煤系地层
coal formation
coal seam
coal seam strata
coal measure strata
coal measures strata
coal formation stratum
coal stratum
coal -bearing formation
coal measures
coal-bearing strata
Coal-bearing formations
Coal-bearing Formation
coaly stratum
coal-bearing beds
Lithologic characteristics
spore-pollen assemblage
coaly-stratum
煤系软弱(夹)层
Adhesion and proliferation
煤系原料
treated carbon powders from coals
煤系硬质高岭(土)岩
hard kaolin (kaolinite) in coal measures strata
coal-measure hard kaolin(kaolinite
煤系盖层
overlying strata of coal measures
煤系泥岩
coaly mudstone
source rocks in coal-measures
陆相煤系
continental coal measure strata
inland coal measures