Period during which source of great coal deposits in West Virginia Pennsylvania Ohio and Illinois existed?

The period during which the source of great coal deposits in West Virginia, Pennsylvania, Ohio, and Illinois existed is known as the Carboniferous Period. This period lasted from approximately 359 million years ago to 299 million years ago and is characterized by the formation of extensive coal swamps in the regions mentioned. During this time, lush vegetation thrived in warm and humid climates, giving rise to the accumulation of organic matter that eventually transformed into coal.