attacked by watervapour, Boron, fluorine will suffer mineralogical changes whereby feldspars replaced by tourmaline, the resultant rock may be Tourmaline Granite.

5. Dynamothermal Metamorphism: (Direct pressure and Heat pressure): When an argillaceous rock(shale) undergo Dynamo Thermal Metamorphism different minerals are produced. Eg. Gneisses andschists.Chlorite Biotite Garnet Staurolite Kyanite Sillimanite  The presence of chlorite and biotite in a metamorphic rock indicates that it had been formed under low  grade Metamorphism.  Presence of Garnet and Staurotite indicates medium grade of Metamorphism.  Occurrence of Kyanite and Sillimanite indicates high grade of Metamorphism.

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 Mineral Composition: Following are the common minerals found in metamorphic rocks: Cordite, Staurotite, Andaulusite; Sillimanite, Kyanite, idocrase formed during Metamorphism. Garnet,Chlorite, Talc, Epidote, Quartz, Feldspars, Pyroxenes, Calcite, Mica, Hornblende also occur in differentways due to Metamorphism.

FORMATION OF SEDIMENTARY ROCKS:

 Sedimentary rocks are formed by simple or complex mechanical or chemical processes.

 Biological activity is often involved in many cases in association with these processes. Sedimentary rocks are broadly grouped into three classes depending upon their mode of

 formation: clastic rocks (mechanically formed); chemically formed and organically formed sedimentary rocks.

 Mechanical weathering is the breakdown of rock into particles without producing changes in the  chemical composition of the minerals in the rock. Ice is the most important agent of mechanical weathering.

 Water percolates into cracks and fissures within the rock, freezes, and expands. The force exerted by the expansion is sufficient to widen cracks and break off pieces of rock. Heating and cooling of the rock, and the resulting expansion and contraction, also aids the process. Mechanical weathering contributesfurther to the breakdown of rock by increasing the surface area exposed to chemical agents.

 Chemical weathering is the breakdown of rock by chemical reaction. In this process the minerals within the rock are changed into particles that can be easily carried away. Air and water are both involved in many complex chemical reactions.

Outline the various Engineering properties of rocks: Field testing and, to a lesser extent, geophysical surveying are major sources of both qualitative and quantitative data relating to the ground conditions. In spite of the fact that in most cases field testing is more expensive to carry out than sampling and laboratory testing, it forms an essential part of many site investigations.

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 There are several reasons for this, probably the most important of which is because it provides, for design purposes, parameters which represent a more realistic appraisal of geotechnical Two types of penetration tests are recognized (Anon 1975 and 1981).

 The standard penetration test (SPT) is a dynamic method in which a 51 mm external diameter split tube sampler connected to drilling rods, is driven into the ground by a series of hammer blows delivered at the surface. The test is conducted at intervals during the course of boring and it provides a distributed sample for identification purposes. In the

 static penetration test a conical point is driven into the ground by means of a steady pressure on the top of the rods. Both tests provide an indirect measure of shear strength since the action of the tests produces aMcomplex failure surface within the soil. Shear strength tests  Various means of obtaining a direct indication of the in situ shear strength are available. Probably the most widely used of these is the shear vane test but brief reference will also be made to direct shear and triaxial tests.

 Shear vane test provide an indication of both peak and remoulded undrained shear strengths. Undrained shear strength is calculated from the relationship between torque and angular rotation, the vane dimensions and the maximum torque applied. Remoulded shear strength is measured similarly, after remoulding by rapid rotation of the vane and allowing a short period of time for pore pressures to dissipate.

 The test is used for very soft to firm, saturated, nonfissured, homogeneous clays. Plate loading tests

Mineral Composition, Texture, Origin, Engineering Properties And Uses (i)Granite (ii) Dolerite (i) GRANITE is a plutonic igneous rock, compact, massive and hard rock. Granites are unstratified butcharacterized by joints. It is a holocrystalline (completely crystalline) and leucocratic (light coloured)rock . Composition: Granite consists of quartz ( > 20 – 30 %), Feldspars (60%) include alkali feldspars (orthoclase, microcline) and plagioclase feldspars (oligoclase), micas as essential minerals and accessory minerals are mafic minerals such as hornblende, biotite / muscovite , pyroxenes of hypersthenes; augite ; diopside ; magnetite / haematite, rutile, zircon, apatite, garnet. Texture: Granites exhibit phaneric texture ( coarse grained ), or graphic texture (similar to Arabic writing ). Granites are usually equigranular but some times show inequigranular texture in case ofPorphyritic texture (feldspars occur as phenocrysts). Hand specimen: Granite is grayish or pinkish in color. Feldspar appears with white or brownish – red color. Quartz looks colorless. Biotite is jet black and is found as small shining flakes. Hornblende is dark greenish black. Varieties: When quartz decreases and increase in mafic minerals, granite passes over to GRANODIORITE and then DIORITE. When both the alkali feldspars and plagioclase feldspars are equal in quantity, the granite rock is

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT called as ADAMELLITE. If hypersthene is more in granite then it is known as CHARNOCKITE. If feldspars and quartz are very large in size and exhibit interlocking texture, then it is called as PEGMATITE. Occurrence of large sized beryl, tourmaline crystals is another diagnostic feature ofpegmatite. RHYOLITE is very fined grained rock and is the volcanic equivalent of granite. When the accessory minerals present more in quantity than normally such rocks are named as eg; biotite-granite, hornblende-granite. Based on the color of feldspars, the granites are termed as Pink granite; grey granite. SPECIAL FEATURES: Specific gravity of granite is 2.6 – 2.8 Density = 2500 – 2650 kg/cm3; compressive strength = 1000 – 2500 kg /sq cm ENGINEERING POINT OF VIEW: By virtue of many desirable qualities, granite can be used in foundations of civil structures, building stone, road metal,. Tunneling through granite does not require any lining. (ii) DOLERITE Dolerite is a dark, fine grained black or dark greenish black igneous rock. It is intermediate in composition and melanocratic (dark coloured) rock . Mineralogically and chemically, dolerite is similar toGabbro and basalt.Composition: Dolerite consists of Plagioclase Feldspars and pyroxene (augite). Iron oxides, hyperstheneand biotite occur as common accessory minerals. Olivine is some times found if the parent magmawas deficit of silica.Texture: Dolerite is a massive and compact rock. It is neither porous nor permeable. The texture indolerites is generally equigranular. Interlocking texture is also common in dolerite. Under themicroscope dolerite exhibit Ophitic or subophitic texture. Hand specimen: Dolerite is a fine grained rock with greenish black or black coloured. Presence ofpyroxene (augite) contributes the black color of a rock. Feldspars can be observed by means of their cleavage surfaces and biotite if present appears as small, jet black.. Varieties: When all the minerals of dolerite are totally altered for eg: plagioclase into zoisite or epidote and augite into chlorite / hornblende and olivine into serpentine then the rock is called DIABASE. Plutonic equivalent of dolerite is called Gabbro. Volcanic equivalent of dolerite is called Basalt. Glassy equivalent of dolerite is called trachylyte. SPECIAL FEATURES: The compact nature and rich in mafic minerals make the rock emit metallicsound when hit with a hammer. Dolerite occurs in nature as an intrusive rock ie as dyke. ENGINEERING POINT OF VIEW: Dolerites are not common as building stones. They are suitable asroad metal, railway ballast, bitumen aggregate, concrete purposes. At foundation sites of dam likestructures, the presence of dolerite is considered undesirable as they become a cause for weak planes.

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Quartz Granite Dolerite

Mineral Composition, Texture, Origin, Engineering Properties And Uses: BASALT is a black volcanic, massive, fine grained, melanocratic rock. COMPOSITION: Basalt consist of plagioclase feldspars ( labradorite), Pyroxenes (Augite) and ironoxides (magnetite or ilmenite). Biotite, hornblende and hypersthenes are the other accessory minerals.Pyrite may also seen sometimes. Either quartz or olivine may appear in small amounts dependingon the silica content of parent lava.Structures & Textures: Vesicular and amygdaloidal structures are common in basalts. However, Columnar and flow structures are also observed in some cases. Basalts exhibit aphanitic texture inhand specimens. ( ie the minerals are too fine). Appearance in Hand specimens: Basalt is typically black or greenish grey or greenish black. Nonvesicular,massive in nature. Exhibit a typical aphanitic texture ie extremely fine grained with or without vesicles. Basalts are always unstratified, unfossiliferous and do not react with acids. VESICULAR BASALT: it is characterized by the presence of empty cavities or vesicles. AMYGDALOIDAL BASALTS is a vesicular basalt with cavities filled up by secondary minerals ofsilica (quartz, amethyst, opal, agate); zeolites, calcite. Among these, silica minerals may be used assemi-precious gemstones. SPILLITE is a soda-rich basalt in which plagioclase feldspar is albite or oligoclase in stead of labradorite. Dolerite is the hypabyssal equivalent of basalt . Gabbro is plutonic equivalent of Basalt . Trachylite is equivalent of glassy basalt Alkali Basalt is unsaturated basalt Tholeite is oversaturated basalt Uses: Massive basalts are highly durable and strongest having highest load bearing capacity. Usedas building stones. Basalts are excellent for macadam and bitumen Roads. A number of tunnels have been made across through the Deccan traps for railway lines near Bombay.  They need no lining except sealing where the weak planes or joints are observed toprevent seepage.Rhyolite is an igneous, volcanic rock of felsic (silica-rich) composition (> 69% SiO2 ). It may have anytexture from glassy to aphanitic . The mineral assemblage is usually quartz, alkalifeldspar and plagioclase. Hornblende is a common accessory mineral.  Rhyolite can be considered as the extrusive equivalent to the plutonic granite rock, and consequently,outcrops of rhyolite may bear a resemblance to granite.

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 Rhyolites that cool too quickly to grow crystals form a natural glass or vitrophyre, also called obsidian.Slower cooling forms microscopic crystals in the lava and results in textures such as  flow foliations, spherulitic, nodular etc.. Some rhyolite is highly vesicular pumice..  Gabbro refers to a large group of dark, coarse-grained, intrusive mafic igneous rocks chemically equivalentto basalt. The rocks are plutonic, formed when molten magma is trapped beneath the Earth's surface and Cools into a crystalline mass.  The vast majority of the Earth's surface is underlain by gabbro within the oceanic crust, produced by basaltmagmatism at mid-ocean ridges.  Gabbro is dense, greenish colored and contains pyroxene, plagioclase, amphibole, and olivine (olivinegabbro when olivine is present in a large amount).  The pyroxene is mostly clinopyroxene; small amounts of orthopyroxene may be present. If the amount oforthopyroxene is substantially greater than the amount of clinopyroxene, the rock is thena norite. Quartz gabbros are also known to occur and are probably derived from magma that was oversaturatedwith silica.  Essexites represent gabbros whose parent magma was under-saturated with silica, resulting in theformation of the feldspathoid mineral nepheline. valuable amounts of chromium, nickel, cobalt, gold, silver, platinum,and copper sulfides.  Syenite is a coarse-grained intrusive igneous rock of the same general composition as granite but withthe quartz either absent or present in relatively small amounts (<5%).  Sandstones  Sandstones are abundant among sedimentary rocks but are next to shales. Sandstones are made  up of sand and described as Arenaceous rocks. Sandstones are stratified and sometimes  consist of sand grains ( 90% quartz ) with accessoryminerals of such as mica, ilmenite, magnetite, garnet, zircon, rutile, feldspars cover the rest

Clastic Rocks: These sedimentary rocks are formed through a number of steps. (a) Decay and disintegration: preexisting rocks everywhere on the surface of the earth are exposedto natural process of decay and disintegration like weathering and erosion. The original hard coherent rocksare loosened, decomposed in some cases and the grains and particles so obtained are transported toplaces of deposition (sea floor, lake basins and river channels). The disintegrated product is often calleddetritus. Hence, these rocks are also sometimes called detrital rocks. (b) Gradual deposition: the sediments as produced through weathering and erosion and transportedto depositional basin start settling there. Those sediments which are carried in suspension settle down onthe floor of the basin in accordance with their density, size and shape, forming layers. The particles thathave been transported in solution are first precipitated due to evaporation and then settle down. Depositiongenerally takes place under ordinary temperature and pressure conditions. (c) Compaction and consolidation - diagenesis: the sediments accumulate at first in the form of layers or heaps but gradually these get transformed into cohesive, hard and massive rocks when conditions are favorable. This process of transformation of loose particles into hard cohesive

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT rock- like masses is Called diagenesis. It may be achieved by either of the two methods: welding or cementation. Welding is the process of compaction and consolidation of the sediments accumulated in a basin due to pressure. Cementation is the process by which lose grains in a sedimentary deposit are held together by a foreign binding or cementing material. These binding substances are commonly supplied by percolatingwaters which are rich in carbonates of calcium and magnesium, oxides of iron and silicon, and clay. CHEMICALLY FORMED (NON_CLASSIC)ROCKS Water is a great solvent. Water from springs, streams, river, lakes and seas dissolves many compounds from the rocks with which it comes into contact. Under favorable conditions, a stage isreached when a part of this water may become saturated with one or more of the dissolved components. This may be followed by precipitation of salts as crystalline substances and their gradual accumulation inthe basin. The Rock Salt (NaCl) is formed more or less by this method. (c) ORGANICALLY FORMED (NON-CLASTIC) ROCKS: More than 70 per cent of the globe is covered by oceans and seas. These extensive and immense water bodies contain a variety of animal and plant life. The hard parts of many sea organisms are constituted chiefly of carbonates of calcium. Sediment Texture Clastic sediment textures have been described in previous modules (i.e. Advanced LoggingProceduresWorkbook), and a complete understanding is necessary for both cuttings sample and coredescriptions.This description will form the basis of all subsequent interpretation of the cuttings, the rock and theformation. The most commonly described clastic textures include: Grain Shape: Shape describes the geometric form of particles, which reflects the origin, history, andinternal lattice structure of the particles. Many times qualitative information on processes can be obtainedfrom the shape of particles. Particle shape is modified by abrasion during transport, being dependent upon; (1) initial shape when liberated from the source rock, (2) composition, (3) hardness, brittleness, ortoughness, (4) inherited partings, (5) size, (6) agent of transport, (7) rigors of transport, and (8) otherrandom effects. Grain Texture: Transport in running water does not significantly affect the shape of hard sand- sizeparticles. However, transport by water, wind, and glacial ice does affect the surface textures. Abrasioncreates pits, fractures and various surface markings reflect the origin of the particle. frameworkparticles, and the presence of any cementing agentm between the particles. The fabric is affected by themanner in which the particles were laid down and the resulting structure of the inter pore connections. Sphericity: The degree to which a particle approximates the shape of a sphere. This expresses how equalthe three mutually perpendicular dimensions of a particle are to one another. The rock type controls thesphericity. Porosity and Permeability When one discusses porosity and permeability in the oil fields, the primary concerns are the concepts ofabsolute and effective porosity. A reservoir will have a given amount of void space. If these voids are notconnected, production will be limited. Mudrocks

