FROST PROBLEMS AND PHOTO INTERPRETATION 
Polygons in (a) Sorted and (b) Non-sorted 
(including frostcrack polygons, ice-wedge 
polygons, tussock-birch-heath polygons, des- 
iccation polygons), Steps in (a) Sorted and 
(b) Non-sorted and, finally, Stripes in 
(a) Sorted and (b) Non-sorted. 
Washburn defines Sorted circles as pat- 
terned ground whose unit component, the 
mesh, is dominantly circular and has a sorted 
appearance commonly due to a border of 
stones surrounding finer material. Debris is- 
lands are sorted circles occurring amid blocks 
or boulders. Non-sorted circles are patterned 
ground whose mesh is dominantly circular 
and which has a non-sorted appearance due 
to the absence of a border of stones, such as 
that characterizing sorted circles. Sorted nets 
are patterned ground whose mesh is inter- 
mediate between that of a sorted circle and a 
sorted polygon and has a sorted appearance 
commonly due to a border of stones surround- 
ing finer material. Non-sorted nets are pat- 
terned ground whose mesh is intermediate 
between that of a non-sorted circle and a non- 
sorted polygon and has a non-sorted appear- 
ance due to the absence of a border of stones 
such as that characterizing a sorted net. 
Sorted polygons are patterned ground whose 
mesh is dominantly polygonal and has a 
sorted appearance commonly due to a border 
of stones surrounding finer material. Non- 
sorted polygons are patterned ground whose 
mesh is dominantly polygonal and has a 
non-sorted appearance due to the absence of 
  
Fic. 9. Low-oblique of non-sorted polygons (ice- 
wedge polygons) on the coastal plain, Arctic Slope, 
Alaska, southeast of Point Barrow, in the con- 
tinuous-permafrost zone. Part of thaw lakes top 
right and left foreground, a rounded thaw pond 
left center. Most of the raised polygons are high- 
centered with low ridges around the margin of the 
flat-topped polygon. They are confined to rela- 
tively well drained areas between lake basins. The 
troughs around them are rather wide and some- 
times deep as well. Be careful to avoid false relief 
with the troughs standing out as ridges. (From a 
color photo taken by the author August 15, 1955. 
14 
  
Fic. 10. Low-oblique of non-sorted polygons (ice- 
wedge polygons) on Arctic coastal plain near 
Point Barrow, in the continuous-permaífrost zone, 
Alaska. Flat tundra surface. Part of a great thaw 
lake at top, angled thaw ponds (high center). 
Most of the polygons are high-centered, separated 
by shallow troughs. In left foreground and right 
center there are several low-center polygons with 
ponds developing in their center. (Photo by the 
author.) 
a border of stones such as that characterizing 
sorted polygons. 
Depending on usage, synonymous terms 
may include fissure-polygons, mud-polygons, 
contractional polygons, and others. Ice-wedge 
polygons, tussock-birch-heath polygons, vege- 
tation polygons and desiccation polygons are 
special varieties of non-sorted polygons. The 
ice-wedge polygons are characterized by bor- 
dering ice wedges. Synonymous terms are 
tundra polygons and Taymyr polygons. 
Sorted steps are patterned ground with a step- 
like form and a sorted appearance due to a 
downslope border of stones embanking an 
area of finer material upslope. Non-sorted 
steps are patterned ground with a steplike 
form and a non-sorted appearance due to a 
downslope border of vegetation embanking 
an area of relatively bare ground upslope. 
Sorted stripes are patterned ground with a 
striped pattern and a sorted appearance due 
to parallel lines of stones and intervening 
strips of dominantly finer material oriented 
down the steepest available slope. Non-sorted 
stripes are patterned ground with a striped 
pattern and a non-sorted appearance due to 
parallel lines of vegetation-covered ground 
and intervening strips of relatively bare 
ground oriented down the steepest available 
slope. A synonymous term is solifluction 
stripes (Washburn). 
Britton's excellent paper on ‘Vegetation of 
the Arctic Tundra’ (1957), see references, also