Roaring Run begins in a deep valley on Forkston Mountain in Forkston Township. It flows south through its valley for several tenths of a mile before turning south-southeast. The stream continues flowing through its deep valley in this direction for more than a mile before receiving South Branch Roaring Run, its first named tributary, from the. Its valley then broadens slightly and it turns southeast for several tenths of a mile before entering Noxen Township. Here, the stream turns east-northeast for a short distance before east-southeast and receiving the tributary Newton Run from the. The creek then leaves its valley and turns southeast for several hundred feet before turning south. A few tenths of a mile further downstream, it crosses Pennsylvania Route 29 and reaches its confluence with Bowman Creek. Roaring Run joins Bowman Creek upstream of its mouth.
Tributaries
Roaring Run has two named tributaries: Newton Run and South Branch Roaring Run. Newton Run joins Roaring Run upstream of its mouth and drains an area of. South Branch Roaring Run joins Roaring Run upstream of its mouth and drains an area of.
Hydrology
The alkalinity of Roaring Run upstream of the tributary South Branch Roaring Run is. Downstream of South Branch Roaring Run, the concentration increases to.
Geography and geology
The elevation near the mouth of Roaring Run is above sea level. The elevation of the stream's source is between above sea level. In its lower reaches, Roaring Run flows through a band where the surficial geology consists of alluvium. This area is flanked by areas with a surficial geology consisting of alluvial terrace and alluvial fan. Further upstream, the alluvium continues and is flanked by alluvial fan, Wisconsinan Ice-Contact Stratified Drift, Wisconsinan Till, and bedrock consisting of sandstone and shale. The surficial geology near the stream's headwaters features Wisconsinan Till and bedrock. In the Holocene Period, sediment from Roaring Run has forced Bowman Creek's channel to remain on the south side of its valley. This causes Bowman Creek to cut into bedrock, forming Evans Falls downstream of the mouth of Roaring Run.
Watershed
The watershed of Roaring Run has an area of. The stream is entirely within the United States Geological Survey quadrangle of Noxen. Part of it is approximately from the village of Forkston. The entire length of Roaring Run is on private land that is closed to access. The stream is located in the vicinity of the community of Noxen. Roaring Run is one of the major tributaries of Bowman Creek.
The drainage basin of Roaring Run is designated as a High-Quality Coldwater Fishery and a Migratory Fishery. Wild trout naturally reproduce in the stream from its headwaters downstream to its mouth. From its headwaters downstream to the confluence of South Branch Roaring Run, a distance of approximately, Roaring Run is designated by the Pennsylvania Fish and Boat Commission as Class A Wild Trout Waters for brook trout. From South Branch Roaring Run downstream to its mouth, a distance of approximately, Roaring Run is classified as Class A Wild Trout Waters for both brook trout and rainbow trout. Roaring Run is the only wild brook trout/rainbow trout fishery in Pennsylvania.