George VI Ice Shelf: moraine featuresThe western edge of the ice shelf has a series of unusual debris ridges, an "ice-shelf moraine", which we studied in detail. The moraine comprises irregular ice-cored ridges of debris originating from both Palmer Land and locally. Especially noteworthy are granite erratics transported from a large ice stream opposite, Bertram Glacier in Palmer Land, right across the ice shelf. Moraine formation is linked to melting out of basal ice that was incorporated within the ice-marginal foliation. |
![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/1_george_vi_ice_shelf_ablation_point_moraine_DSC_5166.jpg) General view of the widest part of the ice-shelf moraine, looking NNE towards the distant mountains of Palmer Land. | ![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/2_george_vi_ice_shelf_gneiss_largest_DSC_4702.jpg) Bethan Davies standing next to a 4 metre-long gneiss boulder near Moutonnée Lake. This boulder was transported across the ice shelf from Palmer Land. | ![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/3_george_vi_ice_shelf_moraine_DSC_4411.jpg) Ice-shelf moraine, showing sharp ridge crest, near Ablation Lake. The sediment (diamicton) is emerging from a thin vertical debris layer parallel to foliation, and forms a veneer less than a metre thick at the surface. | ![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/4_george_vi_moutonnee_lake_moraines_DSC_5085.jpg) Prominent ridge in the ice shelf-moraine just south of Moutonnée Lake. Note also melt-pool and moderately dipping foliation in the ice beyond. |
![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/5_george_vi_ice_shelf_ablation_point_thrust_moraine_DSC_5164.jpg) Ice-shelf moraine at Ablation Point, showing stacking of several debris layers as a result of localized thrusting. | ![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/6_george_vi_ice_shelf_moutonnee_bench_DSC_4677.jpg) A bench with outer moraine ridge indicates that the ice shelf reached a significantly higher level in the past. | ![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/7_george_vi_moraine_diamicton_DSC_4466.jpg) Typical sediment in the ice-shelf moraine: diamicton, a poorly sorted sediment with clasts up to boulder size and a silty matrix. | ![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/8_george_vi_ice_shelf_granite_DSC_4673.jpg) A large angular granite erratic near Ablation Lake. Originating from Palmer Land, this block may have been transported englacially or supraglacially. |
![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/9_george_vi_ice_cliff_DSC_4424.jpg) Ice cliff near Ablation Lake, showing the debris layers that represent the source of the moraine material. | ![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/10_george_vi_ice_shelf_boulder_on_pond_DSC_4708.jpg) A large granite boulder from Palmer Land has slid down the moraine onto the frozen surface of a pond. | ![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/11_george_vi_ice_shelf_granite_gneiss_DSC_4663.jpg) A large granite-gneiss boulder from Palmer Land showing a rusty veneer (iron oxide) indicative of chemical weathering. | ![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/12_george_vi_ice_shelf_minibraids_sand_DSC_4881.jpg) Well sorted sand on the surface of George VI Ice Shelf near Ablation Lake. This represents aeolian sediment that has been reworked by a supraglacial stream. |
![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/13_george_vi_ice_shelf_table_DSC_4858.jpg) Glacier table formed where a boulder has protected the underlying ice from ablation. This example occurs at the bed of a drained supraglacial lake near Moutonnée Lake. | ![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/14_george_vi_ice_shelf_chemical_weathering_DSC_5187.jpg) A chemical precipitate (gypsum?) resulting from the weathering of mudstone within the ice-shelf moraine. | ![George VI Ice Shelf: moraine features George VI Ice Shelf: moraine features](icons/15_george_vi_split_boulder_DSC_4428.jpg) In an older ice-shelf moraine, this granite boulder near Ablation Lake has been split in two by frost action. | |
Photos Michael Hambrey, November and December 2012. |