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Although sandstones and limestones are of primary concern in oil and gas exploration, the most abundantsediments are mudrocks (shales, claystones, etc.). These comprise about half of all the sediments. Mudrocks (Table 1-1) are deposited in practically every environment, with the primary environments ofdeposition being river floodplains, lakes, large deltas, the continental shelves and platforms, and the oceanfloors Another major type of clay mineral is the three layer group. These have sheetstructures composed oftwo layers of silica tetrahedra interleaved with aluminum di- and tri-octahedra. The most widely knownexamples are the smectite and illite groups. Sedimentary facies Sedimentary environments usually exist alongside each other in certain natural successions. A beach, where sand and gravel is deposited, will usually be bounded by a deeper marine environment a littleoffshore, where finer sediments are deposited at the same time. Behind the beach, there can be dunes(where the dominant deposition is well sorted sand) or a lagoon (where fine clay and organic material isdeposited). Every sedimentary environment has its own characteristic deposits. The typical rock formed ina certain environment is called its sedimentary facies. Sedimentary Structures Sedimentary structures are used to identify the agents of deposition and the resulting changes in that depositional environments that the sediments experienced after they were laid down). At the wellsite, one of the most important structure that can be recognized from cores and, at times, cuttings samples is the bedding type. Structures Of Sedimentary Rocks The terms structure includes some large scale features developed in the rocks during the process of their formation. These can be studied under following three headings. Mechanical structures These are the most prevalent structure includes some large scale features developed in the rocks during the process of their formation. These can be studied under following three specific types. Stratification: by stratification is understood a layered arrangement in a sedimentary rock. This may bedeveloped very prominently a can be seen from a distance or only slightly and may be detected after closeexamination. The different layers (also called beds or strata) may be of similar or similar or dissimilarcolour, grain size and composition. The beds are separated from each other by planes of weakness- thebending planes. Bedding Bedding is probably the most important feature of a sedimentary rock, and as such is the most widely used term in describing a sedimentary sequence. A “single bed” is generally described as a sedimentation unit which has been deposited under essentially constant physical conditions. 1. Regular or massive bedding 2. Laminated bedding 3. Graded bedding 4. Current or cross-bedding 5. Slump, or convolute bedding For example, regular bedding is indicated by parallel bedding surfaces; that is, those divisions in the lithology indicating a pause in the normal process of sedimentation. Between a given set of bedding surfaces, formations are normally uniform, indicating a constant source and transport of

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT sediments Another way of describing bedding is through analysis of the lithology's thickness and its lateral continuity. This allows the division of beds into four gross classifications:  Beds more or less equal in thickness.  Beds that are not equal in thickness and are laterally uniform and continuous.  Beds that are unequal in thickness, but still continuous.  Beds that are unequal in thickness and are laterally variable and discontinuous. Although there is no absolute correlation between bed thickness and grain size, there is a significant relationship. If you look at turbidites as a case in point, the further you go away from the suprafan channel, the finer the grains will be. This is primarily due to a significant drop in the energy available fortransportation. For this same reason, the overall thickness of those beds will be less. This relation of grainsize, bedding thickness, and energy (mode) of transport is true for most of the depositional processes. Thedip of the bedding surfaces is characteristic and structurally significant when recognized in a core sample inthe same way it is in a outcrop. Remember, the long axis of the core represents a section offormation cu parallel to the well bore and probably won't be vertical. Because the drill string will likely rotate during thecoring process, it is impossible to determine the actual strike of the bedding, unless the core was takenusing a specially oriented core barrel. Other than a bed's thickness and areal extent, the next significantfeatures that can be examined are the internal structures. Two major types of structures are recognized,cross bedding and graded bedding (Figure 2-2). These structures can be identified in most clastic rocks,regardless of the grain size. Cross bedding: it is a sedimentary structure in which layers lying one above another are not parallel butbear an irregular, inclined relationship. Such a structure results in shallow-water deposits when the stream. The structure is sometimes referred as false bedding orcurrent bedding. it is further distinguished into following types: (a) Tabular: a type of cross-bedding in which the top and bottom surfaces are essentially parallel but the intervening strata are inclined differently. (b) Lenticular: a type of cross-bedding in which the layers show extreme irregularity in their shape and disposition; each layer or set of beds may be intersected by many others lying at different angles. (c) Wedge shaped: in this case the structure is highly complex; there are sets of May layers bearing angular relationship. The layers in each set, however, are parallel to each other. The sets are inclined mutually in such a way that they give the appearance of interwoven wedges in vertical cross section. Graded bedding, or the progressional change in grain size throughout a bed's thickness, is very important to geologists in determining the original top and bottom of a bed as it was laid down. This is especially true in deep water turbidite deposits, where the gradation from coarse to fine sand, or an opposite These beds may range from several centimeters to more than a meter thick, and usually the thicker the graded bed, the coarser the sediments will be at the unit's base. Sometimes, the basal rock is composed of gravel. Graded beds are best described using a depositional model known as the “Bouma Cycle” (Figure 2-5). Bouma recognized during his study of turbidites that the “ideal” graded bed is composed of five basicparts: 1. Thelowest unit is definitely graded and is usually the thickest part of the sequence. 2. The second section commonly displays rippled cross lamination. 3. The third unit is composed of indistinctly laminated sandy or silty politic sediments.

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Mud cracks: these are common structural features of many fine-grained sedimentary rocks. These polygonal or irregular cracks are developed in drying muds. Subsequently, these cracked muds are covered by further layers of sediments but the cracked structure is preserved. Rain prints: these are marks (depressions of irregular, small crater-like shape) left on the top, dried surface of fine grained muds. Like mud cracks, these also get preserved when the particular layer is covered by subsequent deposits. Ripple marks: these are also common sedimentary structures of mechanical origin in deposits made in shallow waters. They are defined as symmetrical or unsymmetrical, wavelike undulations or irregularities in a layer. Ripple marks generally unsymmetrical, wavelike undulations or irregularities in a layer. Ripple marks generally result due to wind or wave action on the process of deposition. The fine sediments are dragged from their normal course by the waves developed in the water due to prevailing winds. Later on, these are deposited at places where the waves become weaker or die out. Bio-genic Sedimentary Structures Bio-genic structures result from bioturbation, the post-depositional disturbance of sediments by living organisms. This can occur by the organisms moving across the surface of sediment or burrowing into the first few centimeters. It is usually contemporaneous with deposition (Figure 2-10). The magnitude of the structures vary, from the surface trails left by large terrestrial vertebrates to burrows of small marine invertebrates.

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UNIT IV STRUCTURAL GEOLOGY AND GEOPHYSICAL METHODS

Geological maps – attitude of beds, study of structures – folds, faults and joints – relevance to civil engineering. Geophysical methods – Seismic and electrical methods for subsurface investigations.

STRUCTURAL FEATURES:

 Out crop  Strike  Dip

OUTCROP:

The rock exposure on the surface of the earth.

STRIKE: The trend of the rock bed on the ground surface is strike.

DIP:  The angle of inclination of a rock bed with the horizontal plane is called dip.  It measured in a plane perpendicular to the stripe line. There are two types of dip.

 True dip  Apparent dip.

TRUE DIP:  It is a perpendicular plane to the strike line.

APPARENT DIP:  It is a dip measured in any other direction than the true dip is called apparent dip.

FOLDS Investigation of dam site:

Preliminary investigation is done on the site to collect the information about the disadvantages or advantages of the site. This is more flexible because the detailed investigation will be more expensive,extensive and laborious. The important information collected at this stage is based on the factors asfollowed:

 Lithology  Structure  Physiography (Topography)  Ground water Conditions.

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Lithology provides the details of rocks types occurring in the dam site. The details include the types of rockpresent, their nature and extent of weathering, the occurrence of soil, rock debris, etc.

Lithology also givesa broad idea of the presence or absence of competent rocks, the weathering it has undergone and otherrelated information. The Structural study gives information on the strike and dip of the beds. It also reveals the occurrence ofgeological structures like folds, faults, joints, unconformities and foliation. Details of these features are veryimportant because they have a great influence on the suitability of site for dam.  Topography (Physiography) gives information about important surface features like valleys, hills, the trend of the river course, slopesand terraces present in the area.  These details indicate the stability of the slope and the slope of theoccurrence of landslides.  Topographic studies also help in rough assessment of the depth of the bedrock at the site. The nature of seismic activity in the region can also be known by suitable studies.  Groundwater conditions are related tothe study of occurrence of springs, seepages, swamps, wells etc. present in the selected area.  This type ofstudy indicates the water table position and the scope for leakage of water from the associated reservoir.  This also indicates the occurrence of solution cavities, if any, in the area. Detailed Investigation: If the Dam Sites is found to be good in the preliminary investigations,then it is take up for detailed investigation. This process comprises of surface and subsurface investigations. Surface investigations:  The surface investigations include closer examination of lithology, structure,physiography and groundwater conditions.  The thorough investigation of the above factors, with the support of laboratory studies of the materials at the dam site will reveal the conditions of outcrops, faults, joints,folds, & their attitudes, weathering details, soil occurrences, engineering properties like compressivestrength, tensile strength, porosity, permeability and durability.

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Subsurface investigations: These also include the factors of investigations as said above. But the studiesinclude the study of deeper layers of the dam site for ensuring the standards and safety of the dam. Tunnels: Tunnels are the underground passages or routes through hills, mountains or earth crust used for different purposes. These passages are made by excavating rocks below the surface or through the hills,mountains. Types of tunnels: Tunnels are basically made to serve some specific purposes. For instance: 1. Transportation tunnels: tunnels made across hills or high lands to lay roads or railwaytracks for regular traffic and transportation purpose. 2. Traffic tunnels: Tunnels laid to reduce the distancebetween places of interest across natural obstacles like hills, to save time and provide convenience arecalled traffic tunnels. These have the advantage of leaving the ground surface undisturbed so that it can be used as desired. 3. Diversion tunnels: The tunnels layed for diverting normal flow of river waterto keep the dam site dry are called diversion tunnels. 4. Pressure tunnels: these are also called as hydropower tunnels.These are used to allow water to pass through them under force, used for power generation. 5. Dischargetunnels: These are meant for conveying water from one point to another under gravity force, like across hill. 6. Public utility tunnels: These are the tunnels layed for public supplies like drinking water supply, cableslaying, sewage discharge or oil supply etc.

Effect of tunnelling on the ground:  Deterioration of the physical conditions of the ground is the commoneffect of tunnelling.  This happens because due to heavy and repeated blasting during excavatin, the rocksget shattered to a great extent and develop numerous cracks and fractures.  This reduces the cohesivenessand compactness of rocks.  At normal conditions the earth crust or underground rocks are under greatpreassre (overburden) or they will be in association with some geological structures like folding will be at equilibrium stress holding the previaling strain intact.  When the tunnel is created, such rocks which are atequilibrium gets distrubed resulting in the collapse of the roof. Freequent bursts may also occur.  Thisphenomenon of fall of rocks in brittle and hard rocks is called Popping. Due to tunnelling, the overlying Rocks deprive of support from the bottom and may become unstable. Such unstable conditions becomestill more precarious if the tunnelled beds are incompetent or loose or unconsolidated or saturated with ground water Lining of tunnels:

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 When tunnels are made through weak or loose or unconsolidated formations, they areprovided with suitable lining for safety and stability. Lining refers to the support porvided totunnel.  Lining may be in the form of steel structures or concrete. The main purposes of lining are to resist the pressuresfrom the surroundings and to protect the shape of tunnel. It takes care of the weaknesses of the ground.  It also helps in checking leakage of ground water into tunnel. The thickness of concrete lining dependes onthe extent of protection required, and the degree of weakness of the ground. It also depends on theoverbreak phenomenon. Lining is provided to support weakparts of the tunnel. Lining is also provided insuch places where the seepage of water into the tunnel occurs and creating problems.  In the case of veryweak rocks with unfavorable geological structures, lining may be necessary through out the length of the  tunnel.  The zones of faulting or shearing also need suitable lining to impart strength to them.  Overbreak:During tunneling the excavations normally involve the removal of extra rocks or matter around the tunnel.The quantity of rock broken and removed, in excess of what is required by the perimeter of the proposedtunnel, is known as overbreak. Factors governing the amout of overbreak: The nature of the rocks. The orientation and spacing of jointsor weak zones in them. In the case of sedimentary rocks, the orientation of the bedding planes  Thickness of the beds with respec to the alignment of the tunnel.  Geological factors influencing theoverbreak: Massive and soft rocks of a homogenous nature cause less overbreak than harder  rocks withwell developed joints or weak zones. In sedimentary rocks, thin formations and those with alternating hardand soft strata  produce more overbreak. This is because, during excavation, softer rocks yield more than  the hard rocks. Electrical Methods Used For Sub Surface Investigations. The electrical geophysical methods are used to determine the electrical resistivity of the earth's subsurface.Thus, electrical methods are employed for those applications in which a knowledge of resistivity or theresistivity distribution will solve or shed light on the problem at hand. The resolution, depth, and areal extentof investigation are functions of the particular electrical method employed.  Once resistivity data have beenacquired, the resistivity distribution of the subsurface can be interpreted in terms of soil characteristicsand/or rock type and geological structure. Resistivity data are usually integrated with other geophysicalresults and with surface and subsurface geological data to arrive at an interpretation.  Electrical methods can be broadly classified into two groups: those using a controlled (human-generated)energy source and those using naturally occurring electrical or electromagnetic energy as a source.  Thecontrolled source methods are most commonly used for shallow investigations, from characterizing surficialmaterials to investigating resistivities down to depths as great as 1 to 2 km, although greater depths ofinvestigation are possible with some techniques and under some conditions.

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

 The natural sourcemethodsare applicable from depths of tens of meters to great depths well beyond those of interest to hydrocarbondevelopment.  Possible applications of electrical methods for the development geologist range from the investigation ofsoil contaminants and the monitoring of enhanced oil recovery (EOR) projects to reservoir delineation andthe evaluation of geological stratigraphy and structure.  The application of electrical methods has beenprimarily confined to the onshore environment.  The offshore use of some techniques is possible,particularly for permafrost delineation and shallow marine geotechnical investigations.Electrical properties of materials  The application, interpretation, and understanding of electrical methods requires a familiarity with the relationship between soil and rock characteristics and the resistivities obtained from electrical data.  Theresistivity of subsurface rock formations is one of the physical properties determined through the process oflogging that is performed on most oil and gas wells, utilizing instrumentation inserted into the wellbore.  Theconcept of formation resistivity plays an important part in log analysis. Although there is a correlationbetween rock resistivities measured by well logs and those measured by electrical methods, the log is used to investigate properties only in the immediate vicinity of the wellbore while electrical methods yieldinformation on bulk properties averaged over a considerable volume of material.  The resistivity of most soils and rocks (including virtually all of the rocks of interest to hydrocarbonexploration) at the frequencies utilized by electrical methods is controlled by the fluids contained within therock[1] (see Determination of water resistivity).  This is because the dry soil or rock matrix is a virtualinsulator at DC and near DC frequencies. The pore fluid is in most cases water, with dissolved salts.  Thesalinity is the primary factor in determining the resistivity of the pore fluid, with pore configuration alsoplaying a part. Of lesser importance at oil reservoir depths is the temperature of the formation.  Oil and/or gas, when present, occur over such limited formation thicknesses that their effects on bulkaverageresistivity is, in most cases, undetectable.  Faulting or fracturing of porous sedimentary formations in most instances has little effect on the bulk average resistivity since the additional fracture porosity changes the already high porosity by only a smallpercentage.  However, in very tight rocks, such as igneous, metamorphic, and nonporous carbonate rocks,where intrinsic porosity is very low, the fluids in joints, cracks, and faulted zones may become the primaryconducting paths (see Porosity).  In summary, the factors affecting in situ average resistivity are the total porosity, including fault and fractureporosity, and the resistivity of the fluids present within the rock. The average resistivity can be considered  constant over the frequency range of interest to most of the methods under consideration here.Controlled source methodsControlled source methods use generated currents or electromagnetic fields as energy sources.  Anadvantage is the control over energy levels and the attendant positive effects on signal to noise ratio in areas of high cultural noise.

