Preface During my long teaching experience, I felt that geology is a new subject for beginners. The undergraduate students of this stream are deprived of concise and comprehensive text book particularly on principles and practical aspects of geology. They have no other option than to go through numerous text books on different branches of geology and are often confused as to how much they should read and write, it leads to wastage of time and energy. With this objective in view, I have written this book entitled “Geology: Principles and Practical Manual”. An attempt has been made to discuss the fundamental principles of different branches of geology prescribed in the syllabus, so that the students acquire basic knowledge of the subject. The book contains 8 chapters, viz. Geomorphology, Geological Maps, Crystallography, Mineralogy & Petrology, Palaeontology, Stratigraphy, Structural Geology and Economic Geology, Remote Sensing & Photogeology. Each chapter consists of specific branch of geology and deals with the principles and then its practical aspects. Chapter-1, Geomorphology deals with definition and introduction of different natural processes of landforms, and then practical exercises on different geomorphological models with labelled figures and precise descriptions. Chapter-2, Geological Maps deals with different terminologies used in geological map like contour line, outcrop, dip, strike etc. Different practical exercises with some solutions on geological maps: three point problem and cross section map, so that students can learn how the maps are prepared and interpreted. Chapter-3, Crystallography contains basic terminologies, symmetry elements and different crystal systems etc. which will be helpful in identification of crystals. Crystals of important minerals with their faces and Miller's symbols and figures are also incorporated in this chapter. Minerals and Rocks are dealt in Chapter-4, it comprises physical and optical properties of important rock forming minerals with coloured photos and photomicrographs. In petrology section, characteristic properties of all the rock types (Igneous, Sedimentary and Metamorphic) have been described briefly in tabular form with coloured diagrams; it would be of great help to the students to identify different rocks during practical exercises. Chapter-5, Palaeontology contains brief description on modes of fossil preservation and description of fossils from different phylum including plant fossils, their classification morphology and geological age with diagrams. Chapter-6, Stratigraphy covers principles, classification and stratigraphic correlation. It also contains Physiographic divisions of India, Geological Time Scale, and Indian stratigraphy from Archaeans to Dharwar to the Siwalik Formation with their geological successions and distribution in the map of India. Chapter-7, Structural Geology deals with identification and description of structural features including the primary sedimentary features like bedding, cross bedding etc. their attitude (strike and dip), unconformity, joints and the diastrophic structures like fold and fault with block diagrams. The last Chapter8, Economic and Ore Geology, Remote sensing and Photogeology consists of basic concepts and practical aspects of these subjects as prescribed syllabus of B.Sc./ B.E. Civil and Mining Engineering courses in various Universities and Institutes. Since this is my first effort, there ought to be several mistakes and shortcomings. The critical evaluation and suggestions by the learned readers will be wholeheartedly welcome, which will go towards the improvement of this book .

1.1 Geomorphology Geomorphology is the scientific study of the origin and evolution of topographic and bathymetric features created by physical or chemical processes operating at or near the earth's surface. The surface of the earth is unstable and affected by a combination of surface and geologic processes that cause tectonic uplift and subsidence. Surface processes are mainly physical and chemical action of water, wind, ice, igneous activity and activities of living organisms on the surface of the earth. Upliftment of mountain ranges, the growth of volcanoes, isostatic changes in surface elevation and formation of deep sedimentary basins are categorized under Geological processes. Main geomorphological processes occurring in nature are as follows: 1.1.1 Aeolian processes Aeolian processes include activities of the winds, its ability to shape the surface of the earth. Wind acts as an effective agent of erosion, transportation and deposition materials, and large supply of fine, unconsolidated sediments. Aeolian processes are important in desert (arid) environments. 1.1.2 Fluvial processes Moving water in a river channel, is able to mobilize sediment and transport it downstream. The rate of sediment transport depends on the availability of sediment itself and the discharge by river. River originates from mountain with V shaped valley, which later increases in size, merging with other rivers. The network of rivers thus formed is known as drainage system. These systems show four general patterns viz. dendritic, radial, rectangular, and trellis etc. In the mature stage, the river form alluvial flood plains, meanders and ox-bow lakes. Finally when it merges to ocean, forms delta.

