Empirical and Theoretical Investigations of Sculpted Forms in Buckeye Creek Cave, West Virginia

Abstract

Sculpted forms play important roles in channel erosion, but the controls on their growth or appearance are uncertain. Empirical evidence from sculpted forms eroded into limestones within Buckeye Creek Cave, West Virginia, shows that types of sculpture morphology are determined by the types of flow or vortex structures present within sculptures during floods. Small hemispherical sculptures maintain constant form as they enlarge and occupy fixed locations on channel walls because of their association with joints, styolites, and bedding planes. Taking advantage of the systematic growth and stability of the sculptures, a geometrical model of sculpture growth is presented that relates the effects of sculpture size, form, and wall retreat to the relative erosion efficiencies and excesses required for sculpture growth. Numerical results obtained from the theoretical model reveal that small sculptures must erode more efficiently than large sculptures or they will be removed by wall retreat and that erosion rates must increase exponentially with increasing concavity. Relative to channel erosion, small sculptures must possess very high interior erosion rates where nearby surfaces are rapidly eroding. Therefore, small sculptures are unlikely to form or persist on rapidly eroding surfaces, and the rate of incision is an important control on the evolution of sculpted forms.