Earth and Life Science (Core) - Week 2 PDF

SAINTS JOHN AND PAUL EDUCATIONAL FOUNDATION INC We teach, we train, we transform Subject matter: Earth and Life SCIENCE (Core) WEEK 2 TOPICS: I. Rocks and minerals 1. Categories of rocks. 2. The origin and environment of formation of comm...

SAINTS JOHN AND PAUL EDUCATIONAL FOUNDATION INC We teach, we train, we transform Subject matter: Earth and Life SCIENCE (Core) WEEK 2 TOPICS: I. Rocks and minerals 1. Categories of rocks. 2. The origin and environment of formation of common minerals and rocks. (rock cycle) II. Exogenic Processes 3. Geologic processes that occur on the surface of the Earth such as weathering, erosion, mass wasting, and sedimentation (include the role of ocean basins in the formation of sedimentary rocks). CONTENTS: A. ROCKS AND MINERALS Rocks are composed of 2 or more minerals or substances. They are similar to minerals in that they must be solid and occur naturally. Rocks are different in that they can be organic (or inorganic), they can have a crystalline structure but they do not always have one, and they have no specific chemical formula (they are mixtures of many formulae). Mineral Mineral is a naturally occurring and inorganic solid. Have a definite chemical composition and a crystalline structure. The earth is composed of mineral elements, either alone or in a myriad of combinations called compounds. A mineral is composed of a single element or compound. Minerals are the fundamental components of rocks. They are naturally occurring inorganic substances with a specific chemical composition and an orderly repeating atomic structure that defines a crystal structure, such as feldspar, quartz, mica, halite, calcite, and amphibole. Silicate minerals are the most abundant components of rocks on the Earth's surface, making up over 90% by mass of the Earth's crust. The common non-silicate minerals, which constitute less than 10% of the Earth's crust, include carbonates, oxides, sulfides, phosphates and salts. A few elements may occur in pure form. These include gold, silver, copper, bismuth, arsenic, lead, tellurium and carbon. Rocks A rock is a natural substance composed of solid crystals of different minerals that have been fused together into a solid lump. The minerals may or may not have been formed at the same time. What matters is that natural processes glued them all together. Example: Granite, basalt, sandstone, limestone, and schist. Geological Classification of rocks according to Characteristics such as 1. mineral and chemical composition, 2. permeability, 3. the texture of the constituent particles, 4. and particle size. These physical properties are the end result of the processes that formed the rocks. Over the course of time, rocks can transform from one type into another, as described by the geological model called the rock cycle. These events produce three general classes of rocks : igneous , sedimentary, and metamorphic Three main classification of rock Igneous: Igneous rocks form from the cooling of melted rock (either lava or magma) into solid form. If the cooling occurs underground, the rock is an intrusive, or plutonic, igneous rock. If the cooling occurs on the earth's surface, the rock is an extrusive or volcanic rock. Molten material within the Earth is called magma; it is ―lava‖ once it has erupted onto the surface. Metamorphic: from transformation of pre- existing rocks through the process of metamorphism. Metamorphism involve change in the physical and chemical properties of rocks in response to heat, pressure, and chemically active fluids. Sedimentary: Sedimentary rocks are either detrital or chemical. a. Detrital rocks are formed by the compaction of separate particles, or sediments, into a rock. b. Chemical sedimentary rocks form from minerals that have been dissolved in water and precipitate out, forming a solid rock. Geologists describe sedimentary rocks according to the size and shape of the particles in them or their mineral composition (in the case of chemical sedimentary rocks). Rock cycle The rock cycle is a basic concept in geology that describes transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous. Each rock type is altered when it is forced out of its equilibrium conditions. Each of these rocks are formed by physical changes—such as melting, cooling, eroding, compacting, or deforming—that are part of the rock cycle. How rock type can be changed? Rock can be changed through the processes of weathering, heating, melting, cooling, and compaction. Any one rock type can be changed into a different rock type as its chemical composition and physical characteristics are transformed. The minerals and metals found in rocks have been essential to human civilization. Rock Forming Minerals: The physical properties of minerals, such as their hardness, lustre, color, cleavage, fracture, and relative density can be used to identify minerals. Oxygen (O) 46.6% Calcium (Ca) 3.6% Silicon (Si) 27.7% Sodium (Na) 2.8% Aluminum (Al) 8.1% Potassium (K) 2.6% Iron (Fe) 5.0% Magnesium (Mg) 2.1% These general characteristics are controlled mainly by their atomic structure (crystal structure). Common rock-forming minerals: These are specimens of minerals from the University of Auckland's collection. Along with the common rock-forming minerals, including apatite, corundum, diamond, fluorite, topaz and talc to illustrate minerals used in Moh's Scale of Hardness. Classification and Identification of Minerals Minerals are classified according to their chemical composition. 1. Definite fixed composition, Quartz is always SiO2, and calcite is always CaCO3. 2. Form both by inorganic and organic processes. For example, calcite (CaCO3) is a common vein mineral in rocks, and also a shell-forming material in many life forms. Calcite of organic origin conforms to the above definition except for the requirement that it be inorganic. 3. "Mineraloids" While not truly falling into the category of minerals, they are still usually classified as minerals. Two well-known examples are Mercury, which lacks a crystal structure due to its liquid state, and Opal, which also lacks a crystal structure as well as a definitive chemical formula. Despite the fact that these mineraloids lack certain essential characteristics of minerals, they are classified as minerals in most reference guides including the acclaimed Dana's System of Mineralogy. 4. Organic minerals is another unique category of minerals. While this term is technically an oxymoron, since the definition of a mineral requires it to be inorganic, there are several naturally occurring rare organic substances with a definitive chemical formula. The best example of this is Whewellite. Most reference guides and scientific sources make an exception to these substances and still classify them as minerals. B. Exogenic & Endogenic process Exogenic Processes A process that occurring on the surface of the Earth that reduces relief, such as weathering, erosion, mass wasting, and sedimentation. Weathering Weathering is the decomposition and disintegration of rocks and minerals at the Earth’s surface. Erosion Erosion is the removal of weathered rocks and minerals by moving water, wind, glaciers and gravity. The four processes – weathering, erosion, transportation and deposition work together to modify the earth’s surface. Mechanical weathering Also called physical weathering and disaggregation, causes rocks to crumble. Water, in either liquid or solid form, is often a key agent of mechanical weathering. For instance, liquid water can seep into cracks and crevices in rock Abrasion- wearing-away of rocks by constant collision of loose particles. Sand and other rock particles carried by wind, water, or ice can wear away exposed surface of rocks. Can either be wind or water abrasion. Frost wedging – when water gets inside the joints, alternate freezing and thawing episodes pry the rocks apart. Salt crystal growth - Crystal growth often occurs when groundwater moves into empty pores or spaces of rock by capillary action. As the water evaporates, salt crystals grow and accumulate, putting pressure on the rock and causing it to break apart. Chemical weathering changes the molecular structure of rocks and soil. For instance, carbon dioxide from the air or soil sometimes combines with water in a process called carbonation. This produces a weak acid, called carbonic acid that can dissolve rock. Dissolution – This process occurs when water comes into contact with rocks and dissolves the minerals that make up that rock into individual elements. Hydrolysis – The breakdown of rock by acidic water to produce clay and soluble salts. When rocks sit in water for a very long time they begin to break down and have a clay like structure. Oxidation – The breakdown of rock by oxygen and water, often giving iron-rich rocks a rusty- colored weathered surface. Rocks undergone this process goes more fragile and brittle compared to other rocks. Carbonation – formed when water combines with carbon dioxide. Carbonic acid dissolves or breaks down minerals in the rock. Carbonation occurs on rocks which contain calcium carbonate such as limestone and chalk. C. Endogenic Processes A process occurring in Earth's interior that creates relief by elevating mountains and land masses, and depressing basins and ocean floors. The following are example of endogenic processes; tectonic movements, magmatism, metamorphism and seismic activity. Endogenic processes can be categorized as follows; Slow movement (Diastrophism) and sudden movement Diastrophism – It is the process of deformation of the Earth's crust which involves folding and faulting. Diastrophism is derived from the Greek ―diastrophḗ‖ which means distortion or dislocation. Diastrophism is even divided into 2; Epeirogenic – Land or continent forming movement. Process occurs through the help of solidifying magma which rose to the surface making a new layer of land. Orogenic – Mountain forming movement. Process takes place at a convergent plate margin when plate motion compresses the margin. On the other hand, sudden movement includes Volcanism and Earthquakes. Volcanism – is the eruption of molten rock (magma) onto the surface of a planet. A volcano is the vent through which magma and gases are discharged. Magmatism – is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks. It does so through magmatic activity or igneous activity, the production, intrusion and extrusion of magma or lava. Through this new ascending magmas produce additional mass and volume to the Earth's surface and subsurface. As various materials return into the molten state. Metamorphic rock subjected to stress may heat to the point where it turns into magma below the surface. This magma then begins the cycle again by creating igneous rock. Events in the cycle can happen in more than one order. Earthquake – An earthquake is the shaking and vibration of the Earth's crust due to movement of the Earth's plate tectonics. Intensity – describing the severity of an earthquake in terms of its effects on the earth's surface and on humans and their structures. Magnitude – magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded by seismographs.  Activities Identification ________1. It is formed from solidification of molten rock material. ________2. Composed of 2 or more minerals or substances. They are similar to minerals in that they must be solid and occur naturally. ________3. A naturally occurring and inorganic solid, with a definite chemical composition and a crystalline structure. ________4. A basic concept in geology that describes transitions through geologic time among the three main rock types ________5. Formed through the accumulation, compaction, and cementation Complete Venn diagram by providing at least 5 the similarities and differences of each Essay Based upon your understanding and previous learning about the topics, what could have been the underlying factor causing the changes on geologic structure through endogenic processes. (Discuss your answer in a minimum of 10 sentences) Short answer 1. What are the physical properties of minerals ? 2. How are rocks classified ? 3. Describe how the following rocks are formed. a. igneous rock b. sedimentary rock c. metamorphic rock CONCEPT MAPPING Complete the provided concept map