Measurements of temperature in snow along a vertical profile during the onset of spring melting are used to calculate spatial and temporal temperature gradients and terms of the conduction equation with an internal energy-production term are calculated. Heat-transfer information is combined with stratigraphic observations made during melting and allow detailed determination of the timing and location of heterogeneous water movement and of refreezing. Internal energy production is interpreted as

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... latent heat of refreezing of percolated meltwater. Times and locations of flow and refreezing of meltwater are calculated and compared to Stratigraphic observations of layering and changes in density and liquid-water content. Sequences of melt, piping, layering and refreezing seen in calculations and in stratigraphy demonstrate retarded flow at fine-to-coarse transitions, flow along such transitions and refreezing at the transitions to form ice layers. Downslope flow is also observed in the absence of an impermeable horizon to redirect flow from the vertical.