Veins of coal are actually layers in rock strata, usually sandwiched between layers of sandstone. Veins can be 20 feet high or so thin that miners would have to crawl between the sandstone layers to get the coal out. Anthracite is so hard it has to be blasted out foot by foot. The wooden pillars did not actually hold up the tunnel ceiling. They were to warn, by creaking and cracking, if the ceiling is going to cave in. Pillars of coal held the ceiling up and it was the most dangerous job in the mine to pick away at these supports, as these guys are doing, although one got "danger pay" for doing it. Next.