Coastal marshes must increase elevation to maintain themselves in the face of sea-level rise. At the same time processes at their borders determine areal extent by fostering erosion or progradation at the seaward edge and transgression or stalling landward. Two major plant communities are recognized in many salt marshes: the high marsh and low marsh. At the mainland portion of the Virginia Coast Reserve we consider the high marsh to be dominated by Distichlis spicata and Spartina patens with prominent patches of Juncus roemerianus. Spartina alterniflora dominates the low marsh. One might expect a natural progression over time from high to low marsh as sea-level rises based on decreased sedimentation away from creeks, instability of organic soils within the high marsh and relative vigor of plants within different inundation patterns. The transition from high to low marsh might include increased sedimentation and exposure to wrack disturbance, and loss of organic-rich soil strata. However, studies at Upper Phillips Creek marsh of vegetation cover for nearly 18 years, experimental manipulations of tidal flooding for 10 years, and surface elevation change for 12 years demonstrate patterns that complicate the expected progression. For example, J. roemerianus patches are quite capable of maintaining themselves within the low marsh, and rates of surface elevation increases within the transitional area between marsh zones rival that of the low marsh. Periodic disturbances and multi-year sea-level variation may contribute to these changes. Historical contingency and stochasticity of marsh plant growth provide opportunities for both resistance to change and even reversal of expected trends.