Complex sentence: The Pierre Shale is the host formation for commercial oil deposits in the Florence-Canon City field in Fremont County, Colorado, and recently for natural gas in the Raton Basin in southern Colorado.
Split into simpler sentences: The Pierre Shale is the host formation for commercial oil deposits in the Florence-Canon City field in Fremont County, Colorado. More recently, natural gas has been extracted in the Raton Basin in southern Colorado.