2.1 Introduction Topographic expression is the replica of geological structures present within the earths surface. When various types of rocks of an area are displayed on a map (sheet of paper), it is known as Geological Map. Normally geological maps prepared on topographic maps. Surface topography is best presented by contour lines on a plain paper. The importance of geological maps is to understand the nature of structure and distribution of surface outcrops with their relation to contour lines. Horizontal and dipping beds are easily identified on map because, horizontal beds runs parallel to contour lines while inclined beds cut through different contours. The angle and direction of dip can be calculated from geological maps. Geological maps are of great importance to civil engineers, after studying geological maps and consultation with geologists, civil engineers can advice for construction of engineering structures like excavation of road cuttings and construction of canal, bridges, dams and tunnels etc. Geologists get vital clues about the geological history of an area, and can draw a cross section of an area and know the structure present underground.

3.1 Introduction Crystallography is the science of crystals. The term crystal is derived from the Greek word “Crystallos” which means “ice”. The term was used for colorless quartz which was believed to be “fossilized” ice. Crystals are bodies bounded by flat surface, arranged on a definite plan which is an expression of the internal arrangement of the atoms. They are formed by consolidation of magma which is also considered as crystallization. 3.2 Terms in Use to Describe a "Crystal" 3.2.1 Faces Faces are the plane surface in a crystal. The common faces are usually parallel to net planes containing the greatest number of lattice points or ions. Wide spacing between the net planes leads to development of faces in these planes. Faces are two types like and unlike faces.

The earth's crust is made up of minerals and rocks. Minerals are inorganic substances with a definite chemical composition, whereas rocks are mixture or aggregates of minerals. Each mineral is composed of certain elements present in fixed proportion. For example, mineral quartz, SiO2 is a compound of the elements silicon (Si) and oxygen (O) combined in the proportion of 1:2, so its chemical formula is SiO2, whereas rock granite is a mixture of several minerals like quartz, feldspar etc. Nature has provided unique physical properties to different minerals that can be used to identify them. 4.1 Physical Properties of Minerals Majority of minerals contain following properties that can be used to identify them in field and in laboratory: crystal habit, cleavage, hardness, density, luster, streak, color, tenacity, magnetism, and taste. 4.1.1 Crystal habit The faces that develop on a crystal depend on the space available for the crystals to grow. If crystals grow into one another or in a restricted environment, it is possible that no well-formed crystal faces will be developed. However, crystals sometimes develop certain forms more commonly than others, although the symmetry may not be readily apparent from these common forms. The term used to describe general shape of a crystal is habit. Some common crystal habits are as follows:

The remains of animals and plants of past ages preserved in the rocks are known as fossils, the study of which forms the subject of Palaeontology. The conditions for an animal or plant to become a fossil are firstly it must possess skeleton of some kind or some hard parts, since the soft parts are decomposed rapidly, secondly the organism must be covered up by sedimentary layer, otherwise it will soon crumble to pieces. 5.1 Modes of Preservation of Fossils The conditions in which fossils occur depends, on their original composition and on the material in which they are embedded. The chief types are as follow: 5.1.1 The entire organism preserved Occasionally the soft parts of the organism are preserved as well as the skeleton, the whole having suffered very little change. Instances of this are the woolly rhinoceros and mammoth found frozen in the mud and ice in Northern Siberia. Insects encased in fossil resin, known as amber, are found in the Oligocene beds in the Baltic shores of Persia, but the soft part of organisms are rarely preserved. 5.1.2 The skeleton preserved almost unchanged Sometimes where the skeleton alone is preserved, it remains almost in its original condition, except that it has lost its organic matter. Thus the shells in the Pliocene beds of England differ from living ones only in being lighter, more porous and generally colourless. In some instances a certain amount of mineral matter, such as carbonate of lime, has been added to the skeleton, making it heavier and more compact.

