Cenozoic means "recent life." You are living during the Cenozoic Era. Many tectonic events have taken place in the last 66 million years! They have shaped the world as we know it today.
Western North America has been active during the Cenozoic Era. Huge blocks of crust have been uplifted. The Rocky Mountains were formed. Large basins formed next to the mountains. They were filled with nearly three kilometers of sediment from the eroded mountain land.
Basins in Wyoming filled with swampy river deposits. Eventually they formed great amounts of coal. These coal deposits begin close to the surface and go nearly 50 meters deep. This coal is very valuable because it burns cleanly. This is due to its low sulfur content.