Earth Science PDF

EARTH AS A UNIQUE PLANET B. HYDROLOGIC SCIENCE AND ITS BRANCHES - Study of the earth’s bodies of water INTRODUCTION TO EARTH SCIENCE...

EARTH AS A UNIQUE PLANET B. HYDROLOGIC SCIENCE AND ITS BRANCHES - Study of the earth’s bodies of water INTRODUCTION TO EARTH SCIENCE - In its widest sense, hydrology encompasses the study of the occurrence, the movement, the physical, and Earth Science is a field of study concerned with the planet chemical characteristics of water in all its forms within Earth or one or more of its parts. It includes the sciences used to the earth’s hydrosphere. study the lithosphere (the solid portion of the earth), the atmosphere (the gaseous surrounding of the earth), the Engineering hydrology - concerned with the design of man- hydrosphere (the ice, water, and water vapor at or near the made structures that control the flow and use of water. earth’s surface), the biosphere (the zone at or near the Earth’s surface that supports life) and space beyond the atmosphere. Glaciology - the study of Glaciers and ice caps. Earth Science covers a range of subject matter. It includes geology, geophysics, meteorology, climatology, oceanography, hydrology, astronomy, and astrophysics. Groundwater Hydrology - focuses on subsurface water in the unsaturated zones. BRIEF HISTORY OF EARTH SCIENCE Hydraulics - concerned with the dynamics and mechanics of water in its liquid state. The origin of the Earth Sciences lies in the myths and legends of the distant past. The creation story which can be traced to a Babylonian epic of the 22nd century BC and which is told in the Hydrography - description and mapping of the bodies of first chapter of Genesis proved to be the most influential. The water of the earth’s surface including the oceans with a story is cast in the form of Earth history and thus was readily particular concern on navigation charts. accepted as an embodiment of scientific as well as of theological truth. Hydrology - the study of water on and within the ground. Earth scientist later made innumerable observations of natural Hydrometeorology - focuses on water in the lower boundary phenomena and interpreted them in an increasingly of the atmosphere. multidisciplinary manner. The Earth Sciences, however, were slow to develop largely because the progress of science was Hydrometry - involves measurement of the surface water, constrained by whatever society would tolerate or support at particularly precipitation and stream flows. any one time. Limnology - the study of the lakes and inland seas. THREE PRINCIPAL COMPONENT DISCIPLINES OF Soil water physics - study of subsurface water in the EARTH SCIENCE unsaturated zones. A. ATMOSPHERIC SCIENCE AND ITS BRANCHES Oceanography - the study of oceans and seas. Aeronomy - study of the atmospheric regions above the lower Physical oceanography - the study of properties of sea water stratosphere. It deals with the phenomena such as airglow, (waves, currents, tides) auroras, and photochemical processes. Chemical oceanography – study of composition of sea water Climatology - has something to do with the long term weather and the physical, chemical, and biological processes that conditions on a global scale. govern changes in composition of sea water in time and in space. Meteorology - primarily concerned with the short-term weather variations in the atmosphere. Submarine geology - deals with the geologic evolution and topography of the ocean basins. Importance Biological Oceanography or Marine Biology - focuses on the plant and animal life of the sea. ✓ Weather forecasting – accurate predictions of the future weather conditions Importance ✓ Weather modification – to modify the weather such as suppressing the hail and fog and weaken hurricanes) – Dry Ice, Salt, and Potassium Iodide are ✓ Development and management of water resources some of the compounds used in weather modification ✓ Concern for groundwater quantity and quality. (Cloud seeding). ✓ Prevent drought and other climatic patterns. C. GEOLOGIC SCIENCE AND ITS BRANCHES Characteristics of earth making it suitable for Disciplines concerned with the physical chemical supporting life makeup of the solid earth. Astrogeology - study of rock record on the moon, planets, and their satellites. Our sun is a stable and long-lasting star Stars that are more massive than the sun burn hotter and Economic geology - study of mineral commodities in which usually don’t live long enough for planets to develop life. Less modern civilization is heavily dependent. massive, younger stars are often unstable and are prone to blasting their planets with bursts of radiation. Engineering geology - concerned with the engineering properties of geologic materials, including their strength, compactability, and permeability and the influence of these properties on the selection of locations for buildings, roads, Water world and railroads, bridges, dams, and other major civil features. It is unique among planets in our solar system for having water in its liquid form at the surface, in an amount conducive to life Geochemistry - the study of chemistry of rocks. evolving. Not too much to cover the mountains, and not so little that it's a dry desert, as Mars and Venus. Geochronology - study of the isotonic chemistry and age dating rocks. Geomorphology - study of landforms which is concerned with We’re at just the right distance from the sun the description of the features of the present terrestrial surface Our planet receives enough energy to allow water to exist as and an analysis of the process that gave rise to them. a liquid on its surface. Too far, and the vital compound stays locked up as ice. Too close, and the water would rapidly Geophysics - study of physical properties of rocks at the evaporate into the atmosphere. earth’s surface and interior. Mineralogy - study of minerals We have an ozone layer in the atmosphere to block harmful Paleontology - study of fossils and fossil records. rays Ancient plantlike organisms in the oceans added oxygen to the Pedology - study of soil atmosphere and created a high-altitude layer of ozone that shielded species from lethal radiation. Petrology - study of rocks Seismology - study of earthquakes Gas-giant neighbors Structural geology - study of the structures in the solid earth. Jupiter. In general, gas giants tend to clump up near their home stars. But because they're toward the outside of our solar system, their intense gravity conveniently catches wayward Volcanology - study of volcanoes asteroids and comets. Importance Temperature Life seems to be limited to a temperature range of -15˚C to ✓ Exploration for accumulations of fossil fuels (coal, oil, 115˚C. In this range, liquid water can still exist under certain and natural gas, geothermal energy, and mineral conditions. Low temperature can cause the freezing of water, deposits) making liquid water unavailable while high temperatures cause ✓ Earthquake prediction and control the quick evaporation of water. ✓ Selection of locations for buildings, roads, railroads, bridges, dams, and other major civil features. Energy Layers of the atmosphere The Earth has a steady input of either light or chemical energy, cells can run the chemical reactions necessary for life. Too little Troposphere - is the layer of the atmosphere nearest to earth. sunlight or too few of the chemicals that provide energy to All weather conditions happen in the troposphere. cells, such as iron or sulfur, organisms die. Light energy becomes a problem if it makes a planet too hot. Stratosphere - Most jets fly in this layer. The protective ozone is at the top of the atmosphere (It protects us from the ultraviolet radiation of the sun.) Four earth subsystems Mesosphere The Earth consists