Francelino Et Al., 2010

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Research Highlights

Catena xx (2011) xxx xxxGeomorphology and soils distribution under paraglacial conditions in anice-free area of Admiralty Bay, King George Island, Antarctica

Marcio Rocha Francelino a,, Carlos Ernesto R.G. Schaefer b, Felipe Nogueira Bello Simas b, Elpdio Incio Fernandes Filho b,Jos Joo Lelis Leal de Souza b, Liovando Marciano da Costa b

a Departamento de Silvicultura, Universidade Federal Rural do Rio de Janeiro, BR 465 km 7 Seropedica, RJ, Brazilb Departamento de Solos, Universidade Federal de Viosa; AV PH Rolfs s/n Viosa, MG, Brazil

1314 Periglacial and paraglacial geomorphology of Antarctica. Weathering and soil formation of polar regions. Cryosols and active layer in Antarctica;15sulfate-affected soils of Antarctica. Landscape evolution and climate change in Antarctica. Soils and landform relationships in polar regions.

Catena xxx (2011) xxx

0341-8162/$ see front matter 2010 Published by Elsevier B.V.

doi:10.1016/j.catena.2010.12.007

Contents lists available at ScienceDirect

Catena

j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / c a t e n a

Please cite this article as: Francelino, M.R., et al., Geomorphology and soils distribution under paraglacial conditions in an ice-free area ofAdmiralty Bay, King George Island, Antarctica, Catena (2011), doi:10.1016/j.catena.2010.12.007

CATENA-01586; No of Page 1
http://dx.doi.org/10.1016/j.catena.2010.12.007http://www.sciencedirect.com/science/journal/03418162http://dx.doi.org/10.1016/j.catena.2010.12.007http://dx.doi.org/10.1016/j.catena.2010.12.007http://www.sciencedirect.com/science/journal/03418162http://dx.doi.org/10.1016/j.catena.2010.12.007


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1 Geomorphology and soils distribution under paraglacial conditions in an ice-free area2 of Admiralty Bay, King George Island, Antarctica

3 Marcio Rocha Francelino a,, Carlos Ernesto R.G. Schaefer b, Felipe Nogueira Bello Simas b,4 Elpdio Incio Fernandes Filho b, Jos Joo Lelis Leal de Souza b, Liovando Marciano da Costa b

5a Departamento de Silvicultura, Universidade Federal Rural do Rio de Janeiro, BR 465 km 7 Seropedica, RJ, Brazil

6b Departamento de Solos, Universidade Federal de Viosa; AV PH Rolfs s/n Viosa, MG, Brazil

7

8

a b s t r a c ta r t i c l e i n f o

910 Available online xxxx

111213

14 Keywords:

15 Cryosols

16 Permafrost

17 Terrestrial ecosystem

18 Periglacial

19The main pedological, geomorphological and cryogenic features of Keller Peninsula, part of Admiralty Bay,

20King George Island, Maritime Antarctica, were mapped and quantified with emphasis on the relationship

21between the ice retreat process, melt-out, landform development and soil distribution. Moraines, protalus,

22scree slopes, inactive glacial cirques, uplift marine terraces, biogenic landforms, artes and Felsenmeer were

23mapped. Scree-slopes are the main landform, covering approximately 25% of the peninsula, indicating

24prominent paraglacial features. Inherited, glacial landform, such as lateral moraines, highland plateau and25exhumed U shaped-valleys, is now being exposed in north Keller by ice shrinkage of former ice protecting

26cover. Landforms influenced soil formation and stability. Cryosols and Leptosols (WRB) roughly

27corresponding to Gelisols and Entisols (SSS), respectively, are the most common soil classes, with an overall

28tendency of no permafrost in the coastal areas, grading to sporadic permafrost at mid-slope, and

29discontinuous permafrost with greater altitude and stability.

30 2010 Published by Elsevier B.V.

3132

33

34

35 1. Introduction

36 The landscape of ice-free areas of Maritime Antarctica results from

37 a recent ice retreat phase in a cold and relatively wet environment, in

38 which freezing and thawing processes are the primary mechanisms,

39 although some features can be inherited from previous cycles ( Andr,

40 2003). Hence, frost shattering and the myriad of relatedprocesses (for

41 example cryoplanation, nivation, and ablation) are locally enhanced,

42 due to a very rapid increase in average temperatures in this part of

43 Antarctica during the last decade.

44 Previous studies in the South Shetland Islands conclude that these

45 were affected by two Pleistocene glaciations (John and Sudgen, 1971).

