ELS reviewer - sycip.pdf

Characteristics of the Earth ❖ Earth is a terrestrial an ocean planet ❖ Only the habitable planet ❖ Water cover’s 70% of the surface ❖ Composed of nitrogen and oxygen Comparison to Venus and Mars ★ Venus - earth’s twin ★ Mars - half size of the earth Factors that make the Earth habitab...

Characteristics of the Earth ❖ Earth is a terrestrial an ocean planet ❖ Only the habitable planet ❖ Water cover’s 70% of the surface ❖ Composed of nitrogen and oxygen Comparison to Venus and Mars ★ Venus - earth’s twin ★ Mars - half size of the earth Factors that make the Earth habitable ➔ Temperature ➔ Water ➔ Atmosphere ➔ Nutrients ➔ Energy Subsystems of the Earth ➔ Geosphere (land) - Rocks and minerals ➔ Hydrosphere (water) - Liquid ➔ Atmosphere (air) - Gases ; oxygen and nitrogen ➔ Biosphere (life) - All living organisms Layers of the Earth - Crust - Mantle - Outer Core - Inner Core Rocks and Minerals Mineral - A mineral is an element or chemical compound that is normally crystalline and that has been formed as a result of geological processes. Requirements by geoglogists : 1. Homogeneous solid 2. Inorganic 3. Naturally occurring 4. Definite chemical composition 5. Ordered Internal Structure Physical Properties of Minerals 1. Color or streak - Streak : powdered form 2. Luster - Ability to reflect light 3. Hardness - Softest : Talc ;; Hardest : Diamond 4. Cleavage - Smooth, flat surfaces Chemical Composition of Minerals Silicate - Silicon and oxygen Oxides - Used for paint industry Sulfates - Sulfur and oxygen Sulfides - Sulfur and metal Carbonates - Carbonate Native Elements Halides - Halogens Types of Rocks ★ Igneous Rocks - solidification of molten material ➔ Plutonic (Intrusive) - below the surface/magma  ➔ Volcanic (Extrusive) - at the surface/lava ★ Sedimentary Rocks - Accumulation, Compaction, and Cementation ★ Metamorphic Rocks - pre-existing rock undergoes metamorphism Weathering, Erosion, Decomposition - Endogenic (Under) - Exogenic (On the surface) Weathering - process of break down of rocks into sediments - No movement involved Types of Weathering 1. Mechanical (Physical) Pressure Temperature - Rocks expands at high temperature Frost wedging - Water accumulates on the cracks Abrasion - Impact and Friction Organic Activity Human activities Burrowing 2. Chemical Dissolution - Minerals dissolved in water Hydrolysis - React with water Oxidation - Response of oxygen to minerals Erosion - Soil or rock particles are moved elsewhere through a transporting agent Agents of Erosion - Gravity - Wind - Water - Glacier - river of ice Earth’s sources of heat 1. Primordial 2. Radiogenic Primordial Heat “Existing from the beginning” - Accretion and bombardment Homogeneous Accretion - Similar elements stick together creater a solid mass Heavier elements sink in the center because of gravity Radiogenic Heat - long term radioactive decay (K40, Th232, U235, U238) Magma - formed when rocks are melted. Heat Transfer - movement of thermal energy to a cooler one. Mantle Convection - slow movement of earth’s solid mantle due to convection currents. Main way heat from earth’s interior is transported to its surface. ★ Conduction - heat transfer to solids (colliding molecules) ★ Convection - heat transfer to liquids (occurs in the mantle) ★ Radiation - heat transfer from the sun Magma Formation ❖ Magma - hot liquid and semi-liquid rock under the surface of the earth ❖ Lava - when magma moves or erupts Three components of magma/lava 1. Melts 2. Solids 3. Volatiles Basic Types of Magma 1. Basaltic 2. Andesitic 3. Rhyolitic - Higher viscosity, higher temperature, lighter color Types of melting ❖ Decompression melting - occurs on mid-ocean ridges ➔ Pressure decreases, causes melting point to drop, melts the material ❖ Flux-melting - occurs on subduction zones ➔ Water is added to the rock, melts the material ❖ Heat-induced Melting - occurs on hotspots ➔ Heat is applied, melts the material ❖ Partial Melting - mantle does not melt uniformly, some remains as solids Classification of Igneous Rock according to texture ★ Phaneritic - large interlocking crystals ★ Aphanitic - fine-grained (not visible) ★ Porphyritic - phenocrysts (large crystals) ★ Vesicular - contains holes or pores ★ Glassy - non-crystalline (no mineral grains) Obsidian - pure volcanic glass Metamorphism - changes takes place within a body of a rock. Meta : to change ;; Morph : Form Metamorphic grade - pertains to the temperature and/or pressure condition(s) to which a rock has been subjected during metamorphism. ➔ Foliated Metamorphic Rock - parallel arrangement of certain mineral grains that gives the rock a striped appearance. ➔ Foliation forms when pressure squeezes the flat or elongate minerals within a rock so they become aligned. ➔ Non-foliated Metamorphic Rock - do not have a platy or sheet-like structure.composed of a mosaic of roughly equidimensional and equigranular minerals. Faults and Folds Kinds of Stress 1. Compression stress - stress causes rocks to compress 2. Tension Stress - stretch causes rocks to stretch 3. Shearing stress - stress applies in opposing directions 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. Parts of a Fold Limbs - the sides or flanks Axial plane - imaginary line that separates the fold into two Hinge line/fold axis - line dividing the fold Anticline - fold arching upward Syncline - fold arching downward ➔ Overfolds - more than 90 degrees ➔ Recumbent Folds - Horizontal axial plane ➔ Fault - Fracture between rocks ➔ Creep - slow mass movement Parts of a Fault - Fault plane : where action occurs  - Fault trace - line on the surface - Hanging wall - when fault is slopping - Foot wall - when fault is vertical Types of fault ★ Normal fault - created by tension ★ Reverse fault - created by compression ★ Strike-slip fault - created by shearing Layers of Rock Nicholas Steno - studied positions of sedimentary rock Strata - also known as rock layers Stratigraphy - science of strata Law of superposition - any location indicates the ages of rock layers Law of original horizontality - most sediments were layed down horizontally Principle of lateral continuity - layers of sediments extends laterally in all directions Principle of cross-cutting - geologic feature which cuts another is the younger of the two features. ❖ Relative Dating - Relative order or past events; estimate age of rocks but not the ❖ actual age ❖ Absolute Dating - Determining age of rocks in a specified timescale. Radiometric Method - process where it determines the number decaying products such as isotopes. Half-life - time required for one-half of nuclei of the isotope to decay