Midterm Reviewer PDF

**MIDTERM REVIEWER** **1. General Geology & Earth Processes** - **Geology**: Study of the Earth, its structure, composition, and the processes that have shaped it over its 4.5 billion-year history. - **Earth**: Third planet from the Sun, the only planet known to support life, with 70....

**MIDTERM REVIEWER** **1. General Geology & Earth Processes** - **Geology**: Study of the Earth, its structure, composition, and the processes that have shaped it over its 4.5 billion-year history. - **Earth**: Third planet from the Sun, the only planet known to support life, with 70.8% oceanic crust and 29.2% land. **Earth Processes:** - **Exogenic (External)**: Weathering, erosion, transportation, and deposition, all driven by solar energy and gravity. - **Endogenic (Internal)**: Driven by Earth\'s internal heat, responsible for tectonic activity, volcanism, mountain building, and earthquakes. **Key Earth Processes:** - **Plate Tectonics**: The movement of Earth's lithospheric plates causing earthquakes, volcanic activity, and mountain formation. - **Continental Drift**: Theory that continents have moved over geological time to their current locations. **2. Petrology & Rock Types** - **Petrology**: Study of rocks, including their composition, structure, and formation processes. - **Petrography**: A sub-discipline focusing on the description and classification of rocks. **Types of Rocks:** 1. **Igneous Rocks**: Formed from solidification of molten magma. Examples include: - **Intrusive (Plutonic)**: Formed below the Earth's surface (e.g., granite). - **Extrusive (Volcanic)**: Formed from lava erupted onto the surface (e.g., basalt). 2. **Sedimentary Rocks**: Formed from the accumulation and compaction of sediments. - **Clastic**: Formed from fragments of other rocks. - **Organic**: Formed from the remains of living organisms. - **Chemical**: Precipitated from mineral-rich solutions. 3. **Metamorphic Rocks**: Formed from pre-existing rocks altered by heat, pressure, or chemical processes (e.g., marble, schist). **Rock Cycle: The continuous transformation of rocks from one type to another driven by Earth's internal and external processes.** **3. Weathering** - **Weathering**: The breakdown of rocks into smaller particles through physical, chemical, and biological processes. **Types of Weathering:** - **Physical/Mechanical Weathering**: Breakdown of rocks through physical processes like temperature changes, freeze-thaw cycles, and root growth. - **Chemical Weathering**: Involves chemical reactions like oxidation, hydrolysis, and carbonation that alter the composition of rocks. - **Biological Weathering**: Caused by plants, animals, and microbes, such as roots breaking rocks or lichen secreting acids. **4. Soil Formation & Types** - **Soil**: The upper layer of Earth where plants grow, consisting of organic material, clay, rock particles, and minerals. **Soil Horizons:** - **O Horizon**: Organic layer, rich in decomposed material. - **A Horizon**: Topsoil, a mix of organic matter and minerals. - **B Horizon**: Subsoil, contains minerals leached from above. - **C Horizon**: Weathered parent material. - **R Horizon**: Bedrock. **Types of Soil:** - **Sandy Soil**: Coarse texture, good drainage but poor nutrient retention. - **Clay Soil**: Fine particles, retains water but has poor drainage. - **Silt Soil**: Smooth texture, good water retention and nutrient capacity. - **Loamy Soil**: A balanced mix of sand, silt, and clay, excellent for plant growth. **5. Soil Erosion & Control Measures** - **Soil Erosion**: The displacement of soil by water, wind, or human activity. **Types of Soil Erosion:** 1. **Water Erosion**: Rainfall and surface runoff wash away soil. 2. **Wind Erosion**: Common in arid regions, where wind blows away topsoil. **Prevention Methods:** - **Terracing**: Creating step-like ridges on slopes to slow water runoff. - **Windbreaks**: Planting trees to reduce wind speed and protect soil. - **Cover Cropping**: Planting crops that protect soil from erosion between harvests. - **Conservation Tillage**: Reducing the frequency and intensity of soil disturbance. **6. Landslides & Preventive Engineering** - **Landslide**: The movement of rock, soil, or debris down a slope due to gravity. **Causes of Landslides:** - **Heavy Rainfall**: Saturates soil, reducing its stability. - **Geological Factors**: Weak rock formations and steep slopes. - **Human Activities**: Deforestation, construction, and mining increase the risk. - **Earthquakes**: Ground shaking can trigger landslides. **Prevention:** - **Retaining Walls**: Stabilize soil on slopes. - **Soil Nailing**: Reinforce unstable slopes with nails or rods. - **Drainage Systems**: Prevent water buildup that weakens slopes. - **Shotcrete**: Sprayed concrete used to cover and stabilize slopes. **7. Soil Testing & Analysis for Engineering** - **Soil Boring Tests**: Used to assess soil composition, strength, and moisture content before construction. **Key Tests:** - **Standard Penetration Test (SPT)**: Determines soil density and strength. - **Plate Load Test**: Direct measurement of soil bearing capacity. - **Triaxial Test**: Measures soil shear strength and deformation. - **Direct Shear Test**: Assesses soil resistance to sliding. **Soil Properties:** - **Liquid Limit (LL)**: Moisture content where soil behaves like a liquid. - **Plastic Limit (PL)**: Moisture content where soil can be molded without cracking. - **Plasticity Index (PI)**: Range of moisture content over which soil remains plastic. **8. Soil Compaction & Density Tests** - **Compaction**: The process of increasing soil density by removing air pockets. **Compaction Tests:** - **Proctor Test**: Determines the maximum dry density and optimal moisture content for soil compaction. - **Nuclear Density Test**: Measures soil density and moisture using gamma radiation. **Other Methods:** - **Sand Cone Test**: Measures the in-place density of compacted soil. - **Dynamic Cone Penetrometer (DCP)**: Assesses soil strength and suitability for foundation construction. **Study Tips:** 1. **Understand Key Concepts**: Focus on definitions and processes such as weathering, soil erosion, and the rock cycle. 2. **Memorize Rock Types**: Know examples and characteristics of igneous, sedimentary, and metamorphic rocks. 3. **Practical Applications**: Relate topics like soil testing and compaction to civil engineering projects. 4. **Revise Diagrams**: Familiarize yourself with diagrams of the rock cycle, soil horizons, and weathering processes. This covers the key topics between pages 7 to 117 of your document. Reviewing these sections will help you prepare thoroughly for your midterm exam.