of four subsystems, across whose boundaries matter and energy flow. These subsystems include the The mesosphere is the coldest layer of the lithosphere (the solid portion of the earth), the atmosphere atmosphere. (the gaseous surrounding of the earth), the hydrosphere (the ice, water, and water vapor at or near the earth’s surface), Meteors burn up in this layer. and the biosphere (the zone at or near the earth’s surface that Radio waves are reflected back to earth in the supports life). mesosphere. These subsystems of the Earth interact with each other and these four subsystems are independent and have their Thermosphere respective mandates or functions. Each can only succeed if all four subsystems are able to perform their respective functions. The thermosphere is the hottest layer of the The Earth system is essentially a closed system. It receives atmosphere. energy from the sun and returns some of this energy to space. Curtains of light called auroras occur in this layer. Exosphere LITHOSPHERE The exosphere is the outermost layer of the The lithosphere is the solid part of the earth that atmosphere. Satellites orbit earth in the exosphere. includes the rocks of the crust and mantle, the metallic liquid outer core, and the solid metallic inner core. Plate Tectonics plays an important role shaping the surface of the Earth. HYDROSPHERE The primary driving mechanism is the Earth's internal heat, such as that in mantle convection. A dynamic mass of liquid that is in constant motion, evaporating from the surface and bodies of water to the atmosphere, and will be back in the form of precipitation, running in land, bodies of water, and ATMOSPHERE oceans again. About 70% of the Earth is covered with liquid water The atmosphere is the thin gaseous layer that (hydrosphere) and much of it is in the form of ocean envelopes the planet. It is also where the weather and water. climate occurs. Only 3% of Earth's water is fresh: two-thirds are in It is composed of gas layers that serves as protection the form of ice, and the remaining one-third is present from ultraviolet radiation and extraterrestrial objects in streams, lakes, and groundwater. like asteroids. The present atmosphere is composed of 78% Nitrogen (N), 21% Oxygen (O2), 0.9% Argon (Ar), and trace amount of other gases. The 5 major earth oceans One of the most important processes by which the heat on the Earth's surface is redistributed is through ✓ ARCTIC OCEAN atmospheric circulation. ✓ SOUTHERN OCEAN There is also a constant exchange of heat and ✓ INDIAN OCEAN moisture between the atmosphere and the ✓ ATLANTIC OCEAN hydrosphere through the hydrologic cycle. ✓ PACIFIC OCEAN BIOSPHERE Types of luster The biosphere is the set of all life forms on Earth. Metallic - Minerals reflect light like metals. Metallic It covers all ecosystems—from the soil to the luster often tarnishes to a dull luster. (Example: rainforest, from mangroves to coral reefs, and from Galena the plankton-rich ocean surface to the deep sea. Vitreous - The mineral reflects light like glass. For most of the life on Earth, the base of the food Sometimes glassy luster is used instead of vitreous. chain comprises photosynthetic organisms. During (Example: Fluorite) photosynthesis, CO2 is sequestered from the Pearly - The luster of a pearl or mother of pearl. atmosphere, while oxygen is released as a by- (Example is Biotite Mica) product. The biosphere is a CO2 sink, and therefore, Silky - The luster of silk. It occurs in minerals with a an important part of the carbon cycle. fibrous structure. (Example: Satin Spar) Adamantine - The luster of a diamond ROCKS AND MINERALS MINERALS Dull/earthy - The mineral does not reflect light and has the same appearance as soil. (Example: Limonite) In Chemistry, mineral is any naturally occurring chemical element or compound, but in mineralogy and geology, minerals are chemical elements or compound that have been formed through inorganic processes. HARDNESS is the measure of the resistance of a mineral to abrasion. Mohs scale is used to determine the hardness of a mineral. To say that something is a mineral, it must have all the following characteristics: Mohs Hardness Scale is designed by German geologist/mineralogist, Friedrich Mohs in 1812. The test simply 1. It is naturally occurring (not man-made or machine compares the resistance of a mineral relative to the 10 generated) reference minerals with known hardness. 2. It is inorganic (not a byproduct of living things 3. It has a definite arrangement of atoms, that is solid 10 Reference Minerals in the Mohs Scale with an orderly crystalline structure 4. Its chemical composition can be expressed in terms of chemical formula. 1 – Talc 6 –Orthoclase Feldspar Water is not a mineral because it is not solid in structure. 2 – Gypsum 7 – Quartz Despite the fact that pearl is naturally occurring, crystalline solid, and its composition can be expressed in a chemical 3 – Calcite 8 – Topaz formula, still it is not a mineral because it is organic, a byproduct of clams. Ice tube and iron nail are both man-made 4 – Fluorite 9 – Corundum so they’re not considered as a mineral while graphite, snowflakes, salt, Gold, and Silver meets all the requirements to 5 - Apatite 10- Diamond be called a mineral. COLOR Properties of minerals the color of a fresh surface mineral is a clue to their identification. A lot of minerals can exhibit same or similar colors. Individual minerals can also display a variety of colors resulting from impurities and from some geologic processes like LUSTER weathering. It is the quality and intensity of reflected light exhibited by the mineral. Can also be described as the general appearance of the surface in reflected light STREAK Mineral groups is the mineral’s color in powdered form. Silicates - minerals containing 2 of the most abundant obtained by rubbing a mineral on a white unglazed elements in the Earth’s crust, namely, silicon and tile or porcelain plate oxygen. Examples of streak: pyrite exhibits gold color but has Oxides - minerals containing Oxygen anion (O2) a black or dark gray streak. combined with one or more metal ions Sulfates - minerals containing Sulfur and Oxygen anion (SO4) combined with other ion Sulfides - minerals containing sulfur anion (S2) CRYSTAL FORM combined with one or more ions. Some sulfides are sources of economically important metals such as copper, lead and zinc. The form reflects the supposedly internal structure of the mineral. It is the natural shape of the mineral before the Carbonates - minerals containing the carbonate anion development of any cleavage or fracture. (CO3) combined with other elements Native Elements - minerals that form as individual elements. Metals and Inter-metals minerals with high thermal and electrical conductivity, typically with metallic CLEAVAGE AND FRACTURE luster, low hardness (gold, lead) Semi-metals - minerals that are more fragile than Cleavage is the property of some minerals to break metals and have lower conductivity (arsenic, bismuth) along specific planes of weakness to form smooth, flat Nonmetals - nonconductive (sulfur, diamond) surfaces Halides - minerals containing halogen elements These planes exist because the bonding of atoms combined with one or more elements making up the mineral happens to be weak in those areas. Some minerals do not break along cleavage planes but instead it is described as fracture, which is irregular or without any definite pattern or direction. ROCKS are naturally formed, non-living mass of organic and inorganic earth material consisting of one or more minerals that are held SPECIFIC GRAVITY together in a firm, solid mass. is the weight of the mineral compared to the weight of an Rocks are classified by how they are formed, their