Across
- 4. Pollution that starts in one country and crosses boundaries into other countries
- 8. The movement of plates below Earth's surface
- 9. The study of human populations, including how they change due to births, deaths, aging, and migration
- 12. A large group of people who share a common history and culture.
- 14. A force that unites people and countries
- 18. A force that divides people and countries
- 19. Natural forces that change Earth's physical features, including forces that build up and wear down Earth's surface
- 20. A political unit that controls a particular territory
- 21. A river and all the streams that flow into it
- 22. The total fertility rate needed for a population to replace itself
- 23. The number of old and young dependents who don't work compared with the working-age population.
Down
- 1. A form of international cooperation in which countries give up some control of their affairs as they work together to achieve shared goals
- 2. A group of people in a country who share a unique culture and identity
- 3. An independent state, or country, who people mostly share a common identity
- 5. Rain that can damage the environment because it contains acid from factory smoke and car exhaust
- 6. Feelings of loyalty and pride towards one's nation or ethnic group
- 7. A group of countries that acts as a single market, without trade barriers between member countries
- 10. The formation and eruption of volcanoes
- 11. The average age that a person in a given population can expect to live to
- 13. The creation and movement of glaciers
- 15. A form of energy that comes from nuclear reactions
- 16. The gradual wearing away of Earth's surface by the action of wind, water, ice, and gravity
- 17. The average number of children a woman in a given population will have in her lifetime (Abbreviation)