In areas where layers of coal and shale formed millions of years ago, there likely existed swampy forests. These environments were characterized by lush vegetation, warm and humid climates, and abundant rainfall. The dense growth of plants, such as ferns and club mosses, contributed to the formation of organic matter which gradually decomposed and transformed into peat bog. Over time, layers of sediment like mud and sand covered the peat, compacting it and transforming it into what we know today as coal. While shale, found alongside the coal layer, is the result of compacted mud layers from ancient river systems that transported sediments into these marshy, forested regions. Therefore, these environments featured landscapes with wetlands, thriving flora, and conditions similar to modern-day marshes and wet woodlands.