46 During the climax of the Quaternary glaciations, there was a single,

47 continuous ice-sheet linking all South Shetlands. During the last

48 glaciation, each Island developed its own ice-sheet which covered

49 most present-day ice-free areas (Palls et al., 1995).

50 Frequent freeze-and-thaw is the main factor in rock disintegration

51 in cold regions (Boelhouwers et al., 2003). The manifestation of

52 physical weathering in Maritime Antarctica is extreme due mainly to

53 relatively high moisture availability (Schaefer et al., 2004).

54 Detailed data on pedo-geomorphology of Antarctica is largely

55 restricted to frigid areas, especially from south Victoria Land. There is

56some detailed information on sub-Antarctic soils and landforms

57referring to Marion Island and South Georgia (Boelhouwers et al.,

582000). According to Walton (1984) there is a need for integrated

59biological, pedological and geomorphological studies in the Antarctic

60Peninsula, not yet fulfilled to this day. This requires the interpretation

61of biological data combined with edaphic and geomorphological

62studies to fill the gap in integrated knowledge of Maritime Antarctica

63landscapes.

64The objective of the present work is to describe and map the main

65landforms and cryogenic features of Keller Peninsula, King George

66Island in 1:5000 scale and study the relationship between landscape

67and soil formation in this part of Maritime Antarctica.

682. Material and methods

692.1. Study area

70Keller Peninsula is located in Admiralty Bay, King George Island

71(Fig. 1), between the Martel and MacKellar Inlets. It covers

72approximately 500 ha, with a northsouth length of 4 km and less

73than 2 km in width. Mean annual air temperature is 1.8 C and

74precipitation averages 360 mm/year (Table 1). Climate is typical of

75Maritime Antarctica, but somewhat warmer due to the Peninsula's

76inner position in Admiralty Bay (Rakusa-Suszczewski et al., 1993;

77Tricart, 1973).

Catena xxx (2011) xxxxxx

Corresponding author.

E-mail address: [email protected] (M.R. Francelino).

CATENA-01586; No of Pages 11

0341-8162/$ see front matter 2010 Published by Elsevier B.V.

doi:10.1016/j.catena.2010.12.007

Contents lists available at ScienceDirect

Catena

j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / c a t e n a

http://dx.doi.org/10.1016/j.catena.2010.12.007http://dx.doi.org/10.1016/j.catena.2010.12.007http://dx.doi.org/10.1016/j.catena.2010.12.007mailto:[email protected]://dx.doi.org/10.1016/j.catena.2010.12.007http://www.sciencedirect.com/science/journal/03418162http://dx.doi.org/10.1016/j.catena.2010.12.007http://dx.doi.org/10.1016/j.catena.2010.12.007http://www.sciencedirect.com/science/journal/03418162http://dx.doi.org/10.1016/j.catena.2010.12.007mailto:[email protected]://dx.doi.org/10.1016/j.catena.2010.12.007


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The relief ranges from 0 to 340 meters above sea level (masl). Thesubstrates are Late Tertiary volcanic rocks, ranging from tholeithicbasalts to andesites, forming part of the Andeanpeninsular

Antarctica orogenic belt (Binkenmajer, 2001). In parts of KellerPeninsula, outcrops of sulfide-bearing andesites give origin to acid-sulfate sediments and soils (Simas et al., 2006), which contrast withthe surrounding basaltic materials for its yellowish color, easily

distinguishable in the field and through remote sensing.

86The absence of any glacial outlet coming from inland areas of

87Keller Peninsula hinterland indicates that most glacially derived

88till and related deposits are inherited from previous cycles of

89melt-out. The volcanic rock regolith of Keller Peninsula is

90subjected to a number of cryogenic processes leading to physical

91breakdown, sorting and increase in fine-particles. The most

92important factors are freezingthawing cycles, ablation, frost

93and solifluction.

Fig. 1. Location of Keller Peninsula in Admiralty Bay, King George Island, Maritime Antarctica with the produced photomosaic.

Table 1

Climatic data at Keller Peninsula between 1986 and 2003 (INPE/CPTEC, 2003).

