A least-squares solution utilizing photogrammetrically determined surf ace-velocity vectors (Reference BrecherBrecher, 1982) was used to compute contour maps of surface strain-rate components on Byrd Glacier. On a broad scale, the results suggest longitudinal extensive flow in the region between 40 and 10 km above the grounding zone, laminar flow in the vicinity of the grounding zone, and longitudinal compressive flow in the region between 10 and 50 km below the grounding zone where flow diverges and enters the Ross Ice Shelf. More localized gradients of longitudinal, transverse, and shear strain-rate suggest that flow is influenced by bedrock topography. Strain-rates along a longitudinal ice-thickness profile above the grounding zone support this contention. Relative extension in the transverse and longitudinal directions correlates well in two locations with bedrock highs and increased surface slope, while compression in the transverse and longitudinal directions correlates with a bedrock low and a decrease in the surface slope in another location.