acid precipitation: - rain or any other form of precipitation (snow, for example) that is acidic. Acidic means there are high leavels of hydrogen ions which can be harmful to plants and animals.

Arctic Circle: - an imaginary line of latitude around the Arctic regions. It is near (but to the south) of the North Pole.

Arctic Ocean: - smallest ocean in the world. Surrounds the North Pole between North America and Eurasia.

arid: - a way of describing a climate that is dry and does not receive much rainfall

Atlantic Ocean: - the second largest ocean in the world. It separates North and South America on the west from Europe and Africa on the east.

bank: - a stretch of rising land at the edge of a body of water.

bay: - body of water partially enclosed by land.

bays: - bodies of water that are partially enclosed by land.

biome: - a community characterized by dominant forms of plant life or climates. Examples include deserts, grasslands, forests, woodlands, and others.

biomes: - are communities characterized by dominant forms of plant life or climates. Examples include deserts, grasslands, forests, woodlands, and others.

canal: - an artificial waterway created for travel, shipping, or other reasons. Canals often connect places, such as two bodies of water or other transportation systems like roads or railroads.

cardinal direction: - a term used to describe all four primary directions (north, south, east and west).

cartographer: - a person who makes maps

channel: - bed of a stream or river, typically the deepest part of the river or harbor. Usually a broad strait that connects two seas or other bodies of water.

cliff dwellings: - houses made INSIDE of shallow caves and under rock overhangs along canyon walls or on the cliff sides of a mesa

coal mine: - a place where coal is removed from the earth.

coal seam: - a stratum (or wide layer) of coal that is thick enough to be mined to make a profit.

coal seams: - stratums (or wide layers) of coal that are thick enough to be mined to make a profit.

continental climate: - a climate that experiences all four seasons and is found in the interior (the middle) of major continents, away from the ocean.

continental divide: - the "backbone" of a continent. In North America, it runs from the Northern tip of Alaska all the way south to New Mexico. It moves along the Rocky Mountains, which separate the eastward-flowing waters from the westward-flowing waters.

coordinates: - provide the exact location of a specified area on a map. The coordinates provide the degrees of longitude and latitude. Coordinates help people locate specific areas on a map.

dam: - a wall that is built to hold back the water of a creek, stream, or river. Dams may also be used to generate hydroelectric power, to provide water supply to a town or city, to control flooding, or to create recreational areas or habitats for wildlife.

dams: - walls that are built to hold back the water of a creek, stream, or river. Dams may also be used to generate hydroelectric power, to provide water supply to a town or city, to control flooding, or to create recreational areas or habitats for wildlife.

daylight saving: - a way states and countries change their clocks in spring and fall to make better use of daylight. It moves an extra hour of daylight to afternoon during March to October. This helps people who work outside. Daylight saving time also conserves energy, moving activities into the daylight so we do not need to use lights. Not all places participate in daylight saving time.

daylight saving time: - a way states and countries change their clocks in spring and fall to make better use of daylight. It moves an extra hour of daylight to afternoon during March to October. This helps people who work outside. Daylight saving time also conserves energy, moving activities into the daylight so we do not need to use lights. Not all places participate in daylight saving time.

democracy: - a government that is run by the people or by their elected representatives. The United States is a democracy because we elect our president and other leaders.

desert: - a sandy and dry landform and biome. Deserts typically have extreme temperatures: either hot or cold.

deserts: - are sandy and dry landforms and biomes. Deserts typically have extreme temperatures: either hot or cold.

district: - a geographical or political division (similar to a state).

dormant: - inactive, but not extinct (used to describe volcanoes)

drought: - a severe water shortage (very little rain).

dust storm: - a windstorm that lifts up and blows around dust, sand, and even clouds.

dust storms: - windstorms that lift up and blow around dust, sand, and even clouds.

earthquake: - shaking and vibration on the surface of the earth. An earthquake can be a result of underground movement along a fault plane or from volcanic activity.

earthquakes: - shaking and vibration on the surface of the earth. Earthquakes can be a result of underground movement along a fault plane or from volcanic activity.