equal volume of water. Native metals are the heaviest ones. composition, and texture Rocks change over time through the rock cycle OTHER PROPERTIES Types of rocks Other properties of minerals include magnetism, odor, taste, reaction to acid, fluorescence. IGNEOUS ROCKS Examples: are rocks that form from the cooling of hot molten masses called magma (hot molten mass that can be found beneath the ✓ Magnetite is strongly magnetic earth's surface) or lava (hot molten mass on the earth's surface). ✓ Sulfur has distinctive smell ✓ Halite is salty ✓ Fluorite has the ability to disperse ultraviolet rays to visible light ✓ Calcite fizzes with acid as with dolomite but in Magma can form powdered form. ✓ When rock is heated ✓ When pressure is released ✓ When rock changes composition ✓ Magma freezes between 700 °C and 1,250 °C ✓ Magma is a mixture of many minerals Two types of igneous rocks METAMORPHIC ROCKS Intrusive igneous rocks - Formed beneath the earth's surface. are formed when igneous or sedimentary rocks are subjected to heat and pressure. Extrusive igneous rocks - Formed on the earth's surface. Examples of metamorphic rocks Igneous Rocks can also be classified as: Quartzite a coarse-grained metamorphic rock Felsic: light colored rocks that are rich in elements such as derived from sandstone. aluminum, potassium, silicon, and sodium Marble a metamorphic rock that comes from metamorphosed limestone or dolomite. Mafic: dark colored rocks that are rich in calcium, iron, and Slate formed when shale is subjected to heating magnesium, poor in silicon magma. Gneiss formed when conglomerate is exposed to heat and pressure Igneous Rocks can also be classified as: Coarse-grained: takes longer to cool, giving mineral crystals ROCKS, MINERALS AND SOCIETY more time to grow Earth's crust is the source of a wide variety of minerals, many Fine-grained: cools quickly with little to no crystals of which are useful and essential to people. As a matter of fact, all manufactured product contains materials obtained from minerals. SEDIMENTARY ROCKS Most people are familiar with the common uses of basic metals, including Aluminum in beverage can, Copper in electrical wires, Gold in jewelry, and Silicon in computer chips. But fewer are are formed by the compaction and cementing together of aware that pencil Lead does not contain Lead metal but is sediments (materials that settle out of air and water), broken really made of the soft black mineral called graphite. pieces of rock-like gravel, sand, silt, or clay. The economic uses of rocks and minerals are important to us. No heat and pressure involve Consequently, a basic knowledge of the earth materials is essential to the understanding of all Earth science phenomena. Strata layers of rock Stratification-the process in which sedimentary rocks are arranged in layers Uses of some minerals Feldspar used to make porcelain, enamel, and as a building stone. Two types of sedimentary rocks Mica used for insulation in electrical equipment, wallpaper, and fireproof materials Clastic sedimentary rocks - Formed from broken bits and Talc used to make powder for cosmetic products pieces of other existing rocks that settle out of water or air. Ex. Calcite used in manufacturing cement and mortar and Conglomerate, sandstone for writing on the board Sulfur used in manufacturing sulfuric acid, explosives, Non-clastic sedimentary rocks dyes, insecticide, and soap Salt used as a preservative and additive Chemical - Formed from the materials that precipitated from Borax used in manufacturing soap, enamels, glass, water. Ex: Gypsum, halite or salt. washing powder, and welding Apatite used for fertilizer graphite-used as pencil Biological or organic - Formed from organic sediments that lead are remains of living organisms such as plants and shells. Ex. Iron used in industry and infrastructure projects Limestone, coal  Aluminum used for roofing and in making planes, Three types of Surface Mining cars and other transport vehicles Mercury used in thermometers, barometers, and industries Titanium used in paint pigments and bulletproof since OPEN-PIT MINING it was light but very strong Gold used for coins, jewelry, and in coating other Open-pit mining, also known as open-cast or open ornamental objects. cut mining, is a surface mining technique of extracting Silver used as conductor, making silverwares, coins, rock or minerals from the earth by their removal from and jewelry an open-air pit, sometimes known as a borrow. Copper used in electrical wirings Diamond used in industry and in making jewelry This is the most common type of surface mining. Open Quartz used in making optical instruments, radio and pit means a big hole (or pit) in the ground. The pit in electronic equipment because of its electrical mine is created by blasting with explosives and properties and in porcelain paints when in powdered drilling. It is used to mine gravel and sand and even form rock. STRIP MINING ORE MINERALS This mining type involves the removal of a thin strip of How they are Found, Mined and Processed for Human Use overburden (earth or soil) above a desired deposit, dumping the removed overburden behind the deposit, INTRODUCTION TO MINING extracting the desired deposit, creating a second, parallel strip in the same manner, and depositing the waste materials from that second (new) strip onto the is the process of mineral extraction from a rock seam first strip. This mining method is used for coal, or ore –a natural rock or sediment containing one or phosphates, clays, and tar mining. more valuable minerals. The minerals can range from precious "Strip mining" is the practice of mining a seam of Modern mining technology uses geophysical mineral, by first removing a long strip of overlying soil techniques that involve measuring the magnetic, and rock (the overburden); this activity is also gravity and sonic responses of rocks above and referred to as "overburden removal". around a prospective mineral ore body. It is most commonly used to mine coal and lignite is required to obtain any material that cannot be (brown coal). Strip mining is only practical when the grown through agricultural processes, or feasibly ore body to be excavated is relatively near the created artificially in a laboratory or factory. surface. in a wider sense includes extraction of any non- renewable resource such as petroleum, natural gas, or even water. Mining of stones and metal has been a human activity DREDGING since pre-historic times. Modern mining processes involve prospecting for ore bodies, analysis of the This is the process of mining materials from the bottom profit potential of a proposed mine, extraction of the of a body of water, including rivers, lakes, and desired materials, and final reclamation of the land oceans. after the mine is closed. Dredging is the removal of sediments and debris from the bottom of lakes, rivers, harbors, and other water SURFACE MINING bodies. It is a routine necessity in waterways around the world because sedimentation—the natural process is used to extract ore minerals near the surface of the earth. of sand and silt washing downstream—gradually fills The soil and rocks that covered the ores are removed through channels and harbors. blasting. Blasting is a controlled use of explosives and gas exposure to break rocks. UNDERGROUND MINING Types of fossil fuels is used to extract the rocks, minerals and other precious stones that can be found beneath the earth’s surface. In underground mining, miners need to create a tunnel so they can reach the COAL ore minerals. This kind of mining is more expensive and dangerous as compared to surface mining because miners - It is an important and primary fossil fuel present on need to use explosive devices