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

 A disadvantage of controlled source methods is that the complex nature of thesource field geometry (the geometry of the electromagnetic field or currents induced with the earth by thetransmitter) may present quantitative interpretation problems in areas of complex geology.In the DC method, a current (usually a very low frequency square wave and not actually direct current) isinjected into the earth through a pair of current electrodes, and the resulting potential field is mapped.  Various geometries of current and potential electrodes have been employed, with the choice primarilybased upon the depth and geometry of the survey target.  The measured surface potential field isinterpreted in terms of the subsurface resistivity distribution through modeling and inversiontechniques.  Induced polarization (IP) and complex resistivity (CR) techniques are special cases ofthe DC method in which the induced potential field is measured and interpreted in termsof mineralogy and/or soil characteristics.  IP and CR have been applied with some success to hydrocarbon  exploration through the measurement of geochemical alteration halos that have been found to be related toreservoirs under some conditions.  In the electromagnetic (EM) method, an electromagnetic field is produced on or above the surface of theground.  This primary EM field induces currents in subsurface conductors. The induced currents in turnreradiate secondary EM fields.  These secondary fields can be detected on or above the surface as either adistortion in the primary field (frequency domain methods) or as they decay following the turning off of theprimary field (time domain methods). Both loops and grounded wires are used to generate the source field.  Resistivities are calculated from the observed electromagnetic field data using modeling and inversiontechniques.EM techniques have been adapted to a variety of surface and airborne configuration, with the airborneinstruments generally limited in penetration to 100 to 200 m. Airborne electromagnetic surveys have provenvery effective for mapping the shallow resistivity distribution, leading to cost-effective surveys over largeareas.  Surface loop or grounded wire systems are applicable to depths well in excess of 1 km, althoughhigh power transmitters are required as depth increases.  The resolution attainable is normally consideredas a percentage of penetration depth, such that absolute resolution decreases with depth.In the controlled source magnetotelluric (CSMT) method, a low frequency electromagnetic wave isgenerated, and the electrical and magnetic fields are measured at some distance from the transmitter.  Thewave impedance of the electromagnetic wave at the receiver is calculated from the electrical and magneticfield values as a function of frequency and then interpreted in terms of the subsurface resistivity distribution.  Depths of penetration in excess of 1 to 2 km are attainable under suitable conditions.  Ground probing radar (GPR) is used for detailed investigations of the shallow subsurface. An extremelyshort pulse is generated and transmitted into the earth and reflections are received from interfaces betweenmaterials of differing resistivity and dielectrical constant.  GPR instrumentation is sophisticated but highlyportable.

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

 Depth of penetration is limited from less than 0.3 m in silty soils to over 100 m in permafrost,freshwater-saturated sand, and some very low porosity rocks. Successful applications include the  measurement of ice thickness, the location of cracks in ice, permafrost studies, the detailed mapping of thebedrock surface, the examination of soil stratification, and the mapping of contaminant plumes in theshallow subsurface.  An important application of GPR is locating buried pipes, tanks, and other objects thatreflect the radar pulse.  Natural source methodsNatural source methods take advantage of naturally occurring electrical potentials and electromagneticfields as energy sources.  Advantages of natural source methods are that there is no dependence on anartificial energy source and that the natural electromagnetic field is well understood.  The principaldisadvantages are the unpredictability and lack of control over energy levels and the attendant effects ofcultural noise on the signal to noise ratio.  The self-potential (SP) method examines the slowly varying surface potential field caused by  electrochemical and electrokinetic actions in near-surface materials.[4] Potentials can form, for example, atinterfaces between materials containing fluids with different ion contents, or they can be caused by movinggroundwater or by differential oxidation of ore bodies.  The method has been applied successfully ingeothermal and mineral exploration and in the delineation of certain groundwater contaminants. Fieldprocedures are straightforward, with the potential measured between carefully designed electrodes using  what is essentially a highly sensitive DC voltmeter. The potential field is mapped along profiles or on a gridof measurement stations. Interpretation is generally qualitative, with SP anomalies interpreted in terms ofthe shape and depth of the causative body or fluid flow. Magnetotellurics:  (MT) is an electrical method of geophysical exploration that makes use of naturallyoccurring electromagnetic energy propagating into the earth to determine the electrical resistivity of thesubsurface.  The low frequency electromagnetic field is measured, and the wave impedance iscalculated and expressed in terms of the resistivity of the subsurface.  The depth of investigation is afunction of the frequency of the electromagnetic wave, taking advantage of the fundamental principle that  the lower the frequency of a wave, the deeper the penetration into the crust. MT surveys generally involveapplications that range in depth from a few hundred meters to 10 km or more.  The resistivity versus depth cross section developed from MT data can be interpreted in terms of rock type.  Spatial variations in the resistivity-depth relationship observed at closely spaced locations on the surfacecan be interpreted in terms of subsurface geological structure.  While MT cannot be used to detect oildirectly, the identification of favorable rock types and the presence of geological structure capable oftrapping hydrocarbons is critical to successful exploration.  MT data are interpreted using forward andinverse modeling techniques. Resolution is considered low when compared with exploration or exploitationseismology, but may be adequate in certain instances to provide valuable information

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

concerninreservoirgeometry, rock characteristics, and a regional geological framework For the larger deep reservoirs, MT may be considered as a possible candidate for EOR monitoring if model studies indicatethat the resistivity changes over time associated with the operation are within the resolving power of themethod.Applications for development geology The following is a brief summary of some of the many possible applications of electrical methods of interestto the development geologist:  Evaluation of various characteristics of the shallow environment. Examples of such characteristics arethe classification of unconsolidated materials based on their electrical properties, the identification ofa lateral and/or vertical freshwater-saltwater boundary, the depth to bedrock, and the identification andmapping of conductive groundwater contaminants.  Monitoring of reservoir stimulation and enhanced recovery projects, where the stimulants and propants or flood materials can be expected to modify the resistivity of the formations.  Investigation of permafrost and ice characteristics in the Arctic.  Investigation of stratigraphy and structure, in particular as an adjunct to seismic data and in thoseareas where seismic data are poor or unreliable.  Seafloor geotechnical mapping, as an adjunct to high resolution seismic studies.

Folds In Rocks And Folds In The Design Of Dams And Tunnels: A geological fold occurs when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of permanent deformation. Synsedimentary folds arethose due to slumping of sedimentary material before it is lithified.

Folds in rocks vary in size frommicroscopic crinkles to mountain-sized folds. They occur singly as isolated folds and in extensive fold trainsof different sizes, on a variety of scales.Folds form under varied conditions of stress, hydrostaticpressure, pore pressure, and temperaturegradient, as evidenced by their presence in soft sediments, the full spectrum of metamorphic rocks, andeven as primary flow structures in some igneous rocks. A set of folds distributed on a regional scaleconstitutes a fold belt, a common feature of orogenic zones. Folds are commonly formed by shortening ofexisting layers, but may also be formed as a result of displacement on a non-planar fault (fault bend fold),at the tip of a

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT propagating fault (fault propagation fold), by differential compaction or due to the effects of ahigh-level igneous intrusion e.g. above a laccolith.Fold types  Anticline: linear, strata normally dip away from axial center, oldest strata in center irrespective oforientation.  Syncline: linear, strata normally dip toward axial center, youngest strata in center irrespective oforientation.  Antiform: linear, strata dip away from axial center, age unknown, or inverted.  Synform: linear, strata dip toward axial centre, age unknown, or inverted.  Dome: nonlinear, strata dip away from center in all directions, oldest strata in center.  Basin: nonlinear, strata dip toward center in all directions, youngest strata in center.  Monocline: linear, strata dip in one direction between horizontal layers on each side.  Chevron: angular fold with straight limbs and small hinges  Recumbent: linear, fold axial plane oriented at low angle resulting in overturned strata in one limb of  Slump: typically monoclinal, result of differential compaction or dissolution during sedimentation and lithification.  Ptygmatic: Folds are chaotic, random and disconnected. Typical of sedimentary slump  folding, migmatites and decollement detachment zones.  Parasitic: short wavelength folds formed within a larger wavelength fold structure - normally associatedwith differences in bed thickness  Disharmonic: Folds in adjacent layers with different wavelengths and shapes  (A homocline involves strata dipping in the same direction, though not necessarily any folding.) Causes of folding Folds appear on all scales, in all rock types, at all levels in the crust and arise from a variety of causes. Layer-parallel shortening  When a sequence of layered rocks is shortened parallel to its layering, this deformation may be accommodated in a number of ways, homogeneous shortening, reverse faulting or folding.  The responsedepends on the thickness of the mechanical layering and the contrast in properties between the layers. Ifthe layering does begin to fold,  The fold style is also dependent on these properties. Isolatedthick competent layers in a less competent matrix control the folding and typically generate classic roundedbuckle folds accommodated by deformation in the matrix.  In the case of regular alternations of layers ofcontrasting properties, such as sandstone- shale sequences, kink-bands, box-folds and chevron folds arenormally produced.Fault- related folding  Many folds are directly related to faults, associate with their propagation, displacement and the accommodation of strains between neighbouring faults.  Fault bend foldingFault bend folds are caused by displacement along a non-planar fault. In non-vertical faults, the hangingwalldeforms to accommodate the mismatch across the fault as displacement progresses.

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 Fault bend foldsoccur in both extensional and thrust faulting. In extension, listric faults form rollover anticlines in theirhanging walls.  In thrusting, ramp anticlines are formed whenever a thrust fault cuts up section from onedetachment level to another.  Displacement over this higher-angle ramp generates the folding.  Fault propagation foldingFault propagation folds or tip-line folds are caused when displacement occurs on an existing faultwithout further propagation.  In both reverse and normal faults this leads to folding of the overlying sequence, oftenin the form of a monoclineDetachment foldingWhen a thrust fault continues to displace above a planar detachment without further fault propagation, detachment folds may form, typically of box-fold style.  These generally occur above a gooddetachment such as in the Jura Mountains, where the detachment occurs on middle Triassicevaporites.Folding in shear zones  Shear zones that approximate to simple shear typically contain minor asymmetric folds, with the direction ofoverturning consistent with the overall shear sense.  Some of these folds have highly curved hinge lines andare referred to as sheath folds.  Folds in shear zones can be inherited, formed due to the orientation of preshearing layering or formed due to instability within the shear flow Folding in sediments

Recently deposited sediments are normally mechanically weak and prone to remobilisation before theybecome lithified, leading to folding. To distinguish them from folds of tectonic origin, such structures arecalled synsedimentary (formed during sedimentation). Slump folding: When slumps form in poorly consolidated sediments, they commonly undergo folding,particularly at their leading edges, during their emplacement. The asymmetry of the slump folds can beused to determine paleoslope directions in sequences of sedimentary rocks.

Dewatering: Rapid dewatering of sandy sediments, possibly triggered by seismic activity, can causeconvolute bedding.

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

Compaction:  Folds can be generated in a younger sequence by differential compaction over olderstructures such as fault blocks and reefs.  Igneous intrusionThe emplacement of igneous intrusions tends to deform the surrounding country rock.  In the case of highlevelintrusions, near the Earth's surface, this deformation is concentrated above the intrusion and oftentakes the form of folding, as with the upper surface of a laccolith.  Flow foldingThe compliance of rock layers is referred to as competence: a competent layer or bed of rock can withstandan applied load without collapsing and is relatively strong, while an incompetent layer is relatively weak.  When rock behaves as a fluid, as in the case of very weak rock such as rock salt, or any rock that is burieddeeply enough, it typically shows flow folding (also called passive folding, because little resistance isoffered): the strata appear shifted undistorted, assuming any shape impressed upon them by surroundingmore rigid rocks.  The strata simply serve as markers of the folding. Such folding is also a feature of manyigneous intrusions and glacier ice.

Electrical Methods About Sub Surface Features During Civil Engineering Investigations. The electrical geophysical methods are used to determine the electrical resistivity of the earth's subsurface.Thus, electrical methods are employed for those applications in which a knowledge of resistivity or theresistivity distribution will solve or shed light on the problem at hand. The resolution, depth, and areal extentof investigation are functions of the particular electrical method employed. Once resistivity data have beenacquired, the resistivity distribution of the subsurface can be interpreted in terms of soil characteristicsand/or rock type and geological structure. Resistivity data are usually integrated with other geophysicalresults and with surface and subsurface geological data to arrive at an interpretation. Electrical methods can be broadly classified into two groups: those using a controlled (human- generated)energy source and those using naturally occurring electrical or electromagnetic energy as a source.  Thecontrolled source methods are most commonly used for shallow investigations, from characterizing surficialmaterials to investigating resistivities down to depths as great as 1 to 2 km, although greater depths ofinvestigation are possible with some techniques and under some conditions.  The natural source methodsare applicable from depths of tens of meters to great depths well beyond those of interest to hydrocarbondevelopment.  Possible applications of electrical methods for the development geologist range from the investigation ofsoil contaminants and the monitoring of enhanced oil recovery (EOR) projects toreservoirdelineation andthe evaluation of geological stratigraphy and structure.  The application of electrical methods has beenprimarily confined to the onshore environment.  The offshore use of some techniques is possible, particularly for permafrost delineation and shallow marine geotechnical investigations.

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

Electrical properties of materials  The application, interpretation, and understanding of electrical methods requires a familiarity with therelationship between soil and rock characteristics and the resistivities obtained from electrical data. Theresistivity of subsurface rock formations is one of the physical properties determined through the process oflogging that is performed on most oil and gas wells, utilizing instrumentation inserted into the wellbore.  Theconcept of formation resistivity plays an important part in log analysis.  Although there is a correlationbetween rock resistivities measured by well logs and those measured by electrical methods, the log is usedto investigate properties only in the immediate vicinity of the wellbore while electrical methods yieldinformation on bulk properties averaged over a considerable volume of material.  The resistivity of most soils and rocks (including virtually all of the rocks of interest to hydrocarbonexploration) at the frequencies utilized by electrical methods is controlled by the fluids contained within therock (see Determination of water resistivity).  This is because the dry soil or rock matrix is a virtualinsulator at DC and near DC frequencies.  The pore fluid is in most cases water, with dissolved salts. Thesalinity is the primary factor in determining the resistivity of the pore fluid, with pore configuration alsoplaying a part.  Of lesser importance at oil reservoir depths is the temperature of the formation.  Oil and/orgas, when present, occur over such limited formation thicknesses that their effects on bulk averageresistivity is, in most cases, undetectable.  Faulting or fracturing of porous sedimentary formations in most instances has little effect on the bulkaverage resistivity since the additional fracture porosity changes the already high porosity by only a smallpercentage.  However, in very tight rocks, such as igneous, metamorphic, and nonporous carbonate rocks,where intrinsic porosity is very low, the fluids in joints, cracks, and faulted zones may become the primaryconducting paths (see Porosity).  In summary, the factors affecting in situ average resistivity are the total porosity, including fault and fractureporosity, and the resistivity of the fluids present within the rock.  The average resistivity can beconsidered onstant over the frequency range of interest to most of the methods under consideration here.

Controlled source methods  Controlled source methods use generated currents or electromagnetic fields as energy sources.  Anadvantage is the control over energy levels and the attendant positive effects on signal to noise ratio inareas of high cultural noise.  A disadvantage of controlled source methods is that the complex nature of thesource field geometry (the geometry of the electromagnetic field or currents induced with the earth by thetransmitter) may present quantitative interpretation problems in areas of complex geology.In the DC method, a current (usually a very low frequency square wave and not actually direct current) isinjected into the earth through a pair of current electrodes, and the resulting potential field is mapped.

