Types and Parts of Maps

Types of Maps

• A contour line connects points of equal elevation on a topographic map.
• The difference in elevation between two side-by-side contour lines is called the contour interval.
• A geologic map shows the distribution, arrangement, and type of rocks located below the soil.
• Geologic maps may also show geologic features such as fault lines.

Parts of a Map

• Remote sensing is the process of gathering data about Earth using instruments mounted on satellites, airplanes, or ships.
• Landsat satellites record reflected wavelengths of visible light and infrared radiation from Earth’s surface, and then computers convert the information into digital images.
• Landsat data are used to study pollution, the movements of Earth's plates, and the melting of glaciers and ice caps.
• The OSTM/Jason-2 satellite uses radar to measure and map sea surface height.
• Radar uses high-frequency signals that are transmitted from the satellite to the surface of the ocean.
• A receiving device then picks up the returning echo as it is reflected off the water.
• SeaBeam uses sound waves sent from a ship toward the ocean floor.
• A receiving device picks up the returning echo when it bounces off the seafloor.

The Global Positioning System

• GPS technology is used extensively in navigation by airplanes and ships.
• GPS receivers help people in everyday life to find a destination or determine their current location.

The Geographic Information System

• The Geographic Information System (GIS) uses a worldwide database to create layers, or “themes,” of information that can be placed one on top of the other to create a comprehensive map.
• GIS map layers remain linked to the original information, so if the original information changes, the GIS layers also change.
• The result is a map that is always up-to-date.

Atoms

• Matter is anything that has volume and mass.
• All matter is made of substances called elements.
• An element is a substance that cannot be broken down into simpler substances by physical or chemical means.
• Elements are made up of atoms.

Atoms (cont'd)

• All atoms consist of smaller particles—protons, neutrons, and electrons.
• The center of an atom is called the nucleus, which is made up of protons and neutrons.
• A proton is a tiny particle that has mass and a positive electric charge.
• A neutron is a tiny particle with approximately the same mass as a proton, but it has no electrical charge.
• The number of protons in an atom’s nucleus is its atomic number.
• The sum of the protons and the neutrons in an atom’s nucleus is its mass number.

Isotopes

• All atoms of an element have the same number of protons.
• The number of neutrons of an element’s atoms can vary.
• Atoms of the same element that have different mass numbers are called isotopes.
• The atomic mass of an element is the average of the mass numbers of an element’s isotopes.

Electrons in Energy Levels

• The electrons in the outermost energy level, called valence electrons, determine the chemical behavior of the different elements.
• Elements with the same number of valence electrons have similar chemical properties.
• Elements that have full outermost energy levels are highly unreactive, which means that they do not combine easily with other elements.

Compounds

• A compound is a substance that is composed of atoms of two or more different elements that are chemically combined.
• Compounds have different properties from the elements of which they are composed.

Covalent Bonds

• A chemical bond is the force that holds together the elements in a compound.
• The attraction of two atoms for a shared pair of electrons that holds the atoms together is called a covalent bond.

Ionic Bonds

• An ionic bond is formed by the attraction between oppositely charged ions.

Metallic Bonding

• In a metallic bond, the positive ions of the metal are held together by the attraction to the negative electrons moving among them.

States of Matter

• Solids have a definite shape and volume.
• Solids are crystalline structures because the particles of a solid are arranged in regular geometric patterns.
• Solids melt when they absorb enough thermal energy to cause their orderly internal crystalline arrangement to break down.
• Liquids take the shape of the container they are placed in, but they have a definite volume.
• Liquids solidify at the same temperature they melt (freezing point).
• When a liquid is heated to the boiling point and absorbs enough thermal energy, vaporization occurs, and the liquid becomes a gas.
• Gases have no definite shape or volume unless they are restrained by a container or a force such as gravity.
• When a gas is cooled to the boiling point, it releases thermal energy and becomes a liquid (condensation).

Bowen’s Reaction Series

• Bowen discovered two main patterns, or branches, of crystallization.

Fractional Crystallization

• When magma cools, the first minerals that crystallize are the last minerals that melted during partial melting. This process is called fractional crystallization.

Mineral Composition of Igneous Rocks

• Igneous rocks are classified by their mineral compositions.
• Basaltic rocks (mafic rocks) are dark-colored, have lower silica contents, and contain mostly plagioclase and pyroxene.
• Granitic rocks (felsic rocks) are light-colored, have high silica contents, and contain mostly quartz and feldspar.

Texture

• When lava cools so quickly that crystals do not form, volcanic glass is the result.
• When magma cools slowly below Earth’s surface, there is sufficient time for large crystals to form.
• Intrusive rocks can contain crystals larger than 1 cm.

Igneous Rocks as Resources

• Valuable ore deposits often occur within igneous intrusions.
• Valuable ore deposits may also occur as veins in the rocks surrounding intrusions.