Month Air temperature (C) Barometric pressure (mbar) Wind speed Precipitation Relative humidity

(%)Mean Min. Max. Mean Min. Max. m/s mm

Jan. 2.2 5.2 14.0 989.5 952.7 1017.2 5.3 34.4 86.6Feb. 2.3 7.0 10.7 989.9 953.9 1019.3 5.3 38.1 85.7

Mar. 1.1 10.2 10.3 991.0 947.7 1027.5 5.8 44.2 86.0

Apr. 1.3 17.0 10.9 991.2 959.1 1024.1 5.7 43.4 86.2May 3.3 23.5 7.5 993.4 958.9 1033.5 5.3 25.2 84.0

0 Jun. 5.8 25.0 7.3 993.4 954.1 1030.9 6.3 21.7 84.8

1 Jul. 6.4 27.7 6.3 992.4 953.0 1033.5 6.4 21.7 84.8

2 Aug. 5.1 14.7 0.8 990.5 950.0 1024.7 6.6 22.3 86.23 Sep. 4.1 21.1 7.7 991.9 950.0 1037.4 6.6 23.0 85.74 Oct. 2.2 16.1 7.1 987.1 943.8 1021.6 6.5 21.6 83.75 Nov. 0.0 12.0 14.4 986.0 951.1 1020.5 5.9 42.8 84.26 Dec. 1.3 5.1 12.0 987.4 959.4 1019.2 5.4 28.3 84.17 Annual 1.8 27.7 14.4 990.3 943.8 1037.4 5.9 366.7 85.2

2 M.R. Francelino et al. / Catena xxx (2011) xxxxxx

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94 2.2. Geomorphological mapping

95 Landforms described in this work were investigated both at field

96 scale and through detailed mapping from photo interpretation of high

97 quality aerial photographs obtained in the summer of 2002/2003, at

98 1:5000 scale. Photographs were obtained by adapting a metric

99 Hasselblad camera set in a temperature-controlled system coupled

100 under the helicopter cabin. A mosaic of 24 photographs was produced

101

using the PanaVue Assemble 2.10 software. The mosaic was102 georeferenced using control points obtained in the field using a

103 Promark II DGPS. The resulting map was verified and adjusted in the

104 following summer (2003/2004).

105 Stereoscopic photointerpretation was carried out, using the

106 central part of the stereoscopical pair. The geomorphological features

107 were drawn on acetate peels and digitalized on a digitizer table using

108 the ArcInfo software. In situ systematic observations on surface

109pattern, depth and distribution of soils, permafrost and landscape

110features were carried out between December 2002 and March 2003.

1112.3. Soil characterization

112In total, 26 soil pits were described. Soil classification followed the

113World Reference Base for Soil Resources (WRB) classification system

114(IUSS Working Group WRB, 2006) and then correlated with the US

115

Soil Taxonomy (SSS, 2010).116Soil samples were collected, air dried, passed through a 2 mm

117sieve and submitted to chemical and physical analyses. Soil pH,

118exchangeable nutrients and texture were determined according to

119EMBRAPA, 1997. Exchangeable Ca2+, Mg2+ and Al3+ were extracted

120with 1 mol L1 KCl and P, Na and K with Mehlich1 extractant

121(dilute double 0.05 mol L 1 HCl in 0.0125 mol L 1 H2SO4)

122(EMBRAPA, 1997). Nutrient levels in the extracts were determined

Fig. 2. Geomorphological map of Keller, interpreted from aerial photographs taken in 2002/03.

3M.R. Francelino et al. / Catena xxx (2011) xxxxxx



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by atomic absorption spectrometry (Ca2+, Mg2+ and Al3+), flameemission (K and Na) and photocolorimetry (P). Total organic C wasdetermined on samples ground to b0.5 mm by wet combustion

(Yeomans and Bremer, 1998). The remaining P (Prem) was obtainedafter shaking a CaCl2 10 mmol L

1 solution containing of 60 mg L1

ofP with5 g ofsoil for 1 h. The P remaining in solution gives an idea ofthe P adsorption capacity of the sample.

Total nitrogen was determined by the Kjeldahl method(EMBRAPA, 1997). Soil texture was analyzed by mechanical disper-sion of b2 mm air-dried samples in distilled water, sieving andweighing of coarse and fine sand, sedimentation of the silt fractionfollowed by siphