Date of Graduation

1999

Document Type

Thesis

Degree Type

MS

Committee Chair

J. Steven Kite

Abstract

Rapids occur where supercritical flow conditions are present (Kieffer, 1985). Supercritical flow, resulting from a local decrease in stream depth or acceleration in flow, is commonly produced where voluminous surficial deposits or bedrock outcrops constrict the stream channel. Mapping at 1:10,000-scale shows that most rapids in the lower New River Gorge, are a result of surficial deposits, including valley-wall mass movement, tributary debris fans, and alluvium. Few rapids occur at bedrock outcrops. Half of the rapids are predominantly the result of valley-wall mass movement, including debris flow, rock fall, and debris slide/complex failures. Tributary debris-fan deposits, derived from debris flows along tributary streams, are responsible for five rapids. Bedrock outcrops account for four of the 22 rapids. Alluvial debris bars cause the remaining two rapids. The distribution of rapids in the lower New River Gorge is comparable to those in other canyons. The Grand Canyon and the lower New River Gorge both reflect the importance of mass-movement deposits in the formation of rapids. However, most rapids in the Grand Canyon are located at tributary debris fans. In contrast, rapids in the lower New River Gorge are located at local mass-movement deposits. The origin of rapids does not appear to correlate with the difficulty rating. This lack of correlation is most likely a result of the subjective nature of the difficulty class rating.

Share

COinS