(ABSTRACT)Headwater streams drain the majority of the landscape, yet little is known about their form and function in comparison to lowland rivers. Better understanding of their morphology and sediment transport processes will improve understanding of landscape evolution and promote a more complete view of fluvial systems. Therefore, the goal of my project was to determine controls on headwater channel form and function in the humid, moderate-relief drainage channel slope values, and grain size. These variations are due to differences in bedrock resistance at the formation level as well as at short wavelengths. Bedrock also controls channel form through its influence on local and regional base level, channel initiation processes, and log jam abundance. Hydraulic geometry, steam competence and bankfull flow recurrence also vary greatly between and within channels. This variation is due to the high sensitivity of the streams to hillslope influences such as bedrock resistance, boulder influx, and soil profile development. Increases in bedrock resistance within a channel create knickpoints that lower stream competence and slow hilllslope erosion. Stream competence is generally higher in channels with erodable bedrock and lower in channels with resistant bedrock, but most channels could entrain the majority of the grains on their bed at 2-year stormflows. Bankfull is a larger, less frequent flow than the 2-year storm at very small drainage areas (<0.4 km 2 ), but is approximately a 2-year recurrence flow at larger drainage areas. Bankfull occurs less frequently in North Carolina Blue Ridge streams, due to deep soils that form on metamorphic bedrock under an more intense precipitation regime and have high rainfall storage capacity. Results indicate that variability is a fundamental feature of headwater streams and that they do not follow channel slope, hydraulic geometry, and bankfull relations developed in lowland river systems.

The Baltimore terrane, the Baltimore Mafic Complex (BMC), and the Potomac terrane are telescoped tectonostratigraphic packages of metasedimentary and meta-igneous rocks that record the geologic history of eastern Maryland from 1.2 Ga to 300 Ma. These terranes provide insight into the understanding of the rifting of Rodinia and the initial amalgamation of eastern Laurentia. The oldest of these rocks are exposed as gneiss domes in the Baltimore terrane, with gneissic Grenvillian crust overlain by a metasedimentary cover succession believed to have been deposited during Rodinian rifting and the formation of the Iapetus ocean. These rocks are interpreted to be analogous to the Blue Ridge sequence in western Maryland. Late Cambrian ultramafites and amphibolites of the BMC discordantly overlie the Baltimore terrane to the east and north, and may represent ophiolitic oceanic crust obducted over eastern Laurentia continental rocks as an island-arc collisional event during the Taconian orogeny. To the west, a thick assemblage of schist, graywacke, metadiamictite, and ultramafic bodies comprises the Potomac terrane, a polygenetic mélange that may have formed in an accretionary wedge during Taconian subduction and collision with the Laurentian continental margin. The Pleasant Grove fault zone marks the Taconian suture of these accreted terranes to Laurentian rocks of the central Maryland Piedmont, and preserves evidence of dextral transpression during the Alleghenian orogeny in the Late Pennsylvanian.

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