Glacier-specific hypsometry changes suggest a mean rise in ELA of 135 m but there is wide inter-glacier variability. The largest proportional changes for individual outlet glaciers are associated with the loss of ice falls and consequent disconnection of tributaries. We show that the major outlet glaciers have lost at least 110 km² or 19% of their LIA area and 14 km³ or 18% of their LIA volume until 2006. The LIA maximum ice-covered area was 568 km² and the LIA ice volume was between 61 km³ and 91 km³. Here, we reconstruct the maximum glacier extent and ice surface of Jostedalsbreen, which is the largest ice mass in mainland Europe, during the Little Ice Age (LIA) ∼ 1740 to 1860. Mountain glaciers and ice caps are undergoing rapid mass loss but rates of present-day changes and models of future projections both lack long-term (centennial-scale) context. Overall, this sequence, consistent with sediment fills recorded elsewhere across South Island, suggests recurrence of processes from different glacial advances and the role of topographic constraints on maintaining lake positions.
Two infrared stimulated luminescence ages were obtained from the glaciolacustrine sediments and, whilst the dating has some limitations, the sediments pre-date both the global and local Last Glacial Maximum. We identify seven lithofacies, from which a five-stage palaeoglaciological reconstruction of depositional and glaciotectonic events is proposed: (i) ice-marginal advance and deposition of outwash gravels in lithofacies (LF) 1 (ii) ice-marginal recession and the development of an ice-contact lake, manifest in rhythmite deposition and iceberg rafting of dropstones (LF 2), followed by a depositional hiatus (iii) ice-marginal recession recorded in ice-proximal aggradation of glaciofluvial hyperconcentrated flows (LFs 3, 4) (iv) ice-marginal advance documented by glaciotectonic disturbance and localized hydrofracturing, coeval with the deposition of delta foresets and a subglacial diamicton/till (LFs 5, 6) (v) final stages of ice-marginal recession and deposition of outwash gravels in LF 7. We present the first detailed investigation of sediments along the southwestern shores of Lake Tekapo, South Island. The sediment-landform imprint of this glacial system, however, offers insight into ice-marginal processes that chronological control cannot. The extent of the Southern Alps icefield in New Zealand is well-constrained chronologically for the last glacial cycle.
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