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

 Various geometries of current and potential electrodes have been employed, with the choice primarilybased upon the depth and geometry of the survey target.  The measured surface potential field isinterpreted in terms of the subsurface resistivity distribution through modeling and inversiontechniques.  Induced polarization (IP) and complex resistivity (CR) techniques are special cases ofthe DC method in which the induced potential field is measured and interpreted in termsof mineralogy and/or soil characteristics.  IP and CR have been applied with some success to hydrocarbonexploration through the measurement of geochemical alteration halos that have been found to be related toreservoirs under some conditions.  In the electromagnetic (EM) method, an electromagnetic field is produced on or above the surface of theground.  This primary EM field induces currents in subsurface conductors. The induced currents in turnreradiate secondary EM fields. These secondary fields can be detected on or above the surface as either adistortion in the primary field (frequency domain methods) or as they decay following the turning off of theprimary field (time domain methods). Both loops and grounded wires are used to generate the source field.  Resistivities are calculated from the observed electromagnetic field data using modeling andinversiontechniques.  EM techniques have been adapted to a variety of surface and airborne configuration, with the airborneinstruments generally limited in penetration to 100 to 200 m.  Ground probing radar (GPR) is used for detailed investigations of the shallow subsurface. An extremelyshort pulse is generated and transmitted into the earth and reflections are received from interfaces betweenmaterials of differing resistivity and dielectrical constant. GPR instrumentation is sophisticated but highlyportable.  Depth of penetration is limited from less than 0.3 m in silty soils to over 100 m in permafrost,freshwater-saturated sand, and some very low porosity rocks. Successful applications include the  measurement of ice thickness, the location of cracks in ice, permafrost studies, the detailed mapping of thebedrock surface, the examination of soil stratification, and the mapping of contaminant plumes in theshallow subsurface. An important application of GPR is locating buried pipes, tanks, and other objects thatreflect the radar pulse. Natural source methods  Natural source methods take advantage of naturally occurring electrical potentials and electromagneticfields as energy sources.  Advantages of natural source methods are that there is no dependence on anartificial energy source and that the natural electromagnetic field is well understood.  The principaldisadvantages are the unpredictability and lack of control over energy levels and the attendant effects ofcultural noise on the signal to noise ratio.The self-potential (SP) method examines the slowly varying surface potential field caused by  electrochemical and electrokinetic actions in near-surface materials.  Potentials can form, for example, atinterfaces between materials containing fluids with different ion contents, or they can be caused by movinggroundwater or by differential oxidation of ore bodies.

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

 The method has been applied successfully ingeothermal and mineral exploration and in the delineation of certain groundwater contaminants.  Fieldprocedures are straightforward, with the potential measured between carefully designed electrodes usingwhat is essentially a highly sensitive DC voltmeter.  The potential field is mapped along profiles or on a gridof measurement stations.  Interpretation is generally qualitative, with SP anomalies interpreted in terms ofthe shape and depth of the causative body or fluid flow.  Magnetotellurics (MT) is an electrical method of geophysical exploration that makes use of naturallyoccurring electromagnetic energy propagating into the earth to determine the electrical resistivity of thesubsurface.  The low frequency electromagnetic field is measured, and the wave impedance iscalculated and expressed in terms of the resistivity of the subsurface.  The depth of investigation is afunction of the frequency of the electromagnetic wave, taking advantage of the fundamental principle thatthe lower the frequency of a wave, the deeper the penetration into the crust.  MT surveys generally involveapplications that range in depth from a few hundred meters to 10 km or more.  The resistivity versus depth cross section developed from MT data can be interpreted in terms of rock type.Spatial variations in the resistivity-depth relationship observed at closely spaced locations on the surfacecan be interpreted in terms of subsurface geological structure.  While MT cannot be used to detect oildirectly, the identification of favorable rock types and the presence of geological structure capable oftrapping hydrocarbons is critical to successful exploration.  MT data are interpreted using forward andinverse modeling techniques. Resolution is considered low when compared with exploration or exploitationseismology, but may be adequate in certain instances to provide valuable information concerning reservoirgeometry, rock characteristics, and a regional geological framework.  For the larger deep reservoirs, MT may be considered as a possible candidate for EOR monitoring if model studies indicatethat the resistivity changes over time associated with the operation are within the resolving power of themethod.Applications for development geology The following is a brief summary of some of the many possible applications of electrical methods of interestto the development geologist:  Evaluation of various characteristics of the shallow environment. Examples of such characteristics arethe classification of unconsolidated materials based on their electrical properties, the identification ofa lateral and/or vertical freshwater-saltwater boundary, the depth to bedrock, and the identification andmapping of conductive groundwater contaminants.  Monitoring of reservoir stimulation and enhanced recovery projects, where the stimulants and propantsor flood materials can be expected to modify the resistivity of the formations.  Investigation of permafrost and ice characteristics in the Arctic.  Investigation of stratigraphy and structure, in particular as an adjunct to seismic data and in thoseareas where seismic data are poor or unreliable.

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

 Seafloor geotechnical mapping, as an adjunct to high resolution seismic studies.

Gravity Method In Geophysics:  For human exploration of the solar system, instruments must meet criteria of low mass, low volume, lowpower demand, safe operation, and ruggedness and reliability (Meyer et al., 1995; Hoffman, 1997; Budden,1999).  Tools used for planetary exploration will need to address fundamental scientific questions andidentify precious resources, such as water.  The primary goal of studying detailed gravity data is to provide a better understanding of the subsurfacegeology.  The gravity method is a relatively cheap, non-invasive, non-destructive remote sensing methodthat has already been tested on the lunar surface.  It is also passive – that is, no energy need be put into theground in order to acquire data; thus, the method is well suited to a populated setting such as Taos, and aremote setting such as Mars.  The small portable instrument also permits walking traverses – ideal, in viewof the congested tourist traffic in Taos.  Measurements of gravity provide information about densities of rocks underground.  There is a wide rangein density among rock types, and therefore geologists can make inferences about the distribution of strata.In the Taos Valley  we are attempting to map subsurface faults.  Because faults commonly juxtapose rocks of differing densities, the gravity method is an excellent exploration choice.  This is a generalized summary of the types of corrections that we have applied to the Taosgravity data The Gal (for Galileo) is the cgs unit for acceleration where one Gal equals 1 centimenter per second squared. Because variations in gravity are very small, units for gravity surveys are generally in milligals (mGal) where 1 mGal is one thousandth of 1cm/s2. Standard gravity ( gnor g0 ) is taken as the freefall accelleration of an object at sea level at a latitude of 45.5° and is 980.665 cm/s2 (or equivalently 9.80665 m/s2). Standard gravity is therefore 980.665 Gal or 980665 mGal. It is useful to remember that 1 mGal is just a bit more than 1 millionth of gn (1.01972 x 10-6 gn). Observed Gravity (gobs ) - Gravity readings observed at each gravity station after corrections have been applied for instrument drift and earth tides. Latitude Correction (gn ) - Correction subtracted from gobs that accounts for Earth's elliptical shape and rotation. The gravity value that would be observed if Earth were a perfect (no geologic or topographic complexities), rotating ellipsoid is referred to as the normal gravity.gn = 978031.85 (1.0 + 0.005278895 sin2(lat) + 0.000023462 sin4(lat)) (mGal) where lat is latitude Free Air Corrected Gravity (gfa ) - The free-air correction accounts for gravity variations causedby elevation differences in the observation locations. The form of the Free-Air gravity anomaly, gfa ,is given by: gfa = gobs - gn+ 0.3086h (mGal) where h is the elevation (in meters) at which the gravity station is above the datum (typically sea level).

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Bouguer Slab Corrected Gravity (gb ) - The Bouguer correction is a first-order correction to account for the excess mass underlying observation points located at elevations higher than theelevation datum (sea level or the geoid). Conversely, it accounts for a mass deficiency at observation points located below the elevation datum. The form of the Bouguer gravityanomaly, gb, is given by: gb = gobs - gn + 0.3086h - 0.04193r h (mGal) where r is the average density of the rocks underlying the survey area. Terrain Corrected Bouguer Gravity (gt ) - The Terrain correction accounts for variations in theobserved gravitational acceleration caused by variations in topography near each observation point. Because of the assumptions made during the Bouguer Slab correction, the terrain correctionis positive regardless of whether the local topography consists of a mountain or a valley. The formof the Terrain corrected, Bouguer gravity anomaly, gt , is given by: gt = gobs - gn + 0.3086h - 0.04193r h + TC (mGal) where TC is the value of the computed Terrain correction. Assuming these corrections have accurately accounted for the variations in gravitational acceleration theywere intended to account for, any remaining variations in the gravitational acceleration associated with theTerrain Corrected Bouguer Gravity can be assumed to be caused by geologic structure.

FAULTS: A geological fold occurs when one or a stack of originally flat and planar surfaces, suchas sedimentary strata, are bent or curved as a result of permanent deformation. Synsedimentary folds arethose due to slumping of sedimentary material before it is lithified. Folds in rocks vary in size frommicroscopic crinkles to mountain-sized folds. They occur singly as isolated folds and in extensive fold trainsof different sizes, on a variety of scales.Folds form under varied conditions of stress, hydrostatic pressure, pore pressure, and temperaturegradient, as evidenced by their presence in soft sediments, the full spectrum of metamorphic rocks, andeven as primary flow structures in some igneous rocks. A set of folds distributed on a regional scaleconstitutes a fold belt, a common feature of orogenic zones. Folds are commonly formed by shortening ofexisting layers, but may also be formed as a result of displacement on a non-planar fault (fault bend fold),at the tip of a propagating fault (fault propagation fold), by differential compaction or due to the effects of ahigh-level igneous intrusion e.g. above a laccolith. Fold types Anticline: linear, strata normally dip away from axial center, oldest strata in center irrespective of orientation.  Syncline: linear, strata normally dip toward axial center, youngest strata in center irrespective of orientation.  Antiform: linear, strata dip away from axial center, age unknown, or inverted.  Synform: linear, strata dip toward axial centre, age unknown, or inverted.  Dome: nonlinear, strata dip away from center in all directions, oldest strata in center.  Basin: nonlinear, strata dip toward center in all directions, youngest strata in center.  Monocline: linear, strata dip in one direction between horizontal layers on each side.  Chevron: angular fold with straight limbs and small hinges  Recumbent: linear, fold axial plane oriented at low angle resulting in overturned strata in one limb

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

Slump:  typically monoclinal, result of differential compaction or dissolution during sedimentation and lithification.  Ptygmatic: Folds are chaotic, random and disconnected. Typical of sedimentary slump  folding, migmatites and decollement detachment zones.  Parasitic: short wavelength folds formed within a larger wavelength fold structure - normally associated  with differences in bed thickness  Disharmonic: Folds in adjacent layers with different wavelengths and shapes  (A homocline involves strata dipping in the same direction, though not necessarily any folding.) Causes Of Folding Folds appear on all scales, in all rock types, at all levels in the crust and arise from a variety of causes. Layer-parallel shortening  When a sequence of layered rocks is shortened parallel to its layering, this deformation may be accommodated in a number of ways, homogeneous shortening, reverse faulting or folding.  The responsedepends on the thickness of the mechanical layering and the contrast in properties between the layers.  If the layering does begin to fold, the fold style is also dependent on these properties. Isolatedthick competent layers in a less competent matrix control the folding and typically generate classic roundedbuckle folds accommodated by deformation in the matrix.  In the case of regular alternations of layers ofcontrasting properties, such as sandstone- shale sequences, kink-bands, box-folds and chevron folds arenormally produced.Fault- related foldingMany folds are directly related to faults, associate with their propagation, displacement and the accommodation of strains between neighbouring faults.Fault bend folding Fault bend folds are caused by displacement along a non-planar fault. In non- vertical faults,  The hangingwalldeforms to accommodate the mismatch across the fault as displacement progresses. Fault bend foldsoccur in both extensional and thrust faulting. In extension, listric faults form rollover anticlines in theirhanging walls.  In thrusting, ramp anticlines are formed whenever a thrust fault cuts up section from onedetachment level to another.  Displacement over this higher-angle ramp generates the folding.Fault propagation foldingFault propagation folds or tip-line folds are caused when displacement occurs on an existing fault withoutfurther propagation.  In both reverse and normal faults this leads to folding of the overlying sequence, oftenin the form of a monoclineDetachment foldingWhen a thrust fault continues to displace above a planar detachment without further faultpropagation, detachment folds may form, typically of box-fold style.  These generally occur above a gooddetachment such as in the Jura Mountains, where the detachment occurs on middle Triassicevaporites.Folding in shear zonesShear zones that approximate to simple shear typically contain minor asymmetric folds, with the direction ofoverturning consistent with the overall shear sense.

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 Some of these folds have highly curved hinge lines andare referred to as sheath folds. Folds in shear zones can be inherited, formed due to the orientation of preshearinglayering or formed due to instability within the shear flowFolding in sedimentsRecently deposited sediments are normally mechanically weak and prone to remobilisation before theybecome lithified, leading to folding. To distinguish them from folds of tectonic origin, such structures arecalled synsedimentary (formed during sedimentation).  Slump folding: When slumps form in poorly consolidated sediments, they commonly undergo folding,particularly at their leading edges, during their emplacement.  The asymmetry of the slump folds can beused to determine paleoslope directions in sequences of sedimentary rocks.  Dewatering: Rapid dewatering of sandy sediments, possibly triggered by seismic activity, can causeconvolute bedding.Compaction:  Folds can be generated in a younger sequence by differential compaction over older structures such as fault blocks and reefs. Igneous intrusionThe emplacement of igneous intrusions tends to deform the surrounding country rock.  In the case of highlevelintrusions, near the Earth's surface, this deformation is concentrated above the intrusion and oftentakes the form of folding, as with the upper surface of a laccolith.  Flow foldingThe compliance of rock layers is referred to as competence: a competent layer or bed of rock can withstandan applied load without collapsing and is relatively strong, while an incompetent layer is relatively weak.  When rock behaves as a fluid, as in the case of very weak rock such as rock salt, or any rock that is burieddeeply enough, it typically shows flow folding (also called passive folding, because little resistance isoffered): the strata appear shifted undistorted, assuming any shape impressed upon them by surroundingmore rigid rocks.  The strata simply serve as markers of the folding. Such folding is also a feature of manyigneous intrusions and glacier ice. Types Of Faults And Their Influence On Dams And Tunnels:  A geological fold occurs when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of permanent deformation.  Synsedimentary folds arethose due to slumping of sedimentary material before it is lithified.  Folds in rocks vary in size frommicroscopic crinkles to mountain-sized folds. They occur singly as isolated folds and in extensive fold trains of different sizes, on a variety of scales.  Folds form under varied conditions of stress, hydrostatic pressure, pore pressure, and temperaturegradient, as evidenced by their presence in soft sediments, the full spectrum of metamorphic rocks, andeven as primary flow structures in some igneous rocks.  A set of folds distributed on a regional scaleconstitutes a fold belt, a common feature of orogenic zones.  Folds are commonly formed by shortening ofexisting layers, but may also be formed as a result of displacement on a non-planar fault (fault bend fold),at the tip of a propagating fault (fault propagation fold), by differential compaction or due to the effects of ahigh- level igneous intrusion e.g. above a laccolith. Fold types

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 Anticline: linear, strata normally dip away from axial center, oldest strata in center irrespective of orientation.  Syncline: linear, strata normally dip toward axial center, youngest strata in center irrespective of orientation.  Antiform: linear, strata dip away from axial center, age unknown, or inverted.  Synform: linear, strata dip toward axial centre, age unknown, or inverted.  Dome: nonlinear, strata dip away from center in all directions, oldest strata in center.  Basin: nonlinear, strata dip toward center in all directions, youngest strata in center.  Monocline: linear, strata dip in one direction between horizontal layers on each side.  Chevron: angular fold with straight limbs and small hinges  Recumbent: linear, fold axial plane oriented at low angle resulting in overturned strata in one limb of the fold.  Slump: typically monoclinal, result of differential compaction or dissolution during sedimentation and lithification.  Ptygmatic: Folds are chaotic, random and disconnected. Typical of sedimentary slump  folding, migmatites and decollement detachment zones.  Parasitic: short wavelength folds formed within a larger wavelength fold structure - normally associated with differences in bed thickness  Disharmonic: Folds in adjacent layers with different wavelengths and shapes (A homocline involves strata dipping in the same direction, though not necessarily any folding.)Causes of folding Folds appear on all scales, in all rock types, at all levels in the crust and arise from a variety of causes. Layer-parallel shorteningWhen a sequence of layered rocks is shortened parallel to its layering, this deformation may be accommodated in a number of ways, homogeneous shortening, reverse faulting or folding.  The response depends on the thickness of the mechanical layering and the contrast in properties between the layers.  Ifthe layering does begin to fold, the fold style is also dependent on these properties. Isolatedthick competent layers in a less competent matrix control the folding and typically generate classic rounded buckle folds accommodated by deformation in the matrix.  In the case of regular alternations of layers ofcontrasting properties, such as sandstone- shale sequences, kink-bands, box-folds and chevron folds arenormally produced.Fault- related foldingMany folds are directly related to faults, associate with their propagation, displacement and the accommodation of strains between neighbouring faults. Fault bend foldingFault bend folds are caused by displacement along a non-planar fault. In non-vertical faults, the hangingwalldeforms to accommodate the mismatch across the fault as displacement progresses.  Fault bend foldsoccur in both extensional and thrust faulting. In extension, listric faults form rollover anticlines in theirhanging walls. In thrusting, ramp anticlines are formed whenever a thrust fault cuts up section from onedetachment level to another.  Displacement over this higher-angle ramp generates the folding. Fault propagation folding Fault propagation folds or tip-line folds are caused when displacement occurs on an existing fault without further propagation. In both reverse and normal faults this leads to folding of the overlying sequence, often in the form of a monoclineDetachment folding When a thrust fault continues to displace above a planar

