Underground coal mines in the Pacific Northwest had large appetites for wood products due to the nature of local mining. Unlike Eastern coal mines of flat seams and rock ceilings, those in King and Pierce Counties typically mined coal with pitches from 25º to 90º. This meant coal was above the miner and needed to be secure from collapse. To keep mines safe elaborate timbering was undertaken requiring a steady stream of lumber. When digging underground tunnels miners placed posts and cross-beams in successive sets to hold up the roof of the mine. Rough cut lagging (i.e. planks) were placed between timber sets providing a safe canopy overhead.