to remove the minerals from the Earth. Coal resources are found predominantly where rocks that cover them. forest trees, plants and marshes existed before being buried and compressed millions of years ago. - Philippines uses approximately 50% coal resource to produce energy and electricity. Steps in Mineral Processing Sampling is the removal of a portion which represents a whole needed for the analysis of this material. There are four major ranks of coal. Analysis is important to evaluate the valuable component in an ore. This includes chemical, mineral 1. Anthracite is the highest rank of coal. It is a hard, and particle size analysis. brittle, and black lustrous coal, often referred to as Comminution is the process where the valuable hard coal, containing a high percentage of fixed components of the ore are separated through crushing carbon and a low percentage of volatile matter. and grinding. This process begins by crushing the ores 2. Bituminous Coal it usually has a high heating value to a particular size and finishes it by grinding the ores and is the most common type of coal used in electricity into a powder form. generation. It appears shiny and smooth at first Concentration involves the separation of the valuable glance, but when you look closely, you will see that it minerals from the raw materials. has layers. Dewatering uses the concentration to convert it to 3. Subbituminous Coal is black in color and dull, and has usable minerals. This involves filtration and a higher heating value than lignite. sedimentation of the suspension and drying of the 4. Lignite is also known as brown coal. It is the lowest solid materials harvested from this suspension. grade coal with the least concentration of carbon. OIL FORMATION OF FOSSIL FUELS - Most of the oil that we are using today started INTRODUCTION TO FOSSIL FUEL forming millions of years ago. Oil is an organic material, mostly algae, which was buried in mud at are basically remains of plants and animals that died the bottom of the sea and lakes. millions of years ago. They are the world’s primary - It is used mainly to produce transportation fuels and energy source that provide most of the energy petroleum-based products. Philippines imports crude support in transportation, electricity, and industries. oil and petroleum from Saudi Arabia and Russia. Most of the market are Petron Corporation, Pilipinas Shell, They are natural and finite resources that are very and Chevron Philippines. abundant and has a cheaper cost production - Petroleum products supply about 37 percent of U.S. compared to other resources present on Earth. They energy needs, with the transportation sector are considered as non-renewable energy source as consuming the most. they take millions of years to form. Coal, crude oil, and natural gas are all considered fossil fuels because they were formed from the NATURAL GAS fossilized, buried remains of plants and animals that lived millions of years ago. Because of their origins, fossil fuels have a high carbon content. - It is a naturally occurring hydrocarbon gas with the mixture of methane. It is the Earth’s cleanest fossil fuel and is odorless and colorless in its natural state. - Natural gas is produced from sedimentary rock formation by forcing chemicals, water, and sand down a well under high pressure. The Philippines’ main domestic source of energy is the Malampaya natural gas field which is located at Palawan Island. FORMATION OF FOSSIL FUELS EMISSIONS - Millions of years ago the remains of prehistoric plants - Fossil fuels emit harmful air pollutants long before and animals are buried beneath the Earth’s surface. they’re burned. Indeed, some 12.6 million Americans These remains were covered by mud. The mud are exposed daily to toxic air pollution from active oil sediment was buried by more sediments and It started and gas wells and from transport and processing to change into rock as the temperature and pressure facilities. These include benzene (linked to childhood increase. leukemia and blood disorders) and formaldehyde (a - In that case fossil fuels are formed in a low oxygen cancer-causing chemical). environment. The plant and animal remain were - A booming fracking industry will bring that pollution altered chemically by this process, and slowly to more backyards, despite mounting evidence of the changed into crude oil and natural gas. practice’s serious health impacts. Mining operations - Through the spaces of permeable rock, the oils move are no better, especially for the miners themselves, upwards and will be trapped if it reached generating toxic airborne particulate matter. impermeable rock. Oil companies can drill down through the impermeable rocks to get it out. Strip mining—particularly in places such as Canada’s boreal - They are then able to turn it into products we can use, forest—can release giant carbon stores held naturally in the such as petrol and diesel. On the other hand, coal can wild. be extracted from the Earth through underground mining. Once it has been extracted, it can be used to fuel power plants for electricity. GLOBAL WARMING - When we burn oil, coal, and gas, we don’t just meet DISADVANTAGES OF FOSSIL FUELS our energy needs—we drive the current global warming crisis as well. Fossil fuels produce large LAND DEGRADATION quantities of carbon dioxide when burned. - Carbon emissions trap heat in the atmosphere and - Unearthing, processing, and moving underground oil, lead to climate change. In the United States, the gas, and coal deposits take an enormous toll on our burning of fossil fuels, particularly for the power and landscapes and ecosystems. The fossil fuel industry transportation sectors, accounts for about three- leases vast stretches of land for infrastructure such as quarters of our carbon emissions. wells, pipelines, access roads, as well as facilities for processing, waste storage, and waste disposal. - In the case of strip mining, entire swaths of terrain— including forests and whole mountaintops—are scraped and blasted away to expose underground EARTH’S WATER RESOURCES coal or oil. Even after operations cease, the nutrient- leached land will never return to what it once was. Water is the most critical nutrient necessary for sustaining life. - As a result, critical wildlife habitat—land crucial for If there is no water on earth, life would not exist and we would breeding and migration—ends up fragmented and not have the kind of biodiversity that we have now. destroyed. Even animals able to leave can end up suffering, as they’re often forced into less-than-ideal habitat and must compete with existing wildlife for resources. DISTRIBUTION OF EARTH’S WATER The water resources of the Earth are made up of 97% salt WATER POLLUTION water and 3% freshwater (Figure 1). This freshwater exists in the solid-state as ice, polar ice caps, and glaciers and liquid form in freshwater ecosystems and groundwater. Freshwater Coal, oil, and gas development pose myriad threats to our ecosystems and groundwater serve as storage locations for waterways and groundwater. Coal mining operations wash water and are known as reservoirs. acid runoff into streams, rivers, and lakes and dump vast quantities of unwanted rock and soil into streams. Oil spills and leaks during extraction or transport can pollute drinking water These reservoirs comprise 3% of the fresh water available on sources and jeopardize entire freshwater or ocean ecosystems. earth and include oceans, glaciers, groundwater, lakes, rivers, and the atmosphere. Water molecules present in reservoirs may pass through it very fast or may remain for a longer time. Types of Freshwater bodies Transpiration is a process wherein plants absorb water from the soil and release excess water