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

detachment without further faultpropagation, detachment folds may form, typically of box-fold style.  These generally occur above a good detachment such as in the Jura Mountains, where the detachment occurs on middle Triassicevaporites. Folding in shear zonesShear zones that approximate to simple shear typically contain minor asymmetric folds, with the direction of overturning consistent with the overall shear sense. Some of these folds have highly curved hinge lines and are referred to as sheath folds.  Folds in shear zones can be inherited, formed due to the orientation of preshearing layering or formed due to instability within the shear flow Folding in sediments Recently deposited sediments are normally mechanically weak and prone to remobilisation before they become lithified, leading to folding. To distinguish them from folds of tectonic origin, such structures are called synsedimentary (formed during sedimentation). Slump folding:  When slumps form in poorly consolidated sediments, they commonly undergo folding,particularly at their leading edges, during their emplacement. The asymmetry of the slump folds can beused to determine paleoslope directions in sequences of sedimentary rocks.Dewatering:  Rapid dewatering of sandy sediments, possibly triggered by seismic activity, can causeconvolute bedding.Compaction: Folds can be generated in a younger sequence by differential compaction over olderstructures such as fault blocks and reefs.  Igneous intrusionThe emplacement of igneous intrusions tends to deform the surrounding country rock. In the case of highlevel intrusions, near the Earth's surface, this deformation is concentrated above the intrusion and often takes the form of folding, as with the upper surface of a laccolith.Flow foldingThe compliance of rock layers is referred to as competence: a competent layer or bed of rock can withstand an applied load without collapsing and is relatively strong, while an incompetent layer is relatively weak.  When rock behaves as a fluid, as in the case of very weak rock such as rock salt, or any rock that is burieddeeply enough, it typically shows flow folding (also called passive folding, because little resistance isoffered):  the strata appear shifted undistorted, assuming any shape impressed upon them by surroundingmore rigid rocks. The strata simply serve as markers of the folding.  Such folding is also a feature of manyigneous intrusions and glacier ice. Principle Of The Seismic Methods Of Subsurface Investigation: INTRODUCTION  Seismic refraction is a geophysical method used for investigating subsurface ground conditions by utilizing surface-sourced seismic waves.  Data acquired on site is computer processed and interpreted to produce models of the seismic velocity and layer thickness of the subsurface ground structure.  The method iscommonly used for measuring the thickness of overburden in areas where bedrock is at depth, and assessing ripability parameters. OPERATION  Pulses of low frequency seismic energy are emitted by a seismic source such as a hammer-plate, weightdrop or buffalo gun.  The type of source is dependant on local ground conditions and requireddepthpenetration.

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 Explosives are best for deeper applications but are constrained by environmental regulations.The seismic waves propagate downward through the ground until they are reflected or refracted offsubsurface layers.  Refracted waves are detected by arrays of 24 or 48 geophones spaced at regularintervals of 1 - 10 metres, depending on the desired depth penetration of the survey.  Sources arepositioned at each end of the geophone array to produce forward and reverse wave arrivals along thearray.  Additional sources may be used at intermediate or off-line positions for full coverage at all geophonepositions.

DATA INTERPRETATION  Geophones output data as time traces which are compiled and processed by the seismograph. The basiccomponents of a seismic trace are the direct wave, the reflected wave and the critically refracted wave.  Wave refraction occurs at interfaces in the ground where the seismic velocity of the lower layer is greaterthan the velocity of the overlying layer.  This condition normally applies in near surface site investigationswhere soil or fill overlies bedrock.

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UNIT V GEOLOGICAL INVESTIGATION

Remote sensing for civil engineering applications; Geological conditions necessary for design and construction of Dams, Reservoirs, Tunnels, and Road cuttings. Coastal protection structures. Investigation of Landslides and earthquakes - causes and mitigation , seismic zonation – seismic zones of India. Introduction About Remote Sensing: Every object on earth emits its own internal energy according to its molecular andatomic structure, in addition to reflecting sun light during the day time. This radiationscan be registered by sensors in several wavelengths, including those in the infrared andmicrowave regions of the spectrum. When such sensors are installed on aircrafts or onsatellites they can record the earth’s objects from for off distances. Such distant (Remote)acquisition of information about the objects on the earth’s surface is known as remotesensing. Aerial Photography & Imageries: The photographs of the earth taken from aircrafts are called the aerial photographs,while the pictures taken from the satellites are called the imageries. Aerial Photographs: Aerial photographs of the region are taken by cameras placed in the aircrafts. Aerialphotos give three dimension of the photographed area. These photos contain a detailedrecord of the ground at the time exposure. Satellite Imageries: The satellite imageries can either be read manually like aerial photographs, or with the help of computers. Geographic Information System; The modern computers can process maps and data with suitable computerprogrammer. The process of integrating and analyzing various types of data with the helpof computer is known as geographic information system. Applications Of Remote Sensing: General geological mapping, mineral prospecting, petroleum exploration, groundwater exploration, engineering .uses of site rocks, disaster studies, coastal geologicalstudies. Geological Considerations Involved In The Construction Of Buildings Basic requirements of a building foundation, building foundation on soils, building foundation carried to the deep hard rocks, building founded on surface bed rocks, types of settlement in buildings. Air Photos: Shape and size, flight and photo data, scale. Kinds Of Air Photos: Vertical air photos, oblique air photos, anusaics, photostrips, stereoprain. Stereo Meter: The instrument is used under a mirror stereoscope for measuring heights and areas of objects from air photos.

SEDIMENTARY ROCKS:

 Mud cracks  Tensile shear joints

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METAMORPHIC ROCKS:

 Mural joints  Sheet joints  Shear joints  One set of joint are dominant then they are called primary joints, engineering .

SIGNIFICANCE OF JOINTS:

 Spacing of joints  Length of joints  Block size  Width of joints  Seepage of water through joints  Filled materials and its nature UNCONFORMITY: It is defined as a surface of erosion or non deposition occurring within a sequence of rocks. TYPE OF UNCONFIRMITY: Angular unconformity Disconformity Non- conformity Local unconformity Regional unconformity ANGULAR UNCONFORMITY: The different inclinations and structural features above and below the surface of unconformity The sequence below the unconformity may be steeply inclined folded and faulted. This represent to older formation. T he sequence above the surface of unconformity represent the younger formation DISCONFORMITY: In this type of unconformity in which the beds lying below and above the surface of erosion are nonn deposition such an unconformity become evident only after through investigation involing drilling through the strata NON-CONFORMITY: In bedded sedimentary rocks overly the non beded igneous mass this structure is called non conformity REMOTE SENSING TECHNIQUES Remote sensing is the science, art and technology of obtaining information about the object, throughthe analysis of data acquired by a device this is not in contact with the object under the investigation.Various objects are identified with the help of variation in the reflected electromagnetic radiation reflected by different earth’s objects. A remote sensing system, therefore, must be sensitive enough tocapture the changes in the reflected electromagnetic energy. An ideal remote sensing may have thefollowing components.Source of electromagnetic energyMedium which interacts with this energyGround objectsSensor to detect and record the changes in electro-magnetic energyElectromagnetic radiation: Sun is the source of light. It radiates the heat and light energy in the form ofelectromagnetic radiation, the EMR comprises various rays such as , X- rays UV, Visible,Infrared, thermal inferred, microwave and radio wave. , X- rays and UV are observed andreflected by upper layer of atmosphere, which is most useful for remote sensing hence it is known asatmosphere window.

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The part of the electromagnetic radiation from visible to microwave is called electromagnetic spectrum(EMS).  Various components of an electromagnetic spectrum with their wavelength and frequency areshown in the above figure.  Principle:  All objective on the earth reflective absorb or radiate energy in the form of electromagneticwaves coming directly from the sun.  The electromagnetic radiation (EMR) reflected from the objective istransmitted through the atmosphere. The remotely placed sensors can pickup the transmitted energy,record and form an image.  This image data is sent to the earth recording stations, where all the data isrecorded on high density digital tapes.  Information about an object depends upon its spectralcharacteristic, which itself depends upon the nature of the object and its environment.  The electromagnetic radiation travelling through the atmosphere gets modified by absorption and or scattering

.

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Remote sensing plate form:

 Plate form is defined as a stage of sensor or camera. They play vital role inremote sensing data acquistation.  They are necessary to correctly position the sensors that collect datafrom the objects of interest.  The platforms may be air-borne, or space-borne, depending upon theobjects under study on earth surface and also on the sensor employed. Ballons, Aircraft, and Satellitesare the common remote sensing platform.

Balloons: These are designed and used for specific projects. Through the use of balloon is commonlyrestricted by meteorological factors, there application in resource mapping has been significant useful.Balloons are usually of two types, a) Free balloons and b) Threaded balloons. Aircraft: aircraft are commonly used as remote sensing plate forms for obtaining aerial photographs.

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They considered useful for regional converge and large scale mapping. Space born plate form:  Satellite has provided to be vital use in natural resource mapping,  meteorological and communication application applications.  Satellites are free- flying orbiting vehicles,whose motion is governed by the gravity, and atmosphere based on well-known kepler’s law’s.  Broadly,satellites can be grouped under two categories depending upon the types of orbits in which they move. Geostationary satellite Altitude - 35,000km Orbital Movement - Parallel to Earth Rotation Uses - Communication Example - GOBS, GMS, INSAT etc Sun-Synchronous or Polar orbiting satellite Altitude - 800-900km Orbital Movement - Pole to Pole Uses - Earth Observation Example - LANDSAT, SPOT, IRS, IKNAS, QUAKE BIRD etc

Sensor system:  In remote sensing, the acquisition of data is dependent upon the sensor system used.Various remote sensing platforms are equipped with different sensor systems.  It is a device thatreceives electromagnetic radiation, converts it into a signal and presents it in a form suitable forobtaining information about the land or earth resource as used by an information gathering system.Sensor can be grouped, either on the basis of energy source or on the basis of wave bonds employed.Based on the energy source, sensor are classifies as follows. Sensor Classification Based on the energy source Sensor May be classifies in to the followings:  Active Sensors (Sensor which produce the EMR by its own i.e RADAR)  Passive Sensors (Sensor depends the suns EMR i.e., MSS, TM, XS, LISS, PAN, WiPS etc)

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 Passive Sensor further divided into number of following types based on function of sensor in EMR>  Photographic Camera (Operated in single band from 0.4-0.7mm)  Return Beam Vidcon (Operated in Green, Red, NIR)- RBV in Landsat and TV in Bhaskara  Thermal Sensor (Operated in Thermal Infrared Region)  Optical and Mechanical Sensors (Operated in 0.5-1.1 mm) MSS and XS Radar and MicrowaveSensor (Operated in Microwave Region) SLAR, SAR  Advanced Remote Sensor (Operated in GBR and IR) LISS-II, LISS-III, LISS-IV, WiPS, PAN, TMParameter of sensor: Spatial Resolution : The minimum detectable area on the ground by a detector placed on a sensor Spectral Resolution : The small amount of spectral changes be detected by the sensor. Radiometric Resolution : The presence of grey level Temporal Resolution : Smaller period of repetitive coverage Remote Sensing Satellite: Remote sensing, as conceived today for natural resource mapping was started with the launching of the first earth resource. Technology’s satellite (ERTS) now known as LANDSAT-1, by USA in 1972 since then, with the advancement in sensor technology, a number ofremote sensing earth resource satellite have been launched. The important milestones crossed so farin achieving end-to-end capability are LANDSAT Series, 1, 2, 3, 4, 5, 6 and 7; Frances satellite 1, 2,and 3, Indian polar satellite Bhashkara 1&2, IRS 1A/ IRS 1B/IRS 1C/IRS 1D/IRS P2/IRS P3/IRS P4/IRSP5/IRS P6& Indian meteorological satellite INSAT 1A/1B/1C/1D and 2A/2B/2C/2D/2E etc., Factors Of Landslides. LANDSLIDES A temporary instability of superficial mass of soil and rocks, consolidated or unconsolidated, may leavetheir original position abruptly or extremely slowly and start either a downward movement or verticallydownward sinking thus giving rise to baffling situation. These movements may entitle to loss toproperty and life. Such movements of the ground have been termed as Landslides or Land slip or MassMovement Type of Landslides The landslides can be classified into three namely 1) Flowage 2) Sliding and 3) Subsidence based onthe rate of movement, nature of the mass involved in failure and degree of saturation where applicable Flowage: It is defined as downgrade movement of mass along no defined surface of failure. Massinvolved in this type of failure is primarily unconsolidated or loosely packed or disintegrated and decaymaterials and these materials behave as if it has its own shear failure surface. The result is that themovement is highly irregular (Fig). Flowage is further distinguished into slow and rapid flowage. In thefirst group, is not easily perceptible. The rapid flowage, however the movement of failing mass may beeasily visible and it moves few meters a day

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Translational slides: The surface of failure is generally planner in character, speed of failure is quiterapid and the nature of mass involved in failing may be rock block, rock slab, debris and soil cover or even a mixture of all of them.

Radial Slides: In such slides, the failing surface is generally curved in character and the speed of failure is also quite rapid. The materials involved in failure tilt at the rear end and heaves up at the front or toe.

Rock Toppling and falls: Surface layer of rock and soils on the steep slopes that are likely to fail in the form of falls. Subsidence: It is defined as sinking or setting of the ground in almost variously downward directionwhich may occur because of removal of natural support from the underground or due to compaction ofthe weaker rocks under the load from overlying mass. As a result the natural ground fill suffers a sinking, downward movement. Causes of Landslides: Many factors are known to cooperate in causing a mass of materials to flow or fail or fall, some of themplay a direct role and are easily understood whereas other are indirectly responsible for the instabilityof the land mass, Bases on this the land landslides operated by internal forces and external forcesInternal Forces: It includes nature of the slope and the water content are very crucial in defining thestability of ground anywhere. The composition of the ground materials and

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT the geological character ofthe area are other two internal factors that determine to a great extent if a land mass in a given areawould be stable or not. The role these natural factors play in the stability of the land mass are as follow. The Nature of Slope: Some slopes are very stable even when very steep, whereas others are inherently unstable, and may fail repeatedly even at very gently angles. Since a great majority of massfailures are confined to slope only, it is reasonable to conclude the nature of a slope may be a decidingfactor in defining the stability or otherwise of a land mass.

The Role of Water: Both surface and subsurface water causing mass movement. Water that penetratesthe soil and rocks thought seepage and moves into the pores of the mass may be the causes of uplift orpore-pressure within the mass under consideration. Water that accumulates at the back of a mass mayexert a pressure, parallel to the direction of flow and add to the shearing forces causing instability. Composition of the Mass:  Some materials are stable in a given set of conditions of slope and watercontent whereas other may be unstable.  Crystalline igneous rocks like granites and gabbros,metamorphic rock like marbles, quartzite and gneisses may be stable even with vertical slopes whereasthe same cannot be said about chalk- a soft variety of limestone, or shale or clay stone or soil.  It is,therefore, obvious that a fundamental character that is responsible for the stability of mass is itscomposition, which has both physical and chemical implication. Geological Structure: Geological structures are of great significance in defining the stability of mass,especially in rocks. These structures may be divided into three classes,  The bedding plane in structure,  The Schistosity and  The jointing Structure i). Bedding plane in structure:  Many sedimentary rocks are layered or stratified and thickness of layersmay range from a few centimeters to many meters.  The dip of the stratified rocks exerts very importantinfluence on the stability of slopes. If the layer is horizontal, such rock slopes of the natural valleys andartificial cuts are stable at all the angle up to 90°.  When they fall it may be due to presence ofsecondary joints or related features.

