Date of Award

Spring 1998

Document Type


Degree Name

Master of Science (MS)


Ocean/Earth/Atmos Sciences

Committee Director

G. Richard Whittecar

Committee Member

D. A, Darby

Committee Member

J. H. Rule


An alluvial fan complex blankets a portion of the Rockfish Valley in Nelson County Virginia, located along the eastern slope of the Blue Ridge Mountains. The seven-km2 field area contains three mappable relict alluvial surfaces (Qf1, Qf2, and Qf3) and one modern surface (Qa1), each of which is underlain by fluvial deposits dominated by greenstone and charnokite cobbles. The four surfaces were mapped according to topographic position and degree of stream dissection. Alluvial deposits underlying each surface were characterized using a 3-part clast weathering scale based on greenstone clast weathering rinds and using soil development criteria (clay content, Munsell colors, and total free iron in the argillic horizon).

Cluster and discriminant function analyses of the soil development and rock weathering data strongly support the mapping criteria used to distinguish the three relict alluvial surfaces. The clast weathering scale developed for this study provided especially useful distinctions between different deposits. The strong separation of surfaces based upon the relative age criteria indicates fan surfaces were deposited during separate episodes widely spaced in time.