stratigraphy. geochronological scale.

acid; ancient; archaean; cambrian; chalky; coal; development; devonian; dinosaur; diplodocus; disappeared; earth; explosion; extinction; field; fossils; galaxy; geochronological; geology; glaciation; history; horsetails; house; hundreds; iii; jurassic; katharchi; land; long; mammoth; mill; millions; neogene; ordovician; paleogene; periods; permian; plaunas; prehistoric; proterozoic; quaternary; rain; reptiles; scale; scorpio; silurian; skull; stratigraphy; thousands; tractor; trees; triassic; universe; vector; years; geology