The Colorado River has been forming the Grand Canyon in Arizona for at least 6 million years. During this time, the river has slowly caused erosion of the rock. As the rock eroded, soil eroded as well, and plant populations have had to adapt to live in increasingly
rocky conditions. The river continues to deepen and erode the canyon at a rate of a few milimeters per year. What geologic principle
is this an example of?
OA. catastrophism
ОВ. uniformitarianism
OC. geographism
OD. gradualism

Match your vocabulary word to its definition. 1. emigration 2. immigration 3. migration 4. overpopulation 5. sustainable development 6. under population 7. unsustainable development 8. urbanization the movement from one place to another the number of people exceeds the available natural resources in an area leaving one's homeland to settle in a new place the increase in the population of a city the movement of people to a new country the ability to meet current needs without reducing the ability to meet future needs resources being used up at a faster rate than they can be replenished birth rate insufficient to replace the existing population