Earth Science – Terms and Definitions based on Fariel, R. - Hinds, R. - Berey,D.: Earth Science, Addison-Wesley 1987 Chapter 1 Studying the Earth Section 1 The Earth - Earth Sciences -The Scientific Method direct observation Information received by one or more of the senses. instrument A tool used to extend our senses when making observations. indirect observation An observation that requires the use of an instrument. data A collection of observations. classifying Grouping similar objects or events. physical property A feature of a substance in itself. chemical property A feature of the way one substance reacts with another substance. inference An interpretation of observations. hypothesis Possible answer to a problem, based on observations. theory Explanation based on strong evidence that several generally accepted hypotheses are correct. An explanation for observed phenomena that has a high possibility of being true. (Pl) lithosphere The rigid outer shell of the earth, 70 to 125 or more kilometers thick. (The solid part of the earth.) hydrosphere The entire liquid or water part of the earth. atmosphere Envelope of gasses surrounding the Earth, held by gravity. The blanket of air, dust, water droplets, ice particles, etc. that completely covers the earth's lithosphere and hydrosphere. biosphere The region where all life is found. crust The outer layer of rock, forming a thin skin over the earth´s lithosphere. geology The science concerned with the earth's lithosphere. petrology The part of geology that specializes in rocks. hydrology The science concerned with the earth's entire hydrosphere. meteorology The science concerned with the earth's atmosphere. oceanography The science concerned with the oceans. astronomy The science concerned with stars and planets. Section 2 Measuring Circumference The distance around a circle or ball. Density The mass of 1 cm^3 of a material. Derived unit A unit of measure obtained from two or more base units. Diameter A straight line that crosses a circle through the center. Formula A group of symbols that make a mathematical statement. A representation of a substance using symbols for its constitutional elements. Mass (hmotnost) The amount of material in something (the same everywhere). Radius - pl. radii the distance from the center to the edge of a circle. SI Initials for International System of Units. Volume The amount of space that an object takes up or can be filled with. Weight The pull of gravity on nearby objects. Numbers and Fractions Numbers: ordinal (1,2,3) cardinal (1.,2.,3.,) even (2,4,6..) odd (1, 3, 5..) Numerals: Arabic Roman (II, VII) Fractions: a half, a third, a fourth/a quarter, a fifth, decimal point, the tenth, the hundredth, the thousandth Symbols: percent, infinity, (not)equal to, greater than, less than Operations: addition (plus) – result/answer subtraction (minus) - remainder multiplication (multiplied by, times) division (divided by) power (squared, cubed ) root (square/cube/fourth) Geometry Draw the lines, angles and shapes: Lines: straight parallel curved spiral perpendicular Angles: right obtuse acute reflex Shapes: square, rectangle, rhombus, parallelogram, diagonal triangle – base circle – circumference arc diameter radius Segment sector ellipse Three-dimensional Shapes: cube sphere cylinder cone pyramid Remember the expressions with the stress on the second syllable: obtuse, acute, diagonal, triangle, rectangle, diameter, circumference, subtract Check the correct pronunciation: Arabic, Roman, equal, quotient, radius, sphere, cylinder, the thousandth, curved, angle, subtract, Wide – width – widen, deep –depth – deepen, high – height [ai], weigh – weight [ei], strong – strength(en), long – length(en) Section 3 Mapping the Earth´s Surface compass An instrument for locating magnetic north. contour interval Difference between contour lines. contour line Line indicating the same elevation. elevation Height above sea level. equator Line that circles the earth at 0° latitude. globe A physical model of the earth. graphic scale of distances Line divided into units of distance. hachures Short lines that indicate direction of slope. latitude Distance north or south of the equator. longitude Distance east or west of the prime meridian. magnetic declination Distance from true to magnetic north. magnetic north Direction toward the North Magnetic Pole. map projection An attempt to represent the earth´s curved surface on a flat surface. map A flat representation of the earth´s surface. meridian A north-south line that crosses the equator. North Geographic Pole Point where all meridians meet. North Magnetic Pole The North Pole indicated by a compass. parallel East-west line parallel to the equator. prime meridian The imaginary north-south line that passes through Greenwich, England. scale Ratio of map distances and actual distances. topographic map A map that shows land features. topography Elevations and shapes of land features. true north Direction toward the North Geographic Pole. Chapter 2 Earth Materials Section 1 Minerals matter Anything that takes up space and has mass. atom The smallest complete part of an element with all the properties of that element. element A substance that contains only one kind of atom. compound A substance made up of two or more elements joined together in fixed proportions. impurities Atoms of elements other than the key elements of a mineral. mineral A compound that is natural, inorganic, a crystalline solid, and made up of key elements. crystalline solid A solid substance whose atoms are locked together into fixed patterns. A substance in which the atoms are arranged in a regular, repeating, orderly pattern. (Pl) inorganic Not organic; formed, for the most part, without the help of plants and animals. crystal The shape produced when mineral grains have freedom to form in any direction. silicate minerals Minerals containing silicon and oxygen. nonsilicate minerals All minerals that are not silicates. heft A rough-estimate weight test for minerals. cleavage The ability of a mineral to break into smooth, parallel surfaces. luster The way that a mineral reflects the light. streak The color of the powder of a mineral against a white background. fracture The manner in which a mineral breaks (that does not have cleavage). Section 2 Rocks rock A mixture of minerals that is beneath all soil and water on the earth's surface. Naturally formed, consolidated material composed of grains of one or more minerals. (There are a few exceptions to this definition.) (Pl) igneous rock Rock that is formed from solidification of magma (hot melted materials). lava What magma is called after it reaches the surface of the earth. magma Liquid rock melt that is found in some places beneath the earth's surface. sedimentary rock Rock that is formed from sediments. metamorphic rock Rock that is formed deep within the earth's crust when minerals and rocks are changed by very great heat and pressure which changes the crystal structure. mineral composition A list of the minerals that make up a rock. texture The pattern made by the size, shape, and arrangement of the particles that are in rock. rock cycle The process by which rock is changed from one class to another. Section 3 Using Earth Materials ore Any mineral or rock from which a needed substance can be removed cheaply enough and easily enough. mine The place that ore comes from. fossil fuels Fuels formed from the remains of plants and animals that lived and died long ago. petroleum A liquid fossil fuel. natural gas A fossil fuel that is a gas. trap A kind of blockage formed by nonporous rock that traps petroleum and natural gas. petrochemicals Chemical products made from petroleum. coal A solid fossil fuel. peat A brown, lightweight, unconsolidated or semi-consolidated deposit of plant remains. (Pl) solar energy Energy from the sun. hydroelectric energy Electricity produced by generators powered by moving water. geothermal energy Energy powered by heat from deep within the earth's crust. atomic energy Energy that is derived from the atoms of certain earth materials. fission Atomic energy that is produced when certain large, unstable atoms are made to split apart to form atoms of a different element. fusion Atomic energy that is produced when atoms of an element are joined together to form atoms of a different element.