ABSTRACT The Fernow Experimental Forest (the “Fernow”) is an 1860-ha (4600-acre) research forested watershed in Parsons, West Virginia, USA. The Fernow has been in operation since 1934 and has historically been the site of timbering and silvicultural research programs. Beginning in the 1950s, a water quality research program was established in the Fernow to assess the effects of different forestry management techniques on water quantity and quality. As a result, most peer-reviewed research from the Fernow has focused on water quality data directly related to forestry efforts with little mention of the effects of geology, hydrogeology, or climate on water resources in the Fernow. Further, the Fernow is representative of Appalachian headwater mountain watersheds and is a protected and secure research site in the greater Monongahela National Forest. This, in combination with the long-term data records from the water research program, make the Fernow an ideal location for further geologic and hydrologic investigations in forested mountain watersheds. The geology of the Fernow is dominated by moderately dipping Paleozoic-aged strata with local karst features (e.g., springs) occurring in one unit. The hydrology of the Fernow consists of intermittent and perennial streams that are reactive to seasonal weather patterns. This field guide serves as an overview of the geology and hydrology of the Fernow and surrounding region to be used as a teaching and recruitment tool to advance the geologic understanding of Allegheny Mountain headwaters.