Have to be careful not to use these faster than we can replenish them
Soil Mixture of living and nonliving things (tiny rocks, minerals, organic matter, water and air) that provides habitat for plants and organisms. Takes thousands of years to form Hot, humid climates form larger amounts more quickly Dry climates form small amount over longer periods Soil only “renewable” as long as living organic matter stays fertile.
Room and pillar method : miners dig “rooms” in the coal beds and leave “pillars” to help support the mine roof. Once most of the coal is removed from the room, the pillars are removed and the roof falls in
Longwall Method : a cutting head moves back and forth across a coal seam, causing pieces of coal to fall onto conveyor belts. Special supports moved along wall as it is mined. Roof falls in as work down the wall and supports are moved.