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If the layers are inclined, in such a situation, assuming that the rock is free from any other type of discontinuities, the stability of a slope will depend primarily on the condition whether the layer aredipping backwards into the mountain or forward into the valley. ii). Schistosity: Schisotsity, foliation and cleavage structures are behaving as surface of weakness andare prone to failure. This is primarily due to the fact that weathering in these rocks takes placealongthese planes. iii). The Jointing structures: Joints of any type are always to be studied with great caution in rocksmaking slope for two reasons: Firstly, very few rocks are free from these structures which may occur due to tension, compression orshear to which these rocks have been subjected since their formation.Secondly, they occur in sets or groups effecting the rock from the surface to considerable depth andeventually reducing the shear strength of the rock mass considerably. External Forces: The external features are also influence the cause of landslides. Vibration:  A mass perched on slope may be stable but critically; the gravitative forces have not yetovercome its frictional resistance.  A slight vibration or jerk to the mass may be sufficient to disturb thisequilibrium and the mass becomes unstable.  Such vibrations are easily available from heavy blastingand heavy traffic on hill roads.  Another important external factor is the removal of the support at the foot of the slope, as duringexcavation for road widening, without due regard to the critical condition of stability.  The slope thatmight have been previously stable becomes hazardous after such an excavation. Geological Processes That Result In Coastal Erosion COASTAL PROTECTION  Coast is defined as a boundary between sea and mainland. It has been shaped by varying influence oftectonic activity and instability of sea level.  Coast is associated with the sea and may include areas ofcliffs, dune, beaches and even hills and plains and it has been affected by marine processes such astides, winds, waves and current. In general coasts that are composed of soft, unconsolidated materials,such as sand which changes more rapidly than coasts composed of rock. Types of Coast According to Johnson, the coast may be classified in to two types that is a) Submerged coast and b)Emerged coast.

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 It is based on sea level related with climate and tectonic activity.  The submerged coastis the coastal interior; the land immediately behind the shore zone (whose inner limit is defined by thehighest storm and tide waves) has an intermediate inner limit. The erosional features like Cliffs, Sheetsand Gullies are seen along the erosional coast.  While in the case of an emerged coast, the coastal tractwhere the seaward migration of the coastal tract is a low land, depositional features like deltaicsedimentation, estuarine, marsh and sand dunes are the characteristic features. Importance of Coast  The coastal environment is very dynamic with many cyclic and random processes owing to a variety ofresources and habitats.  Further the coastal ecosystems are the most productive ecosystems on earth.About 60 percent of world population lives near the coast and in one way or other depends directly orindirectly on the coastal zone and its resources (Like Coral reefs, Mangrove, Seaweeds, Sea grass,Salt marsh, Beach etc).  Thus the coastal zone plays a vital role on the nation’s economy. Coastal Problems in India  The coastal area in India faces a wide range of problems. A recent regional survey conducted by  International Ocean Institute, Operational Center at Chennai revealed several problems.  As per thesurvey, in India, population pressure has been considered as the most important problem. For example, in the state of Tamilnadu, the population density in coastal area is 528 per sq.km against 372 per sq.km which is state average.  In parts of coastal metros like Bombay, Calcuttaand Madras, the population pressure led to resource depletion and environmental degradation.The major activities that are responsible for coastal population in India are discharge and disposal ofdomestic and industrial wastes, discharging of coolant waters, harbor activities such as dredging, cargohandling, dumping of ship wastes, spilling of cargo’s such as chemical and metal ores, oil transport andfishing activity, etc.  Domestic waters are discharged mostly in untreated conditions due to lake oftreatment facilities in most of t he cities or towns.  India is one of the largest industrialized nations in theVisakhapatnamand Calcutta are situated on or near the coastline.  The estimated total quantity of waste discharged bythese industries is estimated to be approximately 700 million cu.m  The coastal erosion is caused by wave braking, reduction in sediment input to coast, tectonic  upheavals and rise in sea level. These causes are not only natural, but also, due to human influence.  Inwest coast, erosion is very severe along Kerala coast. In Karnataka, about 73 km of the coast isaffected by erosion.  Along the east coast the coastal erosion is moderate. In Tamilnadu, about 80 km ofthe coastline is affected.

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 In Orissa, about 30 to 40 km are affected. In West Bengal, erosion occurs in180 km, along the coastline stretching from the confluence of the river Hooghly in the west to theconfluence of the river Jadgan in the east.  The rate of erosion is as high as 30 m/year.  In India, nearly 150 million people are prone to natural hazard in coastal areas. Bay of Bengal is one ofthe five cyclone prone areas of the world.  The coastal regions surrounding this bay are frequentlyaffected by flooding from the sea as well as the rivers due to tropical cyclones and related storm surgesand heavy rainfall.  Between the year 1990 and 1995 in the state of Andhra Pradesh, more than 1100human lives were lost and properly worth of Rs.23, 000 million were damaged.  In Tamilnadu during theyear 1990 and 1995, the damages caused to property were worth of Rs. 5, 800 million and the loss ofhuman lives was more than 500. Shoreline Erosion and Accretion Shoreline is one of the most rapidly changing landforms of the earth. The geomorphic processes oferosion and accretion, periodic storms, flooding and sea level changes continuously modify the shoreline. The rate of shoreline-change varies depending upon the intensity of the causative forces,warming up of oceanic water and melting of continental ice sheets etc, which result in submergence oremergence of land.The coastal erosion and accretion processes are not newphenomena. Generally the main causes ofthese processes can be thought of (i) beach configuration (ii) tectonic movements in the coastal beltand the near shore (iii) presence of mud blanks (iv) gradual climate changes (v) reduction in thedischarging of sediments from rivers and (vi) manmade activities along the coast. Tamil Nadu with a coastal length of 980 km is the second largest coast in India. This state experiencetwo monsoon periods, one is active from mid-June to mid-September (i.e, southwest monsoon) and theother is active from mid-October to mid-January (i.e., northeast monsoon). All the districts of the studyarea are affected by cyclonic storms almost every alternative year (For example, during the period1877-1977, the coast has been hit by the storms for at least 50 times). During certain years, the coasthas been hit by cyclonic storms even more then once. Management measures of Coastal protection The following measures are some management measures for coastal protection:  To create awareness among the coastal communities in the study area, in order to protect and  conserve the coastal area through effective involvement of educational institutions and NGOS  Stringent measures need to be under taken with immediate effect to ban coastal and coral  mining and to take into task those involved in or those who encourage the exploitation of corals  for any purpose. Patrolling the coast to check coral and coastal mining should be carried out.  Law should be enacted to regulate and stop trawl boat operation in the zone earmarked for

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

 non-mechanized boat. The Department of Forest and the Department of Fisheries should take  steps to stop anchoring of vessels on coral reefs, pair trawling and dynamite fishing.  Indiscriminate picking of budding seaweeds need to be banned.  Commercial shell collection should be controlled and closely monitored.  Marine Resource Management Centers should be established to improve the skills of  fishermen communities in areas other than coastal mining, which in turn will lead to efficient management of coast.  Deforestation along the coast and islands should be banned. The forest Department should  take up a forestation along the coast and islands to protect soil erosion.  Discharging of untreated sewage and urban wastes into the coastal waters should be totally banned.  Construction of embankment walls along the coast to prevent the coastal erosion etc.  Coastal protection structures Necessity for protection Incessant natural phenomena such as winds, waves,currents and cyclones occurring continuously affect the shore line . due to these phenomena there may be erosion or accretion of shore materials.Change in the shore line caused due to excessive siltation at ports, demand removal of excess materialb dredging. On the other hand erosion may lead to scoring of neighbouring structures. Compared tostructures in the interior land , costal structures are subjected to more severe forces and need constantmaintenance. Hence the shore line has to be protected so as to maintain the requirement. Shore protection works Shore protection works are involved in  To protect an exposed beach line  To stabilize the existing beach  To restore eroded beach  To create and stabilize artificial beach Shore protection wors in general are:  Sea walls and bulheads  Protective beaches  Sand dunes  Groynes  Off shore breakwater Sea walls and bulheads  These are the structures constructed parallel to the shore line special to separate land area from waterarea. These are constructed to stop further recession of shore line.  Alignment of such wall should be straight as far as possible and may be curves. Abrupt change  in direction may cause added wave forces. Bulk head are meant to retain the earth behind from slidingand also provides a wave protection device.  Sea walls are used where the land to be protected in a developed one and waves effects aresevere. Sea walls are ver massive and expensive. These walls prevent

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

shoreward movements of highwater line. sheet pile walls or solid reinforcement mason walls ma be used.  Inclined shores are provided with stone rivertment.lie sea walls revetments are used mainl to  protect the land and upland propert against wave action and also function as a retaining wall.  Protective beaches  Beaches of suitttable dimensions are effective in dissipating energy and alsop provide  protection to the adjacent upland. Eroded beaches an be wade good b planning beach fill so as toensuresandsuppl at the required rate.  Periodic repleinishment of stockpile is called artificial beach nourishments. It also maes good  the deficiencies in natural sand suppl and protects the shore beond the beach at a low cost.  Sand dunesThe are formed along the coast which prevent the free movement of tides and wavws into the areabehind it. Sand dunes with time may migrate to the adjacent areas and damage the propert. Dune sandma stabilize by vegetation. Under severe weather conditions the formation will be different.GyronesIt is another shore protection tructures. This is used to built a protection beach to retard erosion.it alsoprotect the toe sea walls or bulkheads  Gyrones are constructed well into the sea perpendicular to shore line .Gyrones  Ma also be constructed with certain angle to shore line.  A series of Gyrones acting together to protect a shore line is called Gyronessstem. Spacing  between Gyrones is such that the length and spacing are in the ratio of 1:1 to 1:3. Closer spacing andspacing beond 1: 3 are inefficient.  Gyrones are expected to resist wave action and sand pressure. Gyrones can be constructed of  timber piles or steel sheet piles. Off-shore breakwaters Off-shore breakwaters serve in several wasy such as, 1. Protecting an area from wave action 2. Shore protection structure 3. Acts as a trap for littoral drift These are of mound type breakwaters which provide protection to harbor entrances. Some timesoffshore breakwaters are constructed off shore of sea walls so as to reduce the determined forces onthe sea walls. Littoral movements are very effectively intercepted by off shore break waters 4. Using case studies, explain how groundwater investigation and exploration is carries out by civilengineers. [AU NOV/DEC 2015] GROUNDWATER INVESTIGATIONS In addition to pumping tests, Groundwater Engineering provides a complete service for a wide range ofgroundwater investigation techniques. Desk top studies and research into existing information can be a very cost effective way to identifygroundwater problems at an early stage. Numerical groundwater modelling can be used

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT to assess likelyflow rates, distance of influence and the potential for adverse environmental impacts. INSTALLATION OF MONITORING WELLS Monitoring wells and specialist piezometers installed in advance of dewatering works can providevaluable information on hydrogeological conditions at a site. PUMPING TESTS Pumping tests are a reliable way of determining the mass permeability of soils and rocks, and of providing other information on groundwater conditions. BOREHOLE PERMEABILITY TESTS A range of tests can be carried out in individual boreholes, including rising and falling head tests, constant head tests, Lugeon tests, Lefranc tests and packer tests. When carried out in accordance withrelevant published standards and interpreted appropriately, such tests can provide some indication ofpermeability values and groundwater conditions. GROUNDWATER MONITORING SYSTEMS  Groundwater monitoring systems can play an important role in construction projects to allowgroundwater conditions to be monitored and to provide data for design purposes.  Groundwater potential evaluation for a given area/basin requires integrated approach.  Detailed quantification of theamount of groundwater demand a detailed water balance study and defining the boundary conditions, establishmentof the lateral and vertical extent of aquifers and confining beds. In the absence of detailed hydro meteorological andhydrogeological data, groundwater potential evaluation tends to be more semi- quantitativemainly based ongeophysical investigation.  The method followed in this study, for the most part, was depending on the short-term field hydrogeologicalinvestigation and surface geophysical surveying. Both approaches provide information on the availability ofgroundwater in a semi-quantitative sense.Geophysics provides no information on the exact amount of groundwater available in the subsurface.  The amount canonly be estimated when the geophysical survey is supported by the local hydrogeological features such as rechargepotential, availability of permeable rocks, catchments areas, etc.All the interpretations shown in the geophysical part of this study are made semi-quantitatively by integrating thehydrogeological field observations with the geophysical signature obtained from the VES data.  The recommendationsof the likely depth of drilling are made on the basis of the VES data and the nearby well data. The supervisor/ hydrogeologist can recommend the accurate drilling depth during the drilling operation.  For instance in some sites wheregeophysics does not give conclusive answers on the total depth of the aquifers, yield of the well can be defined byusing provisional tests with the compressor of the drilling machine. Causes Of Inherent Weakness In Rocks In the majority of cases the main trigger of landslides is heavy or prolonged rainfall. Generally this takesthe form of either an exceptional short lived event, such as the passage of a tropical cyclone or eventhe rainfall associated with a particularly intense thunderstorm or of a long duration rainfall event withlower intensity, such as the cumulative effect of monsoon rainfall in South Asia.  In the former case it isusually necessary to have very high rainfall intensities, whereas in the latter the intensity of rainfall maybe only moderate - it is the duration and existing

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pore water pressure conditions that are important. Theimportance of rainfall as a trigger for landslides cannot be underestimated. A global survey of landslideoccurrence in the 12 months to the end of September 2003 revealed that there were 210 damaginglandslide events worldwide. Of these, over 90% were triggered by heavy rainfall.  One rainfall event forexample in Sri Lanka in May 2003 triggered hundreds of landslides, killing 266 people and renderingover 300,000 people temporarily homeless.  In July 2003 an intense rain band associated with theannual Asian monsoon tracked across central Nepal, triggering 14 fatal landslides that killed 85 people.  The reinsurance company Swiss Re estimated that rainfall induced landslides associated with the1997-1998 El Nino event triggered landslides along the west coast of North, Central and South Americathat resulted in over $5 billion in losses.  Finally, landslides triggered by Hurricane Mitch in 1998 killedan estimated 18,000 people in Honduras, Nicaragua, Guatemala and El Salvador. So why does rainfalltrigger so many landslides? Principally this is because the rainfall drives an increase in pore waterpressures within the soil.  The Figure A illustrates the forces acting on an unstable block on a slope.Movement is driven by shear stress, which is generated by the mass of the block acting under gravitydown the slope. Resistance to movement is the result of the normal load.  When the slope fills withwater, the fluid pressure provides the block with buoyancy, reducing the resistance to movement. Inaddition, in some cases fluid pressures can act down the slope as a result of groundwater flow toprovide a hydraulic push to the landslide that further decreases the stability.  Whilst the example givenin Figures A and B is clearly an artificial situation, the mechanics are essentially as per a reallandslide. Dam Disaster Dams may be defined as a solid barrier constructed at a suitable geological location across a river valley. Objectives of Dam Construction The followings are the objectives of the dam construction:  Generating the hydroelectricity  Providing water for irrigation  Providing water supply for industries  Fighting drought and controlling of floods  Providing navigational facilities Classification of Dams Dams are classified 1) Gravity Dams, 2) Arch Dams and 3) Embankment Dams. This classification isbased on design, materials, and size of the construction. Gravity Dams: It is a solid masonry or concrete structure, generally of a triangular profile, which is sodesigned that it can withhold a particulate volume of water by virtue of its weight. All force arising insuch a dam as due to the thrust of the impound water and the massive weight of the dam materials areassumed to the foundation rocks. This kind of dams is always very important and costly structure,therefore its design and construction should always be done very carefully.

