deposits and the results of landslide activity. It appears that HWSG symbols are meant to show locations of landslides as point features. The GDS symbols are meant to show landslide features at a larger scale, as line and polygon features; at smaller scales, areas of landslide deposits are polygons outlined by contacts. If the HSWG symbols are meant to represent the landslide deposits, then the closest correlation is with symbols 17.11 (Landslide deposits), 17.56 (Active, reactivated, or historically active debris flow…), 17.57 (Dormant-young debris flow …), 17.58 (Active, reactivated, or historically active landslide…), 17.59 (Dormant-young landslide…), and 17.65 (Debris-slide slope…).
Avalanche (#5) may correlate with a GDS symbol; however, because this term refers to an event that involves (and likely was caused by) snow and ice, geologists rarely can specify with confidence that a deposit (especially pre-modern) was the result of an avalanche. More commonly, the earth-material deposits that resulted from an avalanche are described by geologists according to their physical characteristics. Based on those criteria, the HSWG Avalance symbol could be correlated with those specified for Landslide, especially the debris-flow symbols; however, this isn’t recommended.
Subsidence (#8) correlates with GDS symbols in Section 23 (Miscellaneous Uplift and Collapse Features), specifically 23.9 (Collapse structure or sinkhole, too small to draw to scale), 23.10 (Collapse structure or sinkhole, drawn to scale), and 23.11 (Crater outline, unspecified origin).
2. Correlation of HSWG Infrastructure symbols (see ) with GDS symbols:
Commercial infrastructure – Landfill (#25) and Superfund site NPL (#27) may correlate with GDS symbols in Section 20 (Hazardous Waste Sites), although the correlation is not entirely clear.
Energy Facilities – symbols #32 through 37 may have some correlation with GDS symbols in Section 19 (Natural Resources) and symbols 30.3.1 through 30.3.15 in Section 30 (Topographic and Hydrographic Features). The HSWG symbols focus on large infrastructure such as energy generation and distribution plants, whereas the GDS symbols focus on the energy resources and individual well and mine locations. If the HSWG has not already considered this, the GDS suggests that portraying the locations of subsurface mine locations, and oil&gas fields and wells, might prove worthwhile, in consideration of their security implications.
Transportation – symbols #57-73 may have some correlation with GDS symbols in Section 28 (Transportation Features) and 30 (Topographic and Hydrographic Features). The GDS symbols are the traditional symbols long used on topographic base maps. They are quite detailed, and are provided to in order to assist geologists in preparation of digital base maps upon which geologic maps are portrayed. The only specific HSWG symbol found in the GDS standard is Lock (#64), which correlates to three GDS symbols for “Canal Lock”, found as 30.2.9, 30.2.10, and 30.2.11.
Water Supply –