PHOTOGRAMMETRIC ENGINEERING 
  
FiG. 11. Ground photo of mon-sorted polygons 
(ice-wedge polygons) in the continuous-perma- 
frost zone near Barrow, Arctic coastal plain of 
Alaska. Flat to high-centered polygons with shal- 
low troughs (upper center); 'Alaska Cotton" 
(Eriophorum Scheuchzeri), center; Mud cracks 
(foreground). (Photo by the author August 19, 
1 
J. 
deals with the conspicuous ground patterns 
on the Coastal Plain, the ice-wedge polygons. 
Depending especially on differences in distri- 
bution and permanency of standing waters 
and the distribution of vegetation types, the 
surface of the polygons may vary in many re- 
spects. According to the origin, growth and 
decay of the polygons, i.e. their gradational 
forms, the features will change from flat sur- 
face with cracks to low-centered polygons, 
and, finally, to high-centered polygons. Low- 
center polygons are characteristic of the wet- 
test terrain and high-center ones of the best 
drained slopes. Ridged polygons are ice-wedge 
polygons with low ridges around the margin 
of the polygon. 
In the Swedish Arctic region, especially on 
permanently frozen peat-bogs, there are 
dome-shaped hillocks generally 10-13 feet 
high (observed maximum 23 feet) composed 
of a core of massive ice or ice-impregnated 
peat covered by about 3 feet of insulating 
peat and moss species. They are called ““pal- 
sar" and may be compared with the Alaskan 
isolated, steep-sided, symmetrically rounded 
mounts or hillocks called pingos. These may 
attain a height of 10 to 100 feet or more, and 
are prominent features on the Arctic plain. 
DISTRIBUTION OF PATTERNED GROUND 
Patterned ground occurs not only in polar, 
subpolar, and alpine regions, but even in 
many other areas of the world, where climate 
and terrain favor frost action. A typical ex- 
ample of a more or less unexpected area of 
patterned ground is the low-leveled island 
Oland in the southern Baltic Sea at the east 
coast of Sweden. Oland is known for its silu- 
rian-ordovician limestone layers, its mild cli- 
mate in summer and fall but with relatively 
cold winters. There occur perfect developed 
patterned ground with sorted as well as non- 
sorted nets and polygons, well worth a care- 
ful study (Rydquist, 1957). Troll, too, see 
references, has described these features and 
shown some good photos from this fascinat- 
ing island in his well known work "'Struktur- 
bóden, Solifluktion und Frostklimate der 
Erde," 1944. Troll chose most of the pictures 
in this work from high alpine regions, e.g. 
Hohe Tauern at about 8,860 feet (2,700 m.) 
and Lechtal Alps at about 7,540 feet (2,300 m.), 
both in Austria, Jedigól, Ala Dag in Turkey 
(north of Cyprus) at 9,840 feet (3,300 m.), 
Ethiopia at 9,840-10,820 feet (3,000—3,300 
m.), Mount Kenya, East Africa, at abt. 
13,120-14,100 feet (4,000-4,300 m.), Drak- 
bergen (the Dragon Mountains), South Afri- 
ca, at 6,560—8,200 feet (2,000—2,500 m.) and 
10,160—10,500 feet (3,100—3,200 m.) and Cor- 
dillera Real, Bolivia, at about 15,740—16,730 
feet (4,800-5,100 m.). Further, there are 
striking photos from the Arctic, showing 
characteristic ground patterns in West Spits- 
bergen and Alaska, the Taymyr Peninsula, 
Central Siberia, and others. 
Washburn has chosen excellent photos of 
patterned ground for his above mentioned 
“Classification” from Alaska, Canada, East 
Greenland, West Spitsbergen, Northern and 
Middle Sweden (Dalecarlia), and Mendoza- 
Argentina (Cordillera de Los Andes). 
In his earlier paper on “Patterned Ground’ 
  
FrG. 12. Ground photo of mon-sorted polygons 
(ice-wedge polygons) in the continuous-perma- 
frost zone near Barrow, Arctic coastal plain, 
Alaska. High-centered, partly cracked, polygons 
(center), a great thaw lake in background. (Photo 
by the author August 19, 1955.) 
— 
Ur