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Arc Dams: It is arc-Shaped solid structure mostly of concrete, which is designed in such a way that amajor part of the thrust forces acting on the dam are transmitted mainly by the arch action, on to theabutment rocks, that is rock forming the left and right sides of the stream valley. Hence such damescan be built even on those sites where the foundation rocks may not be sufficiently strong.

Embankment or Earth Dams: The embankment dams are generally trapezoidal in section constructedof selected soil or earth obtained from the borrow pits of the adjoining areas. Sometimes anembankment dams also contains a hard rock-fill, depending upon the height, base width and length ofthe dam as shown in the figure.

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Suitable Geological Site for Dam Construction To select suitable site for dam construction some preliminary geological survey of the entire catchmentsarea to be done followed by detailed geological mapping by remote sensing method. It can gives theinformation of 1) Topographic features, 2) Natural Drainage pattern, 3) General Character, 4) Structuralfeatures of rocks, such as fold, fault and joints and 5) trend and rate of weathering. Such a study wheninterpreted properly, would ruled out some sites for the dam placement and help in identifying the mostsuitable locations topographically and economically, where further detailed geological investigationcould be carried out. For obtaining the above information, remote sensing and conventional geologicalsurvey need to be conducted.Geology of the site Lithology: To understanding the lithology of the area is very important to select the site for dam construction. It can be possible through conventional and remote sensing methods. Such study revealsthe type, composition and texture of the rocks exposed along the valley floor, yet it is of greatsignificance to know what class of rocks makes up the area; igneous, sedimentary or metamorphic.Lithology interpretation is to identify information of rock unit with reference to their physicalcharacteristics, topography, etc. This is based primary on photo-interpretation elements, e.g, tone,pattern, size, texture, shape and relationship condition in photos and image and terrain parameters andassociated features with convergence of evidence. Examples: Intrusive rocks can be identified from satellite imagery using the following interpretation key: Colour/Tone - Light tone or medium red Texture - Coarse to fine Pattern - Sub dendrite Bedding - Non-bedding Boundary - Round cliffs Structure - Lineament, syncline and anticline. Structure: The interpretation of structural features is very important for sit selection for dam.

Thestructural features like folding, faulting, joints, shear zones and fault zone and associated features canbe identified through remote sensing method.

Example:  The fault is easy to pick up on aerial data and satellite image by sharp topographic break andlinear alignments of structure, water bodies or vegetation.  Dip and Strike, Fault, Folds and Joints aresome important features of rocks for dam foundation. Dip and Strike:  The bedded rocks are stronger in composition, and can bear greater stress when  applied normal to the bedding planes than the stress applied along the bedding planes. Thus the desired conditions are that the resultant thrust, should be perpendicular to the bedding plane.

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 The bedding generally upstream offer best resistance to the resultant thrust and also obstructs the leakageof water than those dipping down-stream as shown in figures. Folds: The folded rocks are always under a considerable strain, and the same is released wheneverany kind of excavation is done through them or they are distributed by some external forces or stress. It is therefore desirable that a highly folded rock should always be avoided. If the engineer is compelled to a dopt such a site, he should see that the foundations of his dam should rest on the upstream limbs ofthe fold, if the fold is anticlinal in nature as shone in figure. But the fold is synclinal in nature; thefoundations of the dame should rest on the downstream limbs of the fold as shown in figure.

Different possible positions of a gravity dam A. On horizontal bed rocks – suitable condition B. On down stream dipping rocks – unsafe C. On upstream dipping condition – safe against R

Effect of folding on dam site Fault: It is always to avoid risk by rejecting a site on a fault, as the movement along the existing faultplane is much easier than along the any other plans. Even a slight disturbance may damage thestructure constructed on Fault. If the engineer is completed by the circumstances to adopt such asituation, then he should see that the site has the fewest disadvantages or no serious defects. It isadvisable in such cases to place the foundation of a dame upstream of the fault and not downstream ofit as shown in figure.Joints: No sites are totally free from joining.

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 Hence, sites cannot be abandoned, even if profuselyjointed. However, the detailed mapping of the aspects and character of joints as developed in the rockof proposed site has to be taken up with the great caution.  The geometry of joints, their intensity, natureand continuity with depths all must be established, and their effect on the site rocks are to be evaluatedand remedial measurement to be taken in advance.  Occurrence of micro joints has to be source ofmany risks.Engineering propertiesLithological and structural studies are not sufficient for the selection of site for dam.  A through testingboth in laboratory and in situ of the site rock for their most important engineering properties has to becarried out such as compressive strengths, shear strength, modulus of elasticity, porosity andpermeability and resistant to disintegration on repeated weathering and drying. Effects Of The Action Of Sea Waves On The Coastal Zones

Introduction About Coast

 Coast is defined as a boundary between sea and mainland. It has been shaped by varying influence oftectonic activity and instability of sea level.  Coast is associated with the sea and may include areas ofcliffs, dune, beaches and even hills and plains and it has been affected by marine processes such astides, winds, waves and current.  In general coasts that are composed of soft, unconsolidated materials,such as sand which changes more rapidly than coasts composed of rock. Types of Coast:

 According to Johnson, the coast may be classified in to two types that is  Submerged coast and  b)Emerged coast.  It is based on sea level related with climate and tectonic activity.  The submerged coast is the coastal interior; the land immediately behind the shore zone (whose inner limit is defined by thehighest storm and tide waves) has an intermediate inner limit. The erosional features like Cliffs, Sheetsand Gullies are seen along the erosional coast.  While in the case of an emerged coast, the coastal tractwhere the seaward migration of the coastal tract is a low land, depositional features like deltaicsedimentation, estuarine, marsh and sand dunes are the characteristic features. Importance of Coast  The coastal environment is very dynamic with many cyclic and random processes owing to a variety ofresources and habitats.  Further the coastal ecosystems are the most productive ecosystems on earth.About 60 percent of world population lives near the coast and in one way or other depends directly orindirectly on the coastal zone and its resources (Like Coral reefs, Mangrove, Seaweeds, Sea grass,Salt marsh, Beach etc). Thus the coastal zone plays a vital role on the nation’s economy. Coastal Problems in India

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

 The coastal area in India faces a wide range of problems.  A recent regional survey conducted byInternational Ocean Institute, Operational Center at Chennai revealed several problems. As per thesurvey, in India, population pressure has been considered as the most important problem.  Environmental degradation such as destruction of mangroves along with pollution and urbanization isconsidered as the next serious problem.  Traditionally, coastal areas are highly populated and developed. In India, out of the 3- mega cities withpopulation more than 10 million, Delhi (13.2 M), Bombay (16 M) and Calcutta (16.5 M) two are coastalcities i.e., Bombay and Calcutta. The population density is also more coastal areas than the nationalaverage.  For example, in the state of Tamilnadu, the population density in coastal area is 528 persq.km against 372 per sq.km which is state average. In parts of coastal metros like Bombay, Calcuttaand Madras, the population pressure led to resource depletion and environmental degradation.  The major activities that are responsible for coastal population in India are discharge and disposal of domestic and industrial wastes, discharging of coolant waters, harbor activities such as dredging, cargohandling, dumping of ship wastes, spilling of cargo’s such as chemical and metal ores, oil transport andfishing activity, etc.  Domestic waters are discharged mostly in untreated conditions due to lake oftreatment facilities in most of t he cities or towns. India is one of the largest industrialized nations in theworld. Major industrial cities and town such as Surat, Bombay, Cochin, Chennai and Visakhapatnamand Calcutta are situated on or near the coastline.  The estimated total quantity of waste discharged bythese industries is estimated to be approximately 700 million cu.mThe coastal erosion is caused by wave braking, reduction in sediment input to coast, tectonicupheavals and rise in sea level.  These causes are not only natural, but also, due to human influence. Inwest coast, erosion is very severe along Kerala coast. In Karnataka, about 73 km of the coast isaffected by erosion.  Along the east coast the coastal erosion is moderate.  In Tamilnadu, about 80 km ofthe coastline is affected. In Orissa, about 30 to 40 km are affected.  In West Bengal, erosion occurs in180 km, along the coastline stretching from the confluence of the river Hooghly in the west to theconfluence of the river Jadgan in the east.  The rate of erosion is as high as 30 m/year.  In India, nearly 150 million people are prone to natural hazard in coastal areas. Bay of Bengal is one ofthe five cyclone prone areas of the world.  The coastal regions surrounding this bay are frequentlyaffected by flooding from the sea as well as the rivers due to tropical cyclones and related storm surgesand heavy rainfall.  Between the year 1990 and 1995 in the state of Andhra Pradesh, more than 1100human lives were lost and properly worth of Rs.23, 000 million were damaged.  In Tamilnadu during theyear 1990 and 1995, the damages caused to property were worth of Rs. 5, 800 million and the loss ofhuman lives was more than 500.Shoreline Erosion and Accretion

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

 Shoreline is one of the most rapidly changing landforms of the earth. The geomorphic processes oferosion and accretion, periodic storms, flooding and sea level changes continuously modify the shoreline.  The rate of shoreline-change varies depending upon the intensity of the causative forces, warming up of oceanic water and melting of continental ice sheets etc,  which result in submergence oremergence of land.The coastal erosion and accretion processes are not new phenomena.  Generally the main causes ofthese processes can be thought of  Beach Configuration;  Tectonic Movements In The Coastal Beltand The Near Shore  Presence Of Mud Blanks,  Gradual Climate Changes,  Reduction In Thedischarging Of Sediments From Rivers And  Manmade activities along the coast. Tamil Nadu with a coastal length of 980 km is the second largest coast in India. This state experiencetwo monsoon periods, one is active from mid-June to mid-September (i.e, southwest monsoon) and theother is active from mid-October to mid-January (i.e., northeast monsoon). All the districts of the studyarea are affected by cyclonic storms almost every alternative year (For example, during the period1877-1977, the coast has been hit by the storms for at least 50 times). During certain years, the coasthas been hit by cyclonic storms even more then once. Management measures of Coastal protection The following measures are some management measures for coastal protection:  To create awareness among the coastal communities in the study area, in order to protect and  conserve the coastal area through effective involvement of educational institutions and NGOS  Stringent measures need to be under taken with immediate effect to ban coastal and coral  mining and to take into task those involved in or those who encourage the exploitation of corals  for any purpose. Patrolling the coast to check coral and coastal mining should be carried out.  Law should be enacted to regulate and stop trawl boat operation in the zone earmarked for  non-mechanized boat. The Department of Forest and the Department of Fisheries should take  steps to stop anchoring of vessels on coral reefs, pair trawling and dynamite fishing.  Indiscriminate picking of budding seaweeds need to be banned.  Commercial shell collection should be controlled and closely monitored.  Marine Resource Management Centers should be established to improve the skills of  fishermen communities in areas other than coastal mining, which in turn will lead to efficient management of coast.  Deforestation along the coast and islands should be banned. The forest Department should  take up a forestation along the coast and islands to protect soil erosion.

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 Discharging of untreated sewage and urban wastes into the coastal waters should be totally  banned.  Construction of embankment walls along the coast to prevent the coastal erosion etc.  Coastal protection structures  Necessity for protectionIncessant natural phenomena such as winds, waves,currents and cyclones occurring continuously  affect the shore line . due to these phenomena there may be erosion or accretion of shore materials.Change in the shore line caused due to excessive siltation at ports, demand removal of excess materialb dredging. On the other hand erosion may lead to scoring of neighbouring structures. Compared tostructures in the interior land , costal structures are subjected to more severe forces and need constantmaintenance. Hence the shore line has to be protected so as to maintain the requirement. Shore protection works Shore protection works are involved in  To protect an exposed beach line  To stabilize the existing beach  To restore eroded beach  To create and stabilize artificial beach  Shore protection wors in general are:  Sea walls and bulheads  Protective beaches  Sand dunes  Groynes  Off shore breakwater  Sea walls and bulheads These are the structures constructed parallel to the shore line special to separate land area from waterarea.  These are constructed to stop further recession of shore line.  Alignment of such wall should be straight as far as possible and may be curves. Abrupt change  in direction may cause added wave forces. Bulk head are meant to retain the earth behind from slidingand also provides a wave protection device.  Sea walls are used where the land to be protected in a developed one and waves effects aresevere. Sea walls are ver massive and expensive. These walls prevent shoreward movements of high water line.  sheet pile walls or solid reinforcement mason walls ma be used.  Inclined shores are provided with stone rivertment.lie sea walls revetments are used mainl to  protect the land and upland propert against wave action and also function as a retaining wall.  Protective beaches  Beaches of suitttable dimensions are effective in dissipating energy and alsop provide  protection to the adjacent upland.  Eroded beaches an be wade good b planning beach fill so as

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 toensuresandsuppl at the required rate.Periodic repleinishment of stockpile is called artificial beach nourishments. It also maes good the deficiencies in natural sand suppl and protects the shore beond the beach at a low cost. Sand dunes  The are formed along the coast which prevent the free movement of tides and wavws into the areabehind it. Sand dunes with time may migrate to the adjacent areas and damage the propert.  Dune sandma stabilize by vegetation. Under severe weather conditions the formation will be different.GyronesIt is another shore protection tructures.  This is used to built a protection beach to retard erosion.it alsoprotect the toe sea walls or bulkheads Gyrones are constructed well into the sea perpendicular to shore line .Gyrones  Ma also be constructed with certain angle to shore line.  A series of Gyrones acting together to protect a shore line is called Gyronessstem. Spacingbetween Gyrones is such that the length and spacing are in the ratio of 1:1 to 1:3. Closer spacing andspacing beond 1: 3 are inefficient.  Gyrones are expected to resist wave action and sand pressure.  Gyrones can be constructed of timber piles or steel sheet piles.  Off-shore breakwaters  Off-shore breakwaters serve in several wasy such as,  Protecting an area from wave action  Shore protection structure  Acts as a trap for littoral drift These are of mound type breakwaters which provide protection to harbor entrances. Some times offshore breakwaters are constructed off shore of sea walls so as to reduce the determined forces onthe sea walls. Littoral movements are very effectively intercepted by off shore break waters List The Causes Of Landslides.  The term landslide refers to the downward sliding of huge quantities of land masses of earth.  sliding occurs along steep slopes of hills or mountains.. It may be sudden or slow in its  occurrence.Also, in magnitude, it may be major or minor.Often, loose and un consolidatedsurface material undergoes sliding. But sometimes, hugeblocks ofconsolidated rocks may also be involved.  If landslides occur in places of importancesuch as highways, railway lines, valleys,reservoirs, inhabited areas and agricultural lands leadsto blocking of traffic, collapse of buildings, harm to fertile lands and heavy loss to life andproperty. In India,landslides often occur in Kashmir, Himachal Pradesh and in the mountains of Uttar Pradesh. CLASSIFICATION OF EARTH MOVEMENTS: All movements of land masses are referred to as landslides and grouped them under “earth movements”. The classification of earth movements us as follows:  Earth Movements  Earth Flows  Solifluction  Creep  Rapid Flows  Landslides

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

 Debris slides and slump  Rock slides  Rock falls SUBSIDENCE  Compaction  Collapse Earth Flows:  There are three types of earth flows viz., solifluction; creep and rapid flows. Solifluction refers to the downward movement of wet soil along the slopes under the influence of gravity.Creep refers to the extremely slow downward movement of dry surface material.  This is very imp from the civil engg point of view due to slow movement of mass.  On careful examination,bending of strata ; dislodgement of fence posts ; telephone poles, curvature of tree trunks; broken retaining walls etc offer clues to recognize creep. Rapid flows are similar to creep but differ with reference to the speed.  Rapid flows generally accompany heavy rains. Mud flows are similar to rapid flows. Landslides include Debris slides, rock slides and rock falls.  Debris slides are common along the steep sides of rivers, lakes. Debris slides of small magnitude are called slumps.  Rock slides are the movements of consolidated material which mainly consists of recentlydetached bedrocks. For eg: a rock slide that took place at Frank, Alberta in 1903 killing 70people. Rock falls refer to the blocks of rocks of varying sizes suddenly crashing downwards alongsteep slopes.  These are common in the higher mountain regions during the rainy seasons. Subsidence may take place to the compaction of underlying material or due to collapse. Subsidence due to compaction:  Sediments often become compact because of load.  Excessive pumping out of water and the withdrawal of oil from the ground also cause subsidence.  Subsidence due to collapse:  In regions where extensive underground mining has removed a large volume of material, the weight of the overlying rock may cause collapse and subsidence.