vapor to ✓ Streams the atmosphere through the pores of their leaves. ✓ Wetlands Precipitation is a process wherein liquid or solid ✓ Lakes water molecules released from the clouds fall to the ✓ Rivers ground. When liquid water reaches the ground, it ✓ Hotsprings goes to rivers that stream down to oceans and lakes. On the other hand, water molecules that cascade as snow stay longer on top of the mountains. This snow may stay as part of the ice in glaciers for hundreds or thousands of years. EARTH’S WATER RESOURCES Runoff plays an important part in the water cycle wherein rainwater, melted snow and ice flow down Water has unique properties that allow it to move through rivers and lakes. At the surface, the water may almost anywhere on Earth. The water molecule found in your eventually evaporate and go back to the atmosphere. glass of water today could have been buried with a fossil million years ago. In the prevailing billions of years, the molecule possibly stayed solid in a glacier or liquid below the ground. The molecule surely was high up in the atmosphere and maybe inside the stomach of a dinosaur. Where will that water SOURCES OF WATER POLLUTION molecule go next? AGRICULTURE - Farm fields use big amount of chemicals such as THE HYDROLOGIC CYCLE fertilizers on a regular basis. The chemicals dissolve in rainwater. Runoff may carry some of the chemicals to Earth’s water exists in all three states and may be present in nearby rivers or lakes. Dissolved chemicals causes an various environments. As it transforms from one state to excessive amount of growth of water plants and another, it must enter different processes. The process by which algae. water moves around on Earth’s surface is known as the - This may result in dead zones within the water hydrologic (water) cycle and is powered by the solar energy wherever nothing can live. Also, some of the chemicals that comes from the sun. The water cycle consists of different may seep in the ground and contaminate processes. groundwater. They may end up in water wells. - If people consumed contaminated water, they may get serious health problems. Waste (fecal matter) from farm animals also can contaminate water. The waste contains microorganisms that cause sickness. Processes in the water cycle Evaporation is a process of turning liquid into its gaseous state. The gaseous state produced in this process is called water vapor. The water vapor evaporates from the surface water from oceans or INDUSTRY freshwater ecosystems but only water molecules go to the atmosphere, the salt and other minerals stay in the reservoir. The energy from the sun causes this - Many industries produce waste products that are toxic evaporation. such as lead, arsenic, and mercury. Aside from these toxic chemicals, nuclear powerplants produce radioactive wastes that are cancerous and pose Condensation is a process of turning gaseous serious health problems. molecule to liquid phase. The gaseous water molecule - Also, human activities may spill oil in the ocean and stays in the atmosphere until it undergoes other bodies of water which can seep into the condensation to become tiny droplets of liquid. The groundwater making it unsafe for human consumption. droplets of liquids in clouds, which are blown about the globe by the wind collide and grow, and fall from the sky as precipitation in the form of rain, hail, snow, etc. MUNICIPAL AND COMMUNITY SOURCES Examples and sources of solid wastes - Households and businesses in a community may also ✓ Disposal of excess food causes the generation of food pollute the water supply. Activities such as the refuse. Surprisingly, it constitutes a large percentage application of fertilizers and chemicals to lawns and of solid wastes even if there is a global problem of farms cause water pollution. hunger. - The chemicals and fertilizers dissolve in rainwater and ✓ Paper wastes come from businesses and homes as end up in nearby rivers or lakes. Also, underground well. As a person uses more paper, more wastes are septic tanks develop leaks that may contaminate generated. groundwater. ✓ A newspaper can be useful for a day but is usually - Besides, treated wastewater dumped by municipal disposed of when out of date. sewage treatment plants pollutes rivers or lakes ✓ When a person consumes pre-packaged products, because they are not be treated enough and still solid wastes are generated. The excess packaging of contain bacteria or hazardous chemicals. products, such as food, electronics, and furniture, contributes to the great amount of paper and plastic wastes. Even though water resources become polluted due to human ✓ Constructions of different structures also contribute to activities, we need water for life itself and therefore, must other types of solid wastes such as wood, cement, protect it more than any other resource found on Earth. So how rubbers, metals, and ashes. can we prevent water pollution? Here are some tips which you can do to lessen water pollution LIQUID WASTES 1. Proper waste disposal - do not pour oil or household usually come in the forms of wastewater, fats, oil and grease, chemicals on the drain. Avoid spilling them on soil household fluids, and mechanical oil. They are regularly because it can seep to the ground and might generated because of constant human activities. More contaminate the water. wastewater is generated as people use excessive water in 2. Lesser use of garden chemicals - use compost or activities such as household and industrial cleaning, watering of organic fertilizers for your garden needs. If it is plants, and feeding animals. possible, grow plants that require lesser chemicals or fertilizer to grow. 3. Avoid pet and farm animal wastes to enter water supply - the wastes may contain disease-causing bacteria. Examples and sources of liquid wastes ✓ Cooking using oils and lard contributes to liquid waste WASTES GENERATION AND EFFECTS production. ✓ Bleaches, liquid detergents, and insecticides that are William Rathje disposed of in drains are also liquid wastes. ✓ Disposed mechanical oils from car repair shops and car manufacturing sites also contribute to liquid Source reduction is, on the face of it, perhaps the most wastes. appealing of all the possible approaches to solid-waste management. GASEOUS WASTES Three types of waste Carbon oxides, nitrogen oxides, methane, sulfur oxides, and aerosols are the most common type of gaseous wastes. They are usually produced through the combustion of different materials. Many of the materials we use are produced in SOLID WASTES facilities that emit these gaseous wastes. - are considered as the most common and most abundant type of wastes. - These may be in the form of food leftover, paper, plastics, wood, ashes, rubber, and metals. These are generated from different human activities. Examples and sources of gaseous wastes EFFECTS OF LIQUID WASTES TO ENVIRONMENT ✓ A person’s use of materials such as plastics and metals - Liquid wastes from solid wastes and chemicals indirectly contributes to the increase of gaseous produce leachate that seeps through the soil and wastes in the atmosphere. water. It causes soil sterilization and water pollution. ✓ Improper garbage disposal of households, industries, - Run-offs from farms that reach coasts, rivers, and and commercial institutions promotes methane lakes cause eutrophication. Eutrophication happens production. when excess nutrients such as nitrates and phosphorus ✓ The use of hairsprays and aerosols at home adds to go into water resources. These compounds cause algal the gaseous wastes in the atmosphere. blooms that overcrowd the water surface. ✓ Garbage incineration produces harmful carbon - Chemical wastes and eutrophication due to run-offs oxides. both cause