"Layer Blocks" are the types of blocks that make up the layers underground. There are 15 blocks that are known to make up these layers. Some of the blocks that are excluded are the blocks only exclusive to biomes (e.i. snow, sand, etc.). The blocks that make up he layers underground are grass, dirt, clay, sandstone, limestone, basalt, andesite, dacite, diorite, tuff, serpentine, gabbro, granite, komatiite, marble, rhyolite, and bedrock respectively in order of appearance by increasing depth.