Sentences with phrase «ancient soils showed»

In 1992, a team from the University of New Mexico reported that ancient soils showed extremely high levels of carbon dioxide 440 million years ago, an age of primitive sea life before the advent of land plants and animals.

Not exact matches

With the exception of the fertile river valleys along which agriculture began, civilizations generally lasted 800 to 2,000 years, and geoarchaeological studies have now shown a connection between soil erosion and the decline of many ancient cultures.