1. The Moss peat banks of Signy & Moe Islands, South Orkney Islands
The peat is formed by two species of moss: Polytrichum strictum and Chorisodontium aciphyllum. It
is underlain by permafrost at a depth of c.15-20 cm, and is up to two metres thick and 5,000
Deep moss peat banks on level or gently sloping ground at the northwest end of the island.
Note that a metre rule is visible as a scale marker in some photos.
A turf on a steep slope dominated by Polytrichum strictum below Observation Bluff.
All pictures were taken while James was working for the British Antarctic Suvey in
the 1970s. Click here for more info. on Antarctic peat.
2. Vertical edges of Antarctic moss peat banks
A characteristic of many Antarctic moss peat banks is that one side has a vertical edge. These are visible in
many of the photographs above taken on the South Orkney Islands. However the tallest such edge, at 3m
height, is at Walker Point, Elephant Island (see picture below).
The vertical edges are not erosion features – note the absence of eroded peat at their base. The pictures
here demonstrate their formation. All the pictures were taken on Signy Island in 1975.
Picture 4 is a key one, showing how moss shoots at the edge of the moss bank break off and hang down.
This can happen at periodic intervals, as illustrated in picture 5. The whole structure is supported by the
permanently frozen undecomposed moss peat (permafrost).
For a description of how they form see: Fenton, J. 1982. The formation of vertical edges on Antarctic
moss peat banks. Arctic & Alpine Research Vol. 14.
3. Erosion of moss peat banks
Although the vertical edges are not erosion features, erosion can sometimes be observed on Antarctic
moss peat. This illustrates the point that peat erosion can ba a natural phenomenon, occurring in the
absence of grazing, burning or human impact.
These pictures all taken in 1975.
4. Ice retreat
These pictures show peat (black) which has been exposed as
permanent ice has retreated. This indicates that the climate
has varied over the years. All photos taken 1975. See the
paper: Fenton, J. 1982. Vegetation re-exposed after burial by
ice and its relationship to changing climate in the South
Orkney Islands. British Antarctic Survey Bulletin Vol. 51.
5. Other moss peat banks in Antarctica & South Georgia
1 & 2: Moss turf dominated by Chorisodontium aciphyllum at Shingle Cove,
Coronation Island (South Orkneys). Pictures taken 1999.
3-8: Moss turf dominated by Polytrichum strictum on steep ground above
the penguin colony on Cuverville Island (Antarctic Peninsula). Note that
the moss is slowly sliding downhill over the permafrost, with picture 8
showing moss peat which has slid down and accumulated at the bottom
of slope. Pictures taken 1988/9.
9: Moss turf dominated by Polytrichum strictum at Galindez Island,
Argentine Islands (Antarctic Peninsula). See also the two pictures of
Galindez Island under ‘Ice Retreat’ above. Pictures taken 1975.
10: The deepest moss peat bank found: c.3m deep, at Walker Point on
Elephant Island (picture from 1976-7 Joint Services Expedition).
11: Turf of Polytrichum strictum at Maiviken, on South Georgia, with the
grass Festuca contracta. Picture taken 1975.
A collapsed vertical edge: perhaps the underlying permafrost which holds the whole
bank together, has thawed. Signy Island.
The active layer (unfrozen moss & peat) has slid down over the permafrost
(permanently frozen peat). Moe Island.
3-7 Erosion of the surface of the peat bank, possibly caused by exposure to wind as the
peat has become deeper. Pictures 3-5 Signy Is, 6-7 Moe Island.
Wind has here blown away a section of
Antarctic-type peat formed by Polytrichum strictum has recently been found by the author
outside Antarctica in both the Falkland Islands and Scotland. See pictures below.
The surface 5cm of an Antarctic moss turf of Polytrichum strictum showing the tightly-bound
moss shoots. In this species the shoots are held together by rhizoids, small root-like outgrowth
similar to roots in higher plants. In this picture two-year’s growth of rhizoids are visible growing
out of the cut surface of the turf.
See also my paper:
The rate of peat accumulation in Antarctic moss banks
Journal of Ecology, 1980, Vol.68, No, 1, pp. 211-228
For a full description of this habitat see: James Fenton & Ron Lewis Smith, 1982. Distribution, composition
and general characteristics of the moss banks of the maritime Antarctic. British Antarctic Survey Bulletin
A dome of Polytrichum strictum peat recently found by the
author in the Falkland Islands.
A turf of Polytrichum strictum peat recently found by the
author on the island of Islay in Scotland.