East Coast: - the coast that borders the Atlantic Ocean.

economy: - how people spend, earn, and exchange money to run businesses, pay for things, and build the community.

elevation: - the altitude (or how high) a location is above sea level.

elevations: - the altitudes (or how high) locations are above sea level.

equator : - an imaginary line on the earth's surface that is positioned halfway between the north pole and the south pole. The equator divides the earth into the northern hemisphere and the southern hemisphere.

forests: - an area with a lot of trees, plants, and brush

fossil fuel: - a non-renewable energy source that was formed a LONG time ago (300 million years) from the remains of plants and animals. There are three main forms of fossil fuels: oil, natural gas, and coal.

fossil fuels: - non-renewable energy sources that were formed a LONG time ago (300 million years) from the remains of plants and animals. There are three main forms of fossil fuels: oil, natural gas, and coal.

four corners: - the area where the corners of the states of Colorado, New Mexico, Arizona, and Utah meet together.

freshwater port: - a place on a "freshwater" waterway with facilities for loading and unloading ships. Freshwater refers to any water that does not contain salt (remember, oceans contain salt).

geology: - the study of the history of the planet Earth, its structure, and formation. Geologists study rocks and other materials that make up the planet Earth, both on the inside and on its surface.

Grand Canyon: - a canyon located in the state of Arizona. It is a steep-sided gorge carved by the Colorado River. Most of the Grand Canyon is located in the Grand Canyon National Park, one of the first national parks in the United States.

grasslands: - land with a lot of grass, such as a prairie or meadow

Great Plains: - a vast prairie region of the United States that includes parts of 10 states: Colorado, Kansas, Montana, Wyoming, Texas, South Dakota, Oklahoma, North Dakota, Nebraska, and New Mexico.

green: - environmentally aware, interested in preserving and protecting the environment

gulf: - a small portion of the sea or ocean that is partly enclosed by land. Gulfs are larger than bays.

hemisphere: - half of a sphere.

hydroelectric power: - power (electricity) generated through the use of the gravitational force of falling or flowing water.

infrastructure: - the underlying base or foundation of a location, organization, or system

inland port: - a port that is located on an inland waterway (not having access directly to large seas or oceans).

island: - land that is surrounded on all sides by water.

islands: - land that is surrounded on all sides by water.

Kilauea: - an active volcano located in Hawaii.

landform: - any natural formation of rock and dirt found on the Earth. Examples of landforms include mountains, deserts, plains, and many others.

latitude: - the lines that run across (east and west) a map. Lines of latitude measure degrees via north or south. The equator is at 0 degrees latitude.

longitude: - lines that run up and down the map (north and south). These lines are used to measure degrees east or west from the prime meridian. The prime meridian is located at 0 degrees longitude.

map coordinates: - numbers that provide the exact location of a specified country or other area. The coordinates provide the degrees of longitude and latitude. Coordinates help people locate specific areas on a map.

map scale: - a graphic or line that shows the relationship between the distance on a map and the corresponding distance on the earth. For example, 1 inch may equal 500 miles. This allows users to calculate the approximate distance between two locations on a map.

Marine west coast: - the climate typically found along the west coasts at the middle latitudes of all the world's continents, and in southeastern Australia. These areas have somewhat cool summers and comparatively cool winters.

marshlands: - a type of wetland that has frequent or continuous floods. Marshlands typically have shallow water and include grasses and many other plants.

mesa: - a flat-topped area of land high above the surrounding land, usually with cliff-like sides, appearing like a "table" above its surroundings.

mesas: - flat-topped areas of land high above the surrounding land, usually with cliff-like sides, appearing like a "table" above its surroundings.

moderate: - a climate that doesn't have extremely cold winters or hot summers.

National Park: - a piece of public property (land) owned by a national government for preservation.

natural resources: - any substance that is made by nature and used to enhance the lives of living things. Some examples of natural resources include sunlight, minerals, soil, and water.

naturally flowing: - flows without the assistance of anything. Naturally flowing rivers typically flow towards another river, sea, or ocean.

