The mining process that takes place in the PRB is called surface mining. First, the topsoil is removed. The material above the coal (overburden in mining jargon) is then removed to expose the coal. The overburden is placed into a previously mined pit.
The exposed coal is then scooped out. Rocks, ash, sulfur, and other contaminants are cleaned out of the coal. Blasting and crushing reduces the coal to smaller pieces that can be loaded onto trains for transport. Trains bring the coal to power plants throughout the country.
The Surface Mining Control and Reclamation Act (SMCRA) requires mining companies to reclaim the mined land. The mined land is filled in with overburden, and the topsoil is replaced. Native seeds are planted on the reclaimed land. The whole process is overseen by environmental engineers and state and federal agencies to ensure compliance with laws. Lands disturbed by coal mining must be restored to a condition that can support the uses it could support before mining (or even make the land better).
In the close-up images, the mined land seems to move over time. As the mining and beginnings of the reclamation process take place, we can see the digging and backfilling occurring.
(See the animations in the subsection called "Animations" to see more images and to see this process happen over the 30-year time period.)