Fig. 2: Optical televiewer logs.
From: Influence of the grounding zone on the internal structure of ice shelves
Full optical televiewer logs for JP-21 (A) and SI-47 (E). Vertical traces are superficial artefacts from the drilling process. B and F show examples of near-horizontal layering present for the top 80 m of JP-21 and 103 m of SI-47, respectively. C and G show examples of more steeply dipping layers at depth for JP-21 and SI-47, respectively. D and H show examples of crevasse traces at JP-21 (cutting across other fainter ice layers) and SI-47 (containing a bubble-free ice layer), respectively, indicated by red arrows. Layer delineations for panels D and H are shown in Supplementary fig. 2. All logs shown were recorded moving up the borehole – the downward log was indistinguishable from the upward log in each borehole – and are orientated to true North. A and E are shown in greyscale to normalise operator-controlled lighting changes made during logging; all other panels are shown in true colour at varying scales (note the differing y-axis ranges).