CAUSES OF LANDSLIDES: Landslides occur due to internal causes (inherent). The internal causes are again of various types such as Effect of slope; Effect of water; Effect of Lithology; Effect of associated structures ; Effect of human factors etc.. 1.Effect of slope: This is a very important factor which provides favourable conditions forlandslide occurrence.Steeper slopes are prone to land slips of loose overburdens due to gravity influence.However, it should be remembered that hard consolidated and fresh rocks remain stable evenagainst any slope. 2.Effect of water: The presence of water greatly reduces the intergranular cohesion of theparticles of loose ground causing weakness of masses and prone to landslide occurrence.Water, being the most powerful solvent, not only causes decomposition of minerals but alsoleaches out the soluble matter of rocks. This reduces the compaction of rock body and makes

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT it a weak mass. 3.Effect of Lithology; Rocks which are highly fractured, porous and permeable are prone tolandslide occurrence because they give scope for the water to play an effective role. In addition,rocks which contain clay minerals, mica calcite, glauconite, gypsum etc are more prone tolandslide occurrence because, all these minerals are easily leached out. 4.Effect if associated structures ; The geological structures such as bedding planes, joints, faults or shear zones are planes of weakness and cause landslide occurrence. 5.Effect of human factors  Human beings sometimes, interfere with nature by virtue of their  activities and cause landslides. For eg: laying roads ; railway tracks etc..  When construction works are carried out on hill tops, the heavy loads on the loose zone ofoverburden create a sliding of rock masses.Land slides in India: Land slides are reported in the hilly terrains in different regions of India.The most disastrous land slides that have taken place in recent past are in the Himalayanterrain in the North and the Nilgiri hill region in south.  In July 1970, heavy debris from Patalganga valley has been transported into Alaknanda in theGarhwal region of Uttaranchal. The flooding in Alaknanda due to these landslides has resulted ina silt and rock fragment accumulation of about 9 M cum.  Another disastrous land slide took place on 18th Aug 1998 in Malpa village which is located on  the banks of Kali River in Pithorgarh district of Kumaon Himalayas. The piled debris was  around 20 m in height.  In 1968, numerous landslides occurred during heavy rainfall of about 500 to 1000 mm in theDarjeeling and Sikkim regions where the 60 km highway between Darjeeling (West Bengal) andGangtok (Sikkim) was disrupted. EFFECTS OF LANDSLIDES:  From the civil engineering point of view, landslides may cause  disruption of transport  damaging roads and railways and telegraph poles  obstruction to the river flow in valleys  damaging sewage and other pipe lines.  destruction of buildings and civil structures Recent landslides in the Himalaya terrain are listed below: Himachal Pradesh region: Nathpa (Nov 1989): Road destroyed about a km Kullu (Sep 1995): Road 1km destroyed and 32 persons killed Uttaranchal region: Kalisaur ( July 1968): Road damaged extensively Malpa (Aug 1998): Road to Manasarovar damaged & 205 persons killed Jammu & Kashmir region: Nashri ( Jan 1982) Every year causes damage to the roads Malori ( Jun 1995): National Highway 1-A damaged and 6 persons killed West Bengal Region: Kalimpong, Darjeeling (Aug 1993):40 persons killed with heavy loss of property

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

Arunachal Pradesh Region: Itanagar ( July 1993): 2 km road damaged and 25 persons killed Mizoram region: Aizwal ( May 1995): 25 persons killed and road extensively damaged Nagaland region: Kohima ( Aug 1993): 200 houses and 5 km road damaged. 500 persons killed. Selected landslides in South India are listed below: Major Land slides took place in the Nilgiri Hill region include Runnymede, Glenmore, Coonoor areas. Amboori landslide in Kerala: On Nov 9th, 2001, a disastrous land slide occurred around Amboori (20 km from Thiruvananthapuram ) due to heavy rains and water logging. PREVENTION OF LANDSLIDES:  Provision of adequate surface and subsurface to enable water to freely drain out .  Construction of suitable ditches and waterways along slopes to drain off the water from the loose overburden.  Construction of retaining walls against slopes, so that the rock masses which rolls down is not only prevented from further fall but also reduces the slope.  Modifying the slopes to stable angles.  Growing vegetation to hold the material together.  Avoiding heavy traffic and blasting operations near the vulnerable places naturally helps in preventing the occurrence of landslides. Case Studies Of Structural Failures, Discuss The Importance Of Geological Investigations For The Design And Construction Of Large Civil Structures.  Ground-related factors have often been the origin of contractual claims with significant time and costoverruns on both large and small construction projects. According to European statistics, between 80%and 85% of all building failures and damages are related to unforeseen and unfavourable groundconditions.  Without adequate site investigation, clients are always exposed to the risk of costly delays,redesign and late project delivery arising out of unforeseen ground conditions; You pay for a groundinvestigation whether you have one or not . In 1994, the Latham Report stated that risk ...can bemanaged, minimised, shared, transferred or accepted;  it cannot be ignored . Unfortunately, when it comes to the risk of unforeseen ground conditions, ignorance on behalf of both the contractor andemployer often seems commonplace. As unforeseen ground conditions represent a huge area of risk, aconstruction contract either has to allocate the risk to a single party or distribute it between the parties.  The traditional method of controlling such risks has been through the use of thorough site investigationand competent geotechnical design, aiming to produce a robust scheme, well-matched to the expectedground conditions.  When selecting the construction site of a hydro dam, many factors are involved such as technical,social and environmental. In this paper we focus exclusively on the technical aspects that concern thepre-construction stages and the volume of direct and indirect exploration of the ground.  The purpose ofthe exploration is to obtain a geological model as clear as possible that serve to characterize thegeotechnical site and so the planning, budgeting and perform the structural design of the works as wellas obtain sufficient information to establish a safe and economic project.

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 Geological risk managementand its economic consequences can lead to major losses beyond the physical repair of the work whichrely on a good investigation of the site . Referring to geotechnical instrumentation and monitoringworks, Allen mentions difficult conditions to detect (with exploration methods) the presence of lensesmade of soft material, highly compressible areas and pockets of high pore pressure, which can causefaulting in the rock mass. From here, it is important to remark the need of the exploration as even forthe location of the monitoring zones must follow criteria based on direct or indirect examination.  Thiswork shall consider direct exploration of the site though drilling (exploratory boreholes), geotechnicaltesting of permeability in wells and excavations of galleries or tunnels. Drilling is a great support todefine the stratigraphic and structural model for the site and to identify basic geotechnical parametersfor design of the work, being carried out on both margins and the river bed, according to the location ofthe works.  The objectives of the sampling site with exploratory drills with core recovery usually includethe following: stratification on the site, vertical or lateral variations in subsurface geological conditions,sampling for laboratory testing, verification of the interpretation of geophysical measurements andplacement of instruments in situ for geotechnical, geophysical and geohydrological testing.  Theinterpretation of the evidence can be presented to anticipate areas of instability conditions.Geotechnical testing of permeability in the wells by injecting pressurized water constitute a substantialproportion of direct examination and focuses on the competition of the rock mass and its ability tofacilitate or prevent leakage of water from the dam. Natural disasters in India can be understood better and controlled well, if geology is understood well.Give your opinion about this statement using appropriate case studies.  Landslides are very common indeed in the Lower Himalayas. The young age of the region's hills resultin labile rock formations, which are susceptible to slippages.  Rising population and developmentpressures, particularly from logging and tourism, cause deforestation. The result is denuded hillsideswhich exacerbate the severity of landslides; since tree cover impedes the downhill flow of water.[3] Partsof the Western Ghats also suffer from low-intensity landslides.  Avalanches occurrences are common inKashmir, Himachal Pradesh, and Sikkim.Floods in India Floods are the most common natural disaster in India. The heavy southwest monsoonrains cause the Brahmaputra and other rivers to distend their banks, often flooding surrounding areas.  Though they provide rice paddy farmers with a largely dependable source of natural irrigation andfertilisation, the floods can kill thousands and displace millions.  Excess, erratic, or untimely monsoonrainfall may also wash away or otherwise ruin crops. Almost all of India is flood-prone, and extremeprecipitation events, such as flash floods and torrential rains, have become increasingly common incentral India over the past several decades, coinciding with rising temperatures. Meanwhile, the annualprecipitation totals have shown a gradual decline, due to a weakening monsoon circulation as a resultof the rapid warming in the Indian Ocean and a reduced land-sea temperature difference.

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 This meansthat there are more extreme rainfall events intermittent with longer dry spells over central India in therecent decades.  Cyclones in India Intertropical Convergence Zone, may affect thousands of Indians living in the coastalregions. Tropical cyclogenesis is particularly common in the northern reaches of the Indian Ocean inand around the Bay of Bengal. Cyclones bring with them heavy rains, storm surges, and winds thatoften cut affected areas off from relief and supplies.  In the North Indian Ocean Basin, the cycloneseason runs from April to December, with peak activity between May and November. Each year, anaverage of eight storms with sustained wind speeds greater than 63 kilometres per hour (39 mph) form;of these, two strengthen into true tropical cyclones, which have sustained gusts greater than 117kilometres per hour (73 mph).  On average, a major (Category 3 or higher) cyclone develops every otheryear.During summer, the Bay of Bengal is subject to intense heating, giving rise to humid and unstable airmasses that produce cyclones. Many powerful cyclones, including the 1737 Calcutta cyclone, the 1970Bhola cyclone, the 1991  Bangladesh cyclone and the 1999 Odisha cyclone have led to widespreaddevastation along parts of the eastern coast of India and neighboring Bangladesh. Widespread deathand property destruction are reported every year in exposed coastal states such as Andhra Pradesh,Orissa, Tamil Nadu, and West Bengal.  India's western coast, bordering the more placid Arabian Sea,experiences cyclones only rarely; these mainly strike Gujarat and, less frequently, Kerala.Intertropical Convergence Zone, may affect thousands of Indians living in the coastal regions. Tropicalcyclogenesis is particularly common in the northern reaches of the Indian Ocean in and around the Bayof Bengal. Cyclones bring with them heavy rains, storm surges, and winds that often cut affected areasoff from relief and supplies.  In the North Indian Ocean Basin, the cyclone season runs from April toDecember, with peak activity between May and November. Each year, an average of eight storms withsustained wind speeds greater than 63 kilometres per hour (39 mph) form; of these, two strengthen intotrue tropical cyclones, which have sustained gusts greater than 117 kilometres per hour (73 mph). Onaverage, a major (Category 3 or higher) cyclone develops every other year.  During summer, the Bay of Bengal is subject to intense heating, giving rise to humid and unstable airmasses that produce cyclones. Many powerful cyclones, including the 1737 Calcutta cyclone, the 1970Bhola cyclone, the 1991 Bangladesh cyclone and the 1999 Odisha cyclone have led to widespreaddevastation along parts of the eastern coast of India and neighbouring Bangladesh. Widespread deathand property destruction are reported every year in exposed coastal states such as AndhraPradesh, Orissa, Tamil Nadu, and West Bengal.  India's western coast, bordering the more placidArabian Sea, experiences cyclones only rarely; these mainly strike Gujarat and, less frequently, Kerala.In terms of damage and loss of life, Cyclone 05B, a supercyclone that struck Orissa on 29 October1999, was the worst in more than a quarter-century. With peak winds of 160 miles per hour (257 km/h),it was the equivalent of a Category 5 hurricane. Almost two million people were left homeless; another20 million people lives were disrupted by the cyclone. Officially, 9,803 people died from the storm;unofficial estimates place the death toll at over 10,100.

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LANDSLIDES.  The term landslide refers to the downward sliding of huge quantities of land masses. Suchsliding occurs along steep slopes of hills or mountains.. It may be sudden or slow in its occurrence. Also, in magnitude, it may be major or minor.Often, loose and unconsolidated surface material undergoes sliding. But sometimes, huge  blocks of consolidated rocks may also be involved.  If landslides occur in places of importancesuch as highways, railway lines, valleys, reservoirs, inhabited areas and agricultural lands leadsto blocking of traffic, collapse of buildings, harm to fertile lands and heavy loss to life andproperty. In India, landslides often occur in Kashmir, Himachal Pradesh and in the mountains of Uttar Pradesh. CLASSIFICATION OF EARTH MOVEMENTS: All movements of land masses are referred to aslandslides and grouped them under “earth movements”. The classification of earth movements us as follows: EARTH MOVEMENTS EARTH FLOWS  Solifluction  Creep LANDSLIDES  Debris slides and slump  Rock slides  Rock falls SUBSIDENCE  Compaction  Collapse Earth Flows:  There are three types of earth flows viz., solifluction; creep and rapid flows.Solifluction refers to the downward movement of wet soil along the slopes under the influenceof gravity.Creep refers to the extremely slow downward movement of dry surface material.  This is veryimp from the civil engg point of view due to slow movement of mass.  On careful examination,bending of strata ; dislodgement of fence posts ; telephone poles, curvature of tree trunks;broken retaining walls etc offer clues to recognize creep. Rapid flows  It is similar to creep but differ with reference to the speed. Rapid flows generallyaccompany heavy rains.  Mud flows are similar to rapid flows. Landslides  It is include Debris slides, rock slides and rock falls.  Debris slides are common along the steep sides of rivers, lakes.  Debris slides of small magnitude are called slumps.  Rock slides are the movements of consolidated material which mainly consists of recentlydetached bedrocks.  For eg: a rock slide that took place at Frank, Alberta in 1903 killing 70people.Rock falls refer to the blocks of rocks of varying sizes suddenly crashing downwards alongsteep slopes. These are common in the higher mountain regions during the rainy seasons. Subsidence  It is compaction of underlying material or due to collapse.  Subsidence due to compaction: Sediments often become compact because of load.

D.ANJALA/AP/CIVIL CE6301 ENGINEERING GEOLOGY VTHT

 Excessive pumping out of water and the withdrawal of oil from the ground also cause subsidence. Subsidence due to collapse: In regions where extensive underground mining has removed alarge volume of material, the weight of the overlying rock may cause collapse and subsidence. CAUSES OF LANDSLIDES: Landslides occur due to internal causes (inherent). The internalcauses are again of various types such as Effect of slope; Effect of water; Effect of Lithology;Effect of associated structures ; Effect of human factors etc.. 1.Effect of slope: This is a very important factor which provides favourable conditions for landslide occurrence.Steeper slopes are prone to land slips of loose overburdens due to gravity influence.However, it should be remembered that hard consolidated and fresh rocks remain stable evenagainst any slope.

2.Effect of water:  The presence of water greatly reduces the intergranular cohesion of theparticles of loose ground causing weakness of masses and prone to landslide occurrence.  Water, being the most powerful solvent, not only causes decomposition of minerals but also  leaches out the soluble matter of rocks.  This reduces the compaction of rock body and makes it a weak mass.

3.Effect of Lithology;  Rocks which are highly fractured, porous and permeable are prone tolandslideoccurrence because they give scope for the water to play an effective role.  In addition,rocks which contain clay minerals, mica calcite, glauconite, gypsum etc are more prone tolandslide occurrence because, all these minerals are easily leached out.

4.Effect if associated structures ;  The geological structures such as bedding planes,joints,faults or shear zones are planes of weakness and cause landslide occurrence.

5.Effect of human factors:  Human beings sometimes, interfere with nature by virtue of their activities and cause landslides. For eg: laying roads ; railway tracks etc..  When construction works are carried out on hill tops, the heavy loads on the loose zone of overburden create a sliding of rock masses.

D.ANJALA/AP/CIVIL