Ashland coalfield boundary; assessment area for the Knobloch coal resource unit (knbndg.shp)

This ArcView shapefile contains a polygon representation
of the Ashland coalfield, Montana, as defined in the USGS
National Coal Resource Assessment (NCRA) project. This
theme was created specifically for the National Coal
Resources Assessment in the Northern Rocky Mountains
and Great Plains Region.

本ArcView 形状文件（ArcView shapefile）包含蒙大拿州阿什兰煤田的多边形要素表达，该煤田的范围由美国地质调查局（USGS）国家煤炭资源评估（NCRA）项目界定。本图层专为北落基山脉与大平原地区的国家煤炭资源评估项目制作。