Plate Tectonics

• Plate tectonics explains the movement of Earth's lithosphere over the asthenosphere.
• Earth's lithosphere is divided into large, rigid plates that float on the semi-fluid asthenosphere.
• The movement of tectonic plates causes earthquakes, volcanic activity, mountain formation, and the distribution of continents and oceans.

Plate Tectonics and Plate Movements

• Plate tectonics involves the movement of Earth's lithospheric plates over the malleable asthenosphere.
• Divergent plate movement results in plates moving apart, creating new crust, such as at mid-ocean ridges.
• Convergent plate movement: Plates move toward each other, often leading to subduction zones.
• Subduction occurs when one plate is forced beneath another, common in oceanic-continental collisions.
• Transform plate movement involves plates sliding past each other horizontally, exemplified by the San Andreas Fault.

Plate Boundaries

• Divergent boundaries: Plates move away from each other, like at the mid-Atlantic Ridge.
• Convergent boundaries: Plates move towards each other, forming mountains or causing subduction, such as in regions with the Himalayas and the Mariana Trench.
• Transform boundaries: Plates slide past each other horizontally, such as along the San Andreas Fault.

Continental Drift and Seafloor Spreading

• Continental Drift, proposed by Alfred Wegener, suggests continents were once part of Pangaea.
• Continents drifting apart is supported by matching coastlines, similar fossils on distant continents, and geological similarities.
• Seafloor Spreading, proposed by Harry Hess, explains new oceanic crust creation at mid-ocean ridges through volcanic activity.
• New crust formation pushes older crust away, supporting plate movement.

Earthquake Disaster Risk Reduction

• Earthquake disaster risk reduction minimizes earthquake impacts.
• Key measures include building earthquake-resistant infrastructure.
• Implementation of early warning systems helps prepare for earthquakes.
• Emergency preparedness and education are crucial for saving live.
• Land-use planning helps avoid construction in high-risk zones, such as near active faults.
• Post-earthquake response and recovery efforts are vital for rebuilding.

Rocks and Minerals

• Rocks are solids composed of one or more minerals, classified as igneous, sedimentary, and metamorphic.
• Minerals are naturally occurring, inorganic solids, having a specific chemical composition and crystalline structure, e.g., quartz and feldspar.

Properties of Minerals

• Color: The mineral's external color, though not always reliable.
• Hardness: Measured by the Mohs scale of hardness.
• Luster: How a mineral reflects light (metallic, non-metallic, etc.).
• Cleavage/Fracture: The way a mineral breaks.
• Streak: The color of a mineral's powdered form.
• Density: Mass per unit volume.

Economic Importance of Minerals

• Minerals are raw materials for various industries.
• Metals are economic in manufacturing, construction, and technology (e.g., iron, copper, gold).
• Industrial minerals are economic in construction and manufacturing (e.g., limestone, gypsum).
• Precious stones are economic in jewelry and ornamental products (e.g., diamonds, rubies).

Igneous Rocks

• Igneous rocks form from the cooling and solidification of magma or lava.
• Intrusive (Plutonic) igneous rocks form inside the Earth, such as granite.
• Extrusive (Volcanic) igneous rocks form from lava on the Earth's surface, such as basalt.

Sedimentary Rocks

• Sedimentary rocks are formed by the accumulation and compaction of sediments (e.g., sand, clay).
• Clastic sedimentary rocks are formed from fragments of other rocks (e.g., sandstone).
• Chemical sedimentary rocks are formed from the evaporation of water (e.g., limestone).
• Organic sedimentary rocks are formed from the remains of living organisms (e.g., coal).

Metamorphic Rocks

• Metamorphic rocks form when existing rocks (igneous, sedimentary) are subjected to high pressure, heat, or chemically active fluids.
• Foliated metamorphic rocks exhibit a layered appearance like slate and schist.
• Non-foliated metamorphic rocks do not have a layered structure, such as marble and quartzite.

Rock Properties and Identification

• Rocks are identified based on texture, mineral composition, and formation process.
• Rock characteristics such as color, grain size, and pattern help geologists classify them.

Rock Cycle

• The rock cycle is a continuous process where rocks are formed, broken down, and transformed into other types.
• Igneous rocks form from cooling magma.
• Sedimentary rocks form from the erosion and deposition of particles.
• Metamorphic rocks form from the transformation of existing rocks under heat and pressure.

Soil Types

• Clay soil: Fine-grained, retains water but drains poorly.
• Sandy soil: Coarse, drains quickly but has low fertility.
• Loamy soil: A mixture of sand, silt, and clay, ideal for most plants.
• Peaty soil: Rich in organic material and retains moisture.
• Saline soil: Contains high levels of salts and is poor for most crops.

Soil Profiling

• Soil profiling refers to the vertical section or "profile" of the soil, revealing different layers or horizons.
• O Horizon: Organic layer, rich in decomposed material.
• A Horizon: Topsoil, rich in minerals and organic material.
• B Horizon: Subsoil, accumulation of minerals leached from the topsoil.
• C Horizon: Weathered parent material (rock).
• R Horizon: Bedrock.