58 
Portion of element: Crest and upper flanks of 
the slope. 
Vegetation: Dryas integrifolia, Cas- 
siope tetragona, \ichens and 
mosses. 
Slope: 10-13% 
Depth in cm: 
0-15 Very dark brown (10 YR 2/2) 
organic loam; massive to weakly 
granular in the upper few centi- 
meters; gravel skeleton ~ 5%; free 
carbonates throughout; carbonate 
accumulation on most skeletal frag- 
ments to a depth of 7.5 cm; roots 
common; boundary abrupt, wavy. 
15-25 Dark brown to brown (10 YR 4/3) 
medium sand; massive; pebbles few; 
roots common; boundary abrupt, 
irregular. 
Yellowish brown (10 YR 5/6) fine 
and medium gravelly coarse sand; 
massive to somewhat loose; larger 
skeletal fragments have carbonate 
crusts on their underside and silt 
coats on top; roots few. 
25-30+ 
The carbonate accumulations beneath the 
surface lag as well as on the underside of the 
skeletal fragments within the profile are indica- 
tive of the xeric environmental conditions in 
which they formed. The deposition of silt coats 
on gravel fragments at depth suggests seasonal 
downward movement of fines, probably due to 
infrequent, heavy summer rains. The exposed 
position of the soils precludes a snow cover 
sufficient to provide meltwater. The net water 
movement is upward, however, as in soils of map 
unit 2. 
The final soil type recognized on Plate | 
occurs in frost medallions (non-sorted circles) ; it 
is designated as soils unit 7 and classified as a 
Pergelic Cryaquept. These soils have a textural 
range from loam through loamy sand to sand. 
They occur as circular areas ranging from un- 
vegetated mineral soil to those completely cover- 
ed with a vegetation assemblage distinct from 
the surrounding meadow tundra (soil map unit 
3). Those lacking vegetation undergo intense 
seasonal frost heaving and desiccation. Most 
frost medallions have some vegetation cover, and 
those which have been stable for an extended 
period have an organic horizon up to several 
centimeters thick. Beneath the organic horizon (if 
present), is a horizon which is normally above 
the water table and in which oxidation is the 
dominant process. Below this horizon, seasonal 
fluctuations in the water table produce alternat- 
ing oxidizing and reducing conditions which 
impart a mottled appearance to the soil. Below 
this zone, reducing conditions dominate. 
Thaw depth beneath the frost medallions is 
commonly double that of the surrounding mea- 
dow tundra, in part, because the medallions lack 
the insulation of the thicker organic horizons of 
soil unit 3. The occurrence of frost medallions is 
restricted to areas of meadow tundra. This asso- 
ciation may be further restricted to meadow 
tundra areas underlain by sandy textured, miner- 
al materials. Their aerial extent ranges widely 
from a few percent of the surface to near 50%. 
The following profile is representative of soil 
unit 7. 
Soil type: Pergelic Cryaquept. 
Polygonal surface with 
neither high- nor low- 
center polygons. 
Terrain-relief 
element: 
Portion of element: Not applicable. 
Vegetation: Saxifraga oppositifolia; 
Carex spp.; moss; lichens 
(Thamnolia sp. and Dacty- 
lina sp.). 
Slope: 4% 
Depth in cm: 
0-5 Very dark greyish brown (10 YR 
3/2) organic loam; soft, weak, fine 
aggregate structure; roots common; 
boundary abrupt, irregular or 
broken. 
5-9 Yellowish brown (10 YR 5/6) to 
yellowish red (5 YR 4/6) silty fine 
sand; intermixed with dark greyish 
brown (10 YR 4/2) silty medium 
sand; massive; fine nodular carbon- 
ates near 5 cm; occasional pea grav- 
el; roots common; boundary 
abrupt, irregular. 
9-14 Dark greenish grey (5 GY 4/1) silty 
medium. sand; massive; strong, 
