TEMPERATURE AND BATHYMETRY OF ICE-CONTACT LAKES IN MOUNT COOK NATIONAL-PARK, NEW-ZEALAND

Several ice-contact lakes have formed in conjunction with twentieth ce ntury glacier retreat in Mt Cook National Park. They occupy overdeepen ed glacial valleys and are damned by terminal moraines and/or outwash heads. During the autumns of 1994 and 1995, the temperature and bathym etry of ''Maud lake'', ''Godley lake'', and Hooker Lake were surveyed. The near-glacier vertical water temperature profiles exhibited greate r temperature variation than those at the distal ends of the lakes. Th ermal stratification existed in Hooker Lake, whereas both Maud and God ley lakes were thoroughly mixed. Water temperatures in the latter were consistently between 3 and 4.5 degrees C, but most parts of Hooker La ke were cooler than 2 degrees C, with a minimum recorded temperature o f 0.2 degrees C. These contrasts are important because melting of subm erged parts of glacier termini is significant for ablation rates and f or the dynamics of calving termini. All the lakes are steep sided and deep. Maud and Godley lakes approach 100 m in depth, whereas Booker La ke has a maximum recorded depth of 136 m. Extensive flat floors in Mau d and Godley lakes probably reflect rapid sediment accumulation follow ing glacier retreat. Water depth at the termini of iceberg-calving gla ciers is known to correlate strongly with rates of iceberg production and hence the rate of glacier retreat. However, given the substantial water depths through which these glaciers (and also the neighbouring T asman Glacier) have retreated, they appear to be more stable than comp arable glaciers in other countries. The subaqueous geometry of all the glacier termini comprises a projecting ramp of glacier ice. All the l akes are being enlarged by glacier retreat except Maud lake, which has been reduced in size since 1995 by the advance of Maud and Grey Glaci ers.