They show that there was an ocean over the plains long ago, and fossils are always used to elaborate on the history of life/how it developed.
Metamorphism (the process called intrusion)
The best answer is reduction in acid rain.
Acid rain is rainfall which has been rendered acidic by pollutants in the atmosphere. This kind of rain is typically harmful to forests and lakes.
The main cause of acid rain is human activities. The burning of fossil fuels such coal in electrical generating plants and crude oil products such as gasoline and diesel in car engine releases sulphur dioxide and nitrogen oxide into the atmosphere.
These compounds mix with water very high up in the atmosphere and form acid pollutants which fall on the ground as acid rain.
Use of clean energy will eliminate burning of fossil fuels and thus no acid rain will be produced.
Because some states refused to ratify the Articles of Confederation.
