Figure 1: Glacial geomorphology and GPR profiles at Site 1.
From: Discovery of relict subglacial lakes and their geometry and mechanism of drainage
(a) Location of the palaeo-subglacial lakes in Alberta, Canada. The coloured elevation gradient is the extent of the LiDAR data from which we conducted the mapping. Site 1 is shown in b and Site 2 is shown in Fig. 2a. CIS=Cordilleran Ice Sheet. (b) Glacial geomorphology of Site 1 showing the location of a palaeo-subglacial lake (flat spot) connected by a number of inflowing and outflowing subglacial meltwater channels. Note the downstream transition of the main subglacial meltwater channel into an esker. Lines 1–5 are a GPR profile across the flat spot (Supplementary Fig. 5). Line 15 is a GPR profile across a meltwater channel (Supplementary Fig. 4). Lines 23–34, 27–28 and 30 are GPR lines shown in c–e. See Supplementary Fig. 1a for mapping of flat spots, meltwater channels, eskers and outwash fans. (c) GPR long profile of esker running downstream from the top of the macroform. (d) GPR cross-profile of esker showing reflectors that drape a poorly attenuated core. (e) GPR long profile of esker downstream of the macroform.
