The number of people per square mile is the population density
Originally it was made from cardboard and wood but now its stone and brick
<span>a reference point for measuring elevation</span>
1. Fracking
2. Air pollutants.
3. Decomposition of organic matter e.g. in landfills.
4. <span>Chlorofluorocarbons </span>mainly in refrigerants and air conditioners.
Amount of energy released by the earthquake, and distance from the epicenter. hope that helps!