6.1 Introduction Stratigraphy is the branch of geology which deals with the study of rock layers (strata) and layering (stratification) in their chronological order. It is primarily used in the study of sedimentary and layered volcanic rocks in order to interpret geological history and age. The term historical geology is also used as a synonym of stratigraphy but in a wider sense, it deals with the whole sequence of events that make up the history of the earth from its origin and age relations of rock strata, evolution through its life form, and structures. The scope of stratigraphy is very wide; it involves description and classification of layered sedimentary rocks and also of igneous & metamorphic rocks. The study involves correlation between different areas like lithological characters, fossil content, geophysical and geochemical properties including absolute radiometric dating. 6.2 Principles of Stratigraphy Stratigraphy is based on the following few principles: 6.2.1 Law of superposition In a sequence of horizontal sedimentary rock layers, the younger layers are on the top and the older layers are at the bottom. To put it another way, in a normal sequence, each bed is younger than the bed beneath it. Geologists today use it as the basis for a bed-by-bed analysis of geological history in a given area. This is important to stratigraphic dating, which assumes that an object cannot be older than the materials of which it is composed. This law known as "Law of Superposition" was first proposed by the scientist Nicolas Steno in the 17th century.

7.1 Introduction The earth's crust is made up of igneous, sedimentary and metamorphic rocks. Each variety of rocks exhibit some columnar joints in Igneous rock, characteristic structures like bedding in sedimentary rocks and fabrics like schistosity and gneissosity in metamorphic rocks. As a result of tectonic activities in nature, rocks may suffer deformation, rupture, dislocation of beds (Fault) or other planar structures.. The whole study of such deformation is known as structural Geology. It has been observed that sedimentary rocks are most suitable for studying structures, because these rocks are deposited in quiet environment, and initially the beds arranged in horizontal position. As a result of stress due to kinematic movements/tectonism, the horizontal beds tend to deviate from their horizontal disposition to dipping position or get folded or faulted. Thus the rock develops various kinds of structures. There are following structures present in sedimentary rocks:

8.1 Economic Geology and Ore Mineralogy 8.1.1 Economic geology Economic Geology deals with the comprehensive study of mineral deposits including their processes of formation and uses. By applying the principles of geology, a mining engineer is able to exploit such deposits profitably for the use of Man. 8.1.2 Ore mineral An ore is a term applied usually to that part of a metalliferous mineral deposit that can be utilized profitably as a source of one-or-more metals, this term now is widely used for the usable part of many non-metallic (non-metalliferous mineral) deposits, like barite, fluorite, sulphur, etc. 8.1.3 Gangue mineral An ore is usually a mixture of one or more usable minerals (ore minerals) and one or more unusable minerals (gangue minerals). The usual gangue minerals are quartz and other forms of silica, calcite, dolomite, siderite, barite, feldspars, garnet, chlorite, kaolin, fluorite, apatite, pyrite, pyrrhotite, arsenopyrite, and sometimes the gangue material is the country rock or host rock itself in which the ore minerals occur. Sometimes, the gangue minerals may also be utilized as by-products of the ore deposit. The nature and proportion of the gangue influence the economic value of an ore to a great extent.

Acknowledgement Getting this book into your hands was a joint effort. I acknowledge the contributions of my colleagues, students and reviewers who helped in deepening my learning for the book “Geology: Principles and Practical Manual”. Sincere thanks to all the reviewers who helped me to improve the book with their incisive comments. And finally, a very special thanks to my wife Dr Arti and lovely children Abhishek and Anilabh, for being a constant source of motivation and encouragement. I also acknowledge the following books and internet links that helped me in completing this huge task: