The valley is a crescent-shaped depression, a part of the ridge-and-valley or folded Appalachians. The Susquehanna River occupies the southern part of the valley, which is notable for its deposits of anthracite. These have been extensively mined. Deep mining of anthracite has declined throughout the greater Coal Region, however, due to the greater economics of strip mining. Parts of the local mines had already shut down because some coal beds were on fire and had to be sealed; but the exodus of mining companies came quickly following the legal and political repercussions of the 1959 Knox Mine Disaster—when the roof of the Knox Coal Company's mine under the river collapsed. The Pocono Mountains, a ridgeline away, are often visible from higher elevations to the east and to the southeast of the Wyoming Valley.