fish kills and death of other organisms. ✓ Automobile usage is one of the major sources of carbon monoxide wastes. ✓ Using electricity has a part in generating gaseous wastes due to the fossil fuels used in the production of EFFECTS OF GASEOUS WASTES TO ENVIRONMENT energy. - Gas exhausts from automobiles and factories cause acid rain when these wastes combine with the rain. Acid rain destroys plants, buildings, and livelihoods. EFFECTS OF WASTES TO HEALTH AND ENVIRONMENT They also contaminate the soil and water resources. - Methane from decomposing solid wastes contributes - The increase in the population of the world causes an to greenhouse gases. increase in the number of wastes generated. Large - Chlorofluorocarbons from gaseous wastes cause the amounts of wastes need to be properly disposed of depletion of the ozone layer. The ozone layer is every day. If these wastes are not properly managed important because it protects us from the harmful rays and disposed of, they will have negative effects not of the sun. only on the environment but also on the health of the people. - Solid waste is the most abundant type of waste. It EFFECTS OF SOLID WASTES TO HEALTH may be in the form of food refuse, paper, plastics, wood, ashes, rubber, and metals. Liquid waste usually - Solid wastes contaminate water resources. The comes in the form of wastewater. Fats, oil and grease, contaminated water may cause gastrointestinal household fluids, and mechanical oil are some of its diseases. examples. Finally, gaseous waste is usually produced - People residing near landfills experience skin from the combustion of different materials. The most diseases due to continuous contact with wastes. common examples include carbon monoxide, nitrogen - Solid wastes, especially biodegradable ones, attract oxides, methane, sulfur oxides, and aerosols. rodents and flies that bring various diseases to people. EFFECTS OF SOLID WASTES TO ENVIRONMENT EFFECTS OF LIQUID WASTES TO HEALTH - Solid wastes end up in waterways that pollute water resources. - Liquid wastes such as mercury from mines and - Floods are caused by improperly disposed wastes hospitals cause poisoning in humans when they that block the drainages. consume mercury-contaminated fishes. - Some non-biodegradable wastes can reach the - Shellfish contamination due to algal blooms may oceans. Marine animals sometimes see them as food cause poisoning in humans when consumed. and ingest these wastes. Sometimes, these wastes - 3Strong chemicals that make up some liquid wastes affect the growth of marine animals. distress the reproductive systems of humans, especially those of males. - Water poisoning also threatens humans because of liquid wastes in water resources. EFFECTS OF GASEOUS WASTES TO HEALTH Disintegration is a process that describes how large masses of rocks and mechanically broken down into - Gaseous wastes in the atmosphere are one of the smaller chunks or fragments. primary causes of respiratory diseases in humans. Decomposition is a process that describes changes in - Some of these wastes increase cancer risks and lung the chemical composition of rocks to form new weakening. products. - Carbon monoxide, generated from exhausts, can cause neurological dysfunctions and even death. The weathered rocks and other products of weathering such as clasts (broken fragments of rocks) are transported elsewhere in a process called erosion. Simple waste management practices There are several types of weathering under two major categories, the mechanical weathering and chemical ✓ Avoid plastics weathering. Biological weathering, a type of weathering that ✓ Buy food that has minimal packaging is caused by living organisms, can fall to both mechanical and ✓ Compost your kitchen wastes chemical weathering. ✓ Perform transactions electronically to reduce the use of paper ✓ Consider making soaps and detergents at home ✓ Repurpose other sturdy containers MECHANICAL WEATHERING ✓ Donate items whenever possible ✓ Reduce, reuse and recycle also called physical weathering and disaggregation, is weathering that Involves the disintegration of rocks causing it to break while retaining its chemical properties. WEATHERING Types of Mechanical Weathering Physical Change refers to changes limited in the physical attributes or appearance of an object without changing its Unloading - The type of mechanical weathering chemical composition These includes changes in an objects' caused by the expansion of the upper portion of a color, shape and texture. An example of this is cutting a paper. block intrusive igneous rock. The expansion was Cutting the paper changes its shape and size but does not caused by the differential pressure from the bottom affect the chemical composition of paper, thus this is considered of the block and the exposed strata. It is common for as physical change. granitic rocks and rocks that lack internal bedding. Thermal Expansion and Contraction - High Chemical change is the type of change that is not only limited temperature causes rock to expand while low to its physical properties. This type of change involves changes temperature causes rocks to contract (just like the in its chemical composition and the formation of new products. direct proportionality between temperature and Common examples of chemical change include change in volume in Charles' Law). The variation between temperature, change in color, noticeable odor, formation of temperatures can cause rocks to crack. This type of precipitate, effervescence etc. weathering is common for places that experience extreme swings in daily temperatures. Earth's landforms and terrains are constantly being carved by Freeze-Thaw Weathering - Also called ice wedging, natural geologic processes. No rock, no matter how hard it is, is this is a type of mechanical weathering that happens prone to change and degradation. Examples of these geologic when water penetrates rock cracks. As temperature processes that helped shape the Earth's surface are weathering drops, the water freezes and expands causing the and erosion. These two processes always go side-by-side with widening of cracks. Continuous freezing and thawing one another. will cause the crevices to expand larger which will further lead to breaking the rock. Salt crystal growth - This type of weathering is quite similar to freeze- thaw. In this type of weathering, National Geographic water that contains dissolved salt penetrates cracks and crevices. As temperature rise, water will weathering is a process wherein rocks and minerals are broken evaporate leaving the salt inside it. The crystal salt down and dissolved on the Earth's surface. This is aided by inside the crevices will exert pressure and will cause natural forces called agents of weathering such as water, ice, the larger wedges. This commonly happens in place acids, salts, plants, animals and even changes in the experiencing high temperature and evaporation rate temperature. and even in rocks near seawater.  