This paper describes the structural glaciology of the lower Fox Glacier, a 12.7 km-long valley glacier draining the western side of the Southern Alps, New Zealand. Field data are combined with analysis of aerial photographs to present a structural interpretation of a 5 km-long segment covering the lower trunk of the glacier, from the upper icefall down-glacier to the terminus. The glacier typifies the structural patterns observed in many other alpine glaciers, including: primary stratification visible within crevasse walls in the lower icefall; foliation visible in crevasses below the lower icefall; a complex set of intersecting crevasse traces; splaying and chevron crevasses at the glacier margins; transverse crevasses forming due to longitudinal extension; longitudinal crevasses due to lateral extension near the snout; and, arcuate up-glacier dipping structures between the foot of the lower icefall and the terminus. The latter are interpreted as crevasse traces that have been reactivated as thrust faults, accommodating longitudinal compression at the glacier snout. Weak band-ogives are visible below the upper icefall, and these could be formed by multiple shearing zones uplifting basal ice to the glacier surface to produce the darker bands, rather than by discrete fault planes. Many structures such as crevasses traces do not show a clear relationship with measured surface strain-rates, in which case they may be 'close to crevassing', or are undergoing passive transport down-glacier.

Seasonal variations in ablation and surface velocity were investigated on the lower Fox Glacier. Variations occur between summer and winter ablation, with surface velocity also showing marked seasonality. Recent advance has resulted in the glacier gaining around 200 m length since late 2004. Longer term, Fox Glacier appears linked to the Southern Oscillation Index, with positive glacier mass balances associated with negative Southern Oscillation Index (El Niño). An estimated glacier response time of approximately 9 -14 years suggests the current terminus advance was linked to mass gains in the mid-1990s. Recent collapses at the terminal face continue to prove a hazard at this busy tourist destination.

O) have potential within the structural glaciology field, but larger sample numbers than reported here may be required to establish isotopic contrasts between a broad range of ice facies and glacier structures.