Terrain types and associated soils

The spatial distribution of soils in the study area will be illustrated briefly by a number of soil/permafrost site descriptions. Some are from the site type discussions of Welch and Smith 1993 for Ivvavik National Park, while others are from the Taiga Net Wetlands satellite image classifications web site (Taiga Net, Hawkings and Eckert 1999d). All these sites are unglaciated and thus of particular research value to Canadian soil studies. (Canadian soil studies are usually dominated by the fact that most of Canada was covered by ice sheets as recently as ten thousand years ago.) The progression of sites will be from the most barren terrain to rich biotic areas of the Old Crow Flats. Colour versions of the black and white Figures 6.10 and 6.11 and the additional colour figures referred to are found in the Supplement. They cannot be included here due to the restriction in the number of colour illustrations.

Rockland - Bedrock and Felsenmeer (Welch and Smith 1993 page 5.16) Bedrock exposures are usually linked to frost-shattering block fields, a thin accumulation of usually angular blocks of rock with no fine sediment, known as felsenmeer, and the coarse, angular boulders of the upper parts of talus slopes (Figure 6.10a Figure 6.10b , see also Geomorphology, Chapter 4, Figure 4.9b and Supplement W4.4). The soil classification of these rockland areas is nonsoil. It has no soil profile development and less than 10 cm of unconsolidated particles finer than gravel.	Figure 6.10b Click photo to enlarge and see other photos.
Colluvial Hillslopes (Welch and Smith 1993, page 5.6 ) Talus-covered slopes grade upward into rounded summits. Slope inclinations are 15 to 35 E. Surface materials are generally rubbly to blocky on these thin colluvial slopes. (Figure 6.10c and Figure 6.10d, and W4.34). Although the landscapes of these colluvial hillslopes have evolved over tens of millions of years, they are also the product of weathering and mass wasting in a dynamic and on-going equilibrium. Consequently, soils tend to be shallow and much disturbed by natural forces, and so there is little profile development, suggesting Regosolic Turbic Cryosols ( Figure 6.6a).	Figure 6.10 c and d Click photos to enlarge.
Dry Barrens (taiga_net/wetlands/oldcrow/class16, Hawkings and Eckert 1999b) Most commonly found on exposed alpine areas or gravel bars along rivers, these dry barrens are unvegetated or partially vegetated dry soils. Small areas are also found in drained lake basins. Some areas of Cottongrass tussock tundra may be found in this class if there is a high percentage of frost boils. These dry barrens occur in the vicinity of the town of Old Crow (see Hydrology , Figure8.4a and Supplement tnclass16).
Pediments and lower Fans and Aprons (Welch and Smith 1993, page 5.14) Soil textures on the pediments are loamy, ranging from clay loam to sandy loam. These materials are produced by long-term weathering and transport by surface runoff (Figure 6.10e and Figure 6.10f, and W4.3, W4.17 and W4.42). Drainage is imperfect to poor and soil everywhere is periodically saturated. Soils are strongly cryoturbated and often have gleyed resulting in Gleysolic Turbic Cryosols (Figure 6.6c).	Figure 10e. Click to enlarge and see other photos.

Fluvial Plains (Welch et al. 1993, page 5.17) Alluvial materials, usually sands and gravels, occupying low-lying sites of less than 1 degree slope are found on floodplains, deltas, river terraces and outwash plains which make up this group in Vuntut National Park. On floodplains and deltas, frequent inundation and ongoing fluvial processes of erosion and deposition (Hydrology Chapter 8, Section 3Di and Figure 8.7) result in soil textures from pure sands to clean washed gravel. These floodplain sites can have non-cryosolic soils (soils without permafrost within two meters of the surface) due to the melting of permafrost under flowing rivers or recent river beds. Orthic Regosols occur where materials are devoid of soil weathering or buried organic layer, and Cumulic Regosols (Figure 6.6) where distinct buried surface layers are in evidence. On terraces (Figure 6.11a, Figure 6.11b) and outwash plains, textures are more uniform across the plain, ranging from sandy loams to sandy gravels. Many river terraces are at sufficient elevations above the river that the soils are well drained but where drainage is impeded they remain wet. Orthic Turbic Cryosols are the most common soil (Figure 6.6b).

Glacio-lacustrine Lake Beds (taiga_net/wetlands/oldcrow/class2, Hawkings and Eckert 1999d) Present lakes that have exposures of clays originally deposited by the periglacial lake (which occupied the Old Crow area prior to 12,000 years ago) are extremely turbid (muddy) and show up vividly on satellite images. The turbid lakes may clear up during protracted periods of calm. These thermokarst lakes (created by melting of permafrost) are discussed in Geomorphology, Chapter 4, Section 3Ciiif and Hydrology, Chapter 8, Section 3C.

Old Crow River Bluffs (Hughes et al. 1989, and Schweger 1989) Stratigraphic sections of exposed river bluffs show the vertical distribution of soils and their parent materials. The composite section from the Old Crow River Bluff (6.11c) studied in detail by geologists and palaeontologists shows a peat layer at the surface which overlays a layer of fluvial silt and sand. Under this is the layer of glacial-lacustrine clay deposited by the pro-glacial lake which filled the area prior to 12,000 years ago (see also Geomorphology, Chapter 4, Figure 4.6a and Section 3Biiic). At Ch'ijee's Bluff (Figure 6.11d), the organic layer is missing and the silt and sand layer overlaying the glacio-lacustrine clays is exposed to the surface.

Paleosols (Tarnocai 1990, p 368 and 1987c) The Old Crow paleosols buried under Late Wisconsinan lake sediments (more than 12,000 years old) developed in a permafrost environment with gleyed horizons, mottles, cryoturbated features, patterned ground and ice wedges. The ice wedge formations found in these paleosols indicates the presence of a climate colder than now (see Figure 6.12 and Supplement Soil Section 2).

Soil Profiles and Permafrost Features (Tarnocai 1987, Hettiger et al. 1973). Detailed soil profiles for areas in the vicinity of the study area are discussed by Tarnocai (1987) and Hettinger et al. (1973). These are included in the Supplement, Soil Section 2 and 3. Once soil studies have been undertaken within the Park these early detailed studies can be related to actual conditions found within the Park area. Permafrost features are discussed in detail in Geomorphology, Chapter 4 Figure 4.10 Figure 4.11 Figure 4.12.

Terrain Types and Associated Soils: Selected Examples