Hydration - In weathering by hydration, water VARIABILITY IN WEATHERING molecules will attach to crystalline structure of minerals. Water can join the host through hydration In this part of the module, the factors affecting the rate, extent causing the mineral to expand and leave through and type of weathering will be discussed. dehydration causing the mineral to shrink. Did you know that? CHEMICAL WEATHERING Bowen's Reaction Series is a tool used to describe the In contrast with mechanical, chemical weathering is a type of crystallization sequence of common igneous silicate minerals weathering caused by changes in chemical properties of shows the crystallization temperature for each mineral. minerals and rocks. Changes in the chemical composition of Minerals at top have the highest crystallization temperature rocks and minerals may also help break down rocks. which -means that they will crystallize first from a cooling magma. Itis the work of a petrologist named Norman L Bowen. The products of chemical weathering are commonly stable at the Earth's surface (just like metamorphic rocks, rocks formed Climate areas that are cold and dry tend to have through extreme heat and pressure). Chemical weathering is slow rates of chemical weathering and weathering is most catalyzed by agents such as water, carbon dioxide and mostly physical, chemical weathering is most active in oxygen. areas with high temperature and rainfall. Rock Type Rock susceptibility on weathering is also dependent on the rock type. Some rocks contain minerals that are highly susceptible to weathering Three Chemical Weathering Processes while there are rocks that contain minerals that are highly resistant to weathering. In the Bowen's reaction Oxidation - A process where oxygen (from water) series, minerals that crystallize first are susceptible bonds with other elements from rock forming minerals and minerals crystallize last are more resistant more forming other substances that are more stable, lower that. malleability, larger volume and more distinct color. It Rock Structure rate of weathering is affected by the commonly occurs to metals present in rocks such as presence of joints, folds, faults, bedding planes aluminum and iron. Oxygen bonds with these metals through which agents of weathering enter a rock mass. forming aluminum and iron oxides. Highly jointed/ fractured rocks disintegrate faster Solution and Carbonation - Solution is the chemical than a solid mass of rock of the same dimension process of dissolving rock-forming minerals in water. Topography Physical weathering occurs more quickly In this reaction, mineral- forming ions are dissociated to highly elevated areas with steep slope due to the and are carried away in the water. Some rocks help of gravity. In areas with gentle slopes, water containing mineral that are insoluble or slightly may stay longer on the surface which causes chemical insoluble undergoes solution process when water is weathering to occur more quickly acidic. Lichens and mosses aid in the solution process Time The length of exposure to agents of weathering of such types of rocks by secreting acidic substances affects the rate of erosion. Parts of rock boulders that that readily mix with water from precipitation. are exposed are more susceptible to weathering Carbonation is the chemical weathering process that because of its exposure to water, air and other decomposes rocks through the aid of water and agents of weathering Also, some rocks submerged in carbon dioxide. This process is common to rocks water (both freshwater and seawater) or are containing carbonates (CO) such as limestone. commonly in contact with water are more prone to Hydrolysis - In this process, water molecules alone, weathering processes such as hydration and rather than oxygen and carbon dioxide in it, react hydrolysis. with the components of rock-forming minerals. This is commonly aided by the dissociation of the hydronium ion (H) and hydroxyl (OH) binding with other elements and compounds in rocks. This process is different from DIFFERENTIAL WEATHERING AND EROSION the process of hydration. In hydration, water moves in and out of the mineral causing the rock to shrink, swell If a landscape contains a variety of rocks, some rocks are more and break without changing its chemical properties. In - susceptible to weathering and some are more resistant. In this hydrolysis, ions from water combine with other case, more susceptible rocks undergo weathering faster and elements/compounds forming new products. rock fragments are transported through the process of erosion. This variability in the rate of weathering in rocks in a landform is called differential weathering.  The effect of differential weathering is highly visible to some Rocks that are subjected to forces may deform in two ways. landforms. Highly resistant rocks tend to -withstand weathering leading to the formation of high-rise landforms such as cliffs FRACTURE (BREAK) that happens in the uppermost part of the and mountains. Susceptible rocks are easily eroded and crust which tends to break when subjected to compressional or transported leading to the formation of gentler slopes, valleys tensional forces. and even subdued hills. Two types of fractures DEFORMATION OF EARTH'S CRUST: FOLDING AND faults that breaks along when there is considerable FAULTING movement joints are those breaks where there is little or no INTROUCTION TO DEFORMATION movement. Deformation refers to the changes in volume and or shape of FOLD (BEND) happens deep within the crust and the rocks do rocks as they are squeezed by compressional forces or not break the way they do at the earth's surface. stretched by the tensional forces. Rocks bend and go out of shape. Stress is the force per unit area applied on the rock Hanging wall is a block of rocks resting on the fault Strain is the change in shape or volume of the rock that plane. experienced stress. Footwall is a block below the fault plane. Types of stress and resulting strain Types of faults Tensional stress involves forces pulling in opposite DIP-SLIP FAULTING involves the movement of blocks of rocks directions, which results in strain that stretches into thin mainly in vertical direction, move up and down. rocks. Compressional stress involves forces pushing A. Normal fault formed when the crust is stretched or pulled together or the stress that results from the shortening apart by forces in opposing directions and when the hanging in one dimension of an elastic body due to oppositely wall moves down with respect to the footwall directed collinear forces tends to crush it. Shear stress involves transverse forces that result in B. Reverse fault when the crust is squeezed or compressed, the deformation of material by slippage along a plane hanging moves up relative to the footwall of planes parallel to the imposed stress or regions of material moving past each other. STRIKE-SLIP FAULTING involves movement chiefly in the horizontal direction (sideways or laterally) Stress and strain A. Right-Lateral Strike-Slip Fault sideways movement of fault The resulting strain in rocks can be classified into elastic, ductile to the right. Example: San Andreas Fault in California U.S.A. or brittle depending on the stress applied in the material. B. Left-Lateral Strike-Slip Fault if the other block moved to your left, then the fault is a left- lateral strike-slip fault. Elastic deformation is strain that is reversible after a Example: Philippine Fault stress is released. Ductile deformation occurs when enough stress is applied to the material that causes changes in shape and no longer be able to return to its original shape. Philippine Fault is an example of Strike-Slip Fault. In reality, Yield point is the point at which elastic deformation is the Philippine Fault consists of several faults parallel to one surpassed and strain becomes permanent. another and it is called Philippine Fault Zone. The fault extends Brittle deformation materials respond to stress by from Luzon through the eastern part of the Visayas, down to breaking and fracturing. eastern Mindanao  ENDOGENIC PROCESSES METAMORPHISM PLATE TECTONICS You have learned from the previous lesson that rocks/minerals In 1912, geophysicist and a German meteorologist Alfred become unstable and change into another mineral as a Wegener (1880-1930) developed the Continental Drift Theory response to heat, pressure and chemically active fluids. This that explains how continents shift position on Earth's