The Permian Phosphoria Formation of the western United States represents some 15 million years of sedimentation reaches a thickness of 420 metres and covers an area of 350,000 km 2.
The Permian Phosphoria Formation of the western United States represents. Some 15 million years of sedimentation reaches a thickness of 420 metres. Some 15 million years of sedimentation covers an area of 350,000 km 2.