Figure 7. Toposequences illustrating geomorphology, vegetation, elevations, soil stratigraphy, and permafrost occurrence. (See Figure 6 for key to lithofacies.) - continued

g. Transect 4 in the Delta Creek Floodplain.

Figure 7 (Cont'd).

exposed ridges supported bearberry dwarf scrub tun-

kettle depressions. Organic matter accumulation also

dra and open low mesic shrub birchericaceous scrub,

was highly variable. Well-drained upland sites without

both of which had abundant lichens. Poorly drained soils

permafrost had open paper birch forest and closed tall

on slopes had permafrost and supported black spruce

willow scrub. Poorly drained sites with permafrost had

forests. Basins had thick organic matter accumulations

open low mixed shrubsedge tussock bogs and open

and supported subarctic lowland sedge wet meadows.

black spruce. Subarctic lowland sedge moist meadows,

Within the Lower Delta Creek Lowlands (Transect

an uncommon vegetation type, occurred in somewhat

1), the geomorphology was dominated by hilly

well-drained, fine-grained lacustrine material in drained

retransported deposits associated with eroding Tertiary

kettle basins.

Nenana Gravel deposits and by organic deposits (Fig.

Within the Jarvis Creek Glaciated Lowlands

7f). Well-drained soils on crests supported closed shrub

(Transect 6), the geomorphology was dominated by

birchericaceous scrub, while poorly drained soils on

young moraines associated with the Donnelly glacia-

gentle slopes supported black spruce forests, closed

tion and old moraines associated with the Delta glacia-

shrub birchericaceous scrub, and open low mixed

tion. On the young moraine (Transect 6a), soils also

shrubsedge tussock bog. Basin bogs with thick organic

were highly variable as described above, although or-

accumulations in swales support an unusual type of open

ganic accumulation was small (Fig. 7d). Vegetation on

low ericaceous scrub bog.

steep, gravelly, south-facing slopes had a unique veg-

Within the Delta Creek Floodplain (Transect 4), the

etation type of open quaking aspen dwarf tree scrub,

geomorphology was dominated by glaciofluvial

presumable because of the severe wind exposure.

outwash riverbed deposits, inactive cover deposits, and

Lower, wetter slopes supported closed shrub bircheri-

abandoned floodplain deposits (Fig.7g). The transect

caceous scrub and open black spruce forest. Ponds and

extended onto an old moraine. The excessively drained,

pond margins supported pondlily and subarctic low-

gravelly soils of the active riverbed were barren to par-

land sedge wet meadow, respectively. On old moraines

tially vegetated with Dryas dwarf scrub tundra. The

(Transect 6b), the topography was much more subdued,

well-drained loamy soils with interbedded silts, sands,

but gravelly soils were still common (Fig. 7c). More