Glacial geomorphology of the tableland east of the Andes between the Coyle and Gallegos river valleys, Patagonia, Argentina

Figures & data

Figure 1. Location map of the study area. Topography is shown by shaded and colored SRTM elevation data. Topographic profiles along transects shown in Figures 4 and 5 are noted and the position of the dated lava flow underlying the GPG (Mercer, 1976) till. Rectangles with dashes lines show the location and extent of subscenes of Figures 7 and 8.

Figure 2. Map of southern South America showing the extent of regional maps made by previous authors and the area mapped in this study.

Figure 3. Isolated erratic boulders on a moraine ridge, most of them Andean in origin.

Figure 4. Topographic profile across a moraine belt composed of prominent individual ridges. Transect A–A′ location is indicated in Figure 1.

Figure 5. Morainal topography on the tablelands. (a) Gently undulating topography of moraine ridges seen from one of the moraine forming belts. (b) Terrain profile along the line of sight of Figure 5(a). The relative level among these moraines is the largest in the glacial landscape.

Figure 6. Low, elongated and rounded frontal moraine ridge in the northeast corner of the study area (seen from east).

Figure 7. Grayscale SRTM elevation data subscenes. (a) Crosscutting contacts between moraines of Glacial Unit I (I) and Glacial Unit II (II); note the smooth topography of Glacial Unit I. (b) Crosscutting contacts between moraines of Glacial Unit I (II) and moraines of Glacial Unit III (II). White arrows indicate where truncation can be clearly seen. Location shown in Figure 1.

Table 1. Summary of ridge morphology and boulder content for moraines in the northeast corner and northern and southern halves of the map areas.

Glacial unit	Location on the map	Maximum relief (m)	Ridge morphology	Boulder content	Map polygon color
I	NE corner	10	Isolated rounded ridges – highly dissected – few km long	Poor and partially buried	Brown
II	North half	20	Isolated ridges – somewhere highly dissected-tens km long	High and visible	Orange
III	South half	25	Grouped ridges – severe gullying – highly continuous	High and visible	Yellow

Figure 8. Fault scarp along the northern margin of the Río Gallegos valley, where triangular facets are still recognizable.

Figure 9. Scoria cone overrun by glaciers and degraded by cryogenic processes. A huge erratic boulder at the slope foot is pointed out by the arrow.

Mercer, J. (1976). Glacial history of Southernmost South America. Quaternary Research, 6, 125–166. doi:10.1016/0033–5894(76)90047–8

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