Navaho Nation: - the name given to the Native American people who inhabit large reservation lands in three US states: Utah, New Mexico, and Arizona. As a whole, the Navaho Nation is the most populous contemporary Native American groups in the United States. They are noted as skilled potters, weavers, and silversmiths.

northern hemisphere : - the half of the planet Earth that is north of the equator. The northern hemisphere contains 90% of the human population and most of the land on the Earth.

orographic lift: - when elevated terrain, such as mountains, acts as a barrier to the flow of air. When the air ascends (or goes up) a mountain slope it gets cooler. When it cools, that causes clouds and precipitation. At the same time warm air is rising from the plains. When the cold air and warm air meet, the atmosphere becomes unstable and thunderstorms occur.

Pacific Ocean: - the largest ocean in the world.

peninsula: - a piece of land that is bordered by water (on three or more sides), but is not an island. A peninsula is attached to a larger body of land but sticks out into the water.

permafrost: - ground that is permanently frozen.

plateaus: - an elevated and level piece of land. Also called a tableland.

polar climate: - a climate which is too cold and dry to support the growth of trees.

political map: - map that shows the governmental boundaries between states, provinces, countries, and other man-made divisions. Political maps often include locations of major cities (another man-made government), and typically large bodies of water.

pollution: - the act of contaminating (accidentally or on purpose) air, water, or other spaces with harmful substances.

port: - a place on a waterway with facilities for loading and unloading ships (cargo, passengers, etc.).

portage: - a way for boats and/or ships to carry supplies between two waterways.

prairies: - large, flat, rolling areas with grassland that is mainly treeless.

prime meridian: - the imaginary line that runs up and down a map or globe. It is found at 0 degrees longitude. This imaginary line runs vertically through the United Kingdom, France, Spain, western Africa, and Antarctica. The prime meridian divides the world into the eastern hemisphere and western hemisphere.

recession: - a decline in the economy, so fewer things are sold, less is bought, jobs are often lost, and trade with other countries slows down.

renewable resource: - any natural resource that can be replenished naturally within a relatively short time. Examples include wood or solar energy.

renewable resources: - any natural resource that can be replenished naturally within a relatively short time. Examples include wood or solar energy.

reservation: - an area of land set aside by the United States government for Native Americans

ridges: - geological features that have a continuous elevational crest for a significant distance. They may also be called hills or mountains.

ring of fire: - a circle that encompasses the Pacific Ocean. In that circle, many volcanic eruptions and earthquakes occur. There are over 450 volcanoes in the ring of fire. Sometimes even tsunamis occur in the ring of fire.

scale: - shows the relationship between the distance on a map and the corresponding distance on the earth. For example, 1 inch may equal 500 miles. This allows users to calculate the approximate distance between two locations on a map.

Sierra Madre Oriental mountains: - a mountain range in northeastern Mexico, spanning 1000 km (about 600 miles). The highest point is Cerro San Rafael, at 3700 meters above sea level. This is NOT the same Sierras that are in California!

southern hemisphere : - the half of the planet Earth that is south of the equator. The southern hemisphere contains all of Antarctica and Australia, most of South America, and part of Asia and Africa.

temperate: - a climate that provides warm summers and mild winters. The temperatures do not typically get extremely hot or cold.

time zone: - how the time of day is determined throughout the world. There are 24 regions on the globe (loosely divided by longitude).

tributary: - a small river or stream that flows into a larger river or other body of water.

tropical: - a climate with high temperatures and a decent amount of rainfall. Tropical climates are usually located between the Tropic of Cancer and the Tropic of Capricorn, closer to the equator than cooler, temperate climates.

tundra: - a treeless area with very little vegetation and frozen ground beneath the surface.

valley: - lowland between mountains or hills

valleys: - lowlands between mountains or hills

vegetation: - all of the plant life in a region

volcano: - an opening in the earth's crust. HOT molten lava, ash, and gases are ejected from a volcano.

watershed: - the area of land that catches snow and rain and then drains into a stream, creek, marsh, lake, or other waterway.

west coast: - the coast that borders the Pacific Ocean.

woodlands: - large land area covered by trees and shrubs