surface. process is known as metamorphism through which pre-exiting Continental drift is the gradual movement of the continents over rocks transformed into metamorphic rocks. time. The upper layer of the crust is broken down plates, which sit on a molten rock. The movement of this lower molten layer, Factors controlling the mineral assemblage of metamorphic rocks. called plate tectonics, causes the plates to shift. ◆ Bulk composition of the original rock Wegener theorized that all the continents were once interconnected from a supergiant land mass, which he called ◆ Attained pressure/temperature during metamorphism Pangaea. ◆ Composition of fluid phase that was present during According to the hypothesis, Pangaea broke apart and each metamorphism land mass drifted away from each other in different locations. At some point between 275 and 175 million years ago, Foliation generally caused by repetitive layering of sheet Pangaea began to separate. silicates (silica minerals with sheet-like structures) such as clay minerals, mica and chlorite. Initially, two giant continents were formed: Classification of Metamorphic Rocks - Laurasia which comprised the northern continents of today's times - Gondwanaland which comprised the continents in the present southern hemisphere. FOLIATED - it shows a layered or banded appearance due to the parallel alignment of elongated or platy minerals. The slow process of fragmentation and drifting continued until Common foliated metamorphic rocks are slate, the continents eventually reached their current position. The phyllite, schists, and gneiss. continents are not at rest, they are always moving and over - Gneiss (pronounced, nice). The foliation in gneiss is time will move and drift into entirely new continents over the striking Light-colored minerals segregate from dark next hundred years. ones, forming light and dark layers alternating with one another. Wegener aligned his theory with references from past authors with similar ideas like those of Eduard Suess (1831-1914) who is better known to have proposed the existence of Tethys Sea the only recognized body of water those ancient time, as he NON-FOLIATED recognized existence of Gondwanaland. do not exhibit foliation because they are commonly made of minerals which are neither platy or elongated. Example: Marble, Quartzite Did you know? Wegener's theory was not widely accepted by the scientific community for many years. It was initially dismissed because it Types of Metamorphism did not offer an acceptable hypothesis explaining the movement of the continent. Wegener could not explain what ◆ Contact an intrusion of hot, molten magma will change the force was driving the motion of the but Wegener provided rock when it comes in contact. Do not show foliation. strong evidence to support his Continental Drift Theory. ◆ Regional metamorphism large scale movements of Earth's crust cause a vast region of rock to sink into the Earth which experiences increased heat and pressure. Develop foliation or layered texture. EVIDENCE OF CONTINENTAL DRIFT THEORY Usually, seafloor spreading happens along mid- ocean ridges. Elsewhere, trenches are formed where one plates slides The apparent fit of the continents beneath another because the older seafloor rock eventually descends into trenches and is removed. Therefore, there is no The coastlines of the continents appear to fit together like the change in the overall volume and size of Earth. If the crust is pieces of puzzle, The apparent fit is even better when expanding along the oceanic ridges, it must be shrinking submerged coastlines are examined. In this diagram, significant somewhere else. overlap of the coastlines occurs only in the shaded areas because underwater sediments are extensively deposited. The concept of seafloor spreading was developed by geologists Harold Hess (1895- 1982) and Robert Dietz (1914- 1995). They coined the term "seafloor spreading" and showed it aligned with the unaccepted ideas of continental drift. Fossil Correlation Identical fossils have been found in the rocks found on coastlines the ocean. CONTINENTAL DRIFT THEORY - Mesosaurus lived in Africa and South America ALFRED WEGENER - Glossopteris lived in southern continents - Cynognathus lived in Africa and South America - Lystrosaurus lived in Africa Antarctica, India - As a young scientist, Wegener was curious about Earth's continents. - In 1910, Wegener formed a hypothesis which stated that 250 million years ago, all the continents were once joined together in a giant landmass. Rock and Mountain Correlation - He named this landmass PANGAEA. - this giant supercontinent was surrounded by a single Identical rocks and mountain structures have been found. giant sea known as the Panthalassa. - According to Wegener, Pangaea split up into smaller Paleoclimate Data/Past Climate Data continents. - Laurasia and Gondwanaland Coal and compacted sediments of tropical plants have been found in cold regions and glacial evidence (Glacial Striations/Scratches) have been found in warm regions. Theory of Continental Drift, which states that parts of the Earth's crust slowly drift atop a liquid core. The giant landmass, Seafloor Spreading Model Pangaea, drifted apart and formed the seven known continents today. Scientists estimated that the continents move anywhere from one centimeter to several inches per year. If the appearance of the Earth is drastically changing over time, are there any changes in the overall volume and size of the Earth? Evidence to Support the CDT Seafloor spreading is a continuous process where tensional forces on both sides of the plates caused them to constantly move apart. Magma rises to the surface from the mantle. In time, the magma is cooled by seawater and forms the oceanic Evidence from Landforms or The Continental Jigsaw crust. New rocks then form in this area. Since the newer rocks are younger in features, scientists are able to determine areas - The shapes of the continents seemed to fit together. of seafloor spreading because of the types and compositions Mountain ranges and other features also lined up. of new rocks on areas. Rocks from the separated plates would - South America and Africa fit together. have similar rock types and compositions usually of - India, Antarctica and Australia match one another. sedimentary type while the area at the center have mostly - Eurasia and North America completed the puzzle in igneous type. the North. Evidence from Fossils - Fossils from one continent matched fossil from other continents. - Wegener used both plant and animal fossils. - Fossilized leaves of an extinct plant Glossopteris were found on a 250- million-year-old rocks. These fossils were in the continents of South Africa, Australia, India and Antarctica which are now separated to each other by wide oceans. - Mesosaurus: a freshwater swimming reptile found in Africa and South America Evidence from Climate - Wegener looked at certain areas on Earth and their climates - He noted that the fossils he found on certain sections of Earth did not the current climate. SEAFLOOR SPREADING The mechanism that operates along the ocean ridge system to create new floor is called seafloor spreading. Harry Hess an American geologist together with Robert Dietz presented this hypothesis and he proposed that the seafloor is not permanent but is continuously being renewed. - Hess theorized that the ocean ridges are located above upwelling convection cells in the mantle. - The theory of the seafloor spreading provided the mechanism for the continental drift. Findings that Support the Seafloor Spreading - Rocks are younger at the mid-ocean ridge - Sediments are thinner at the ridge - Rocks at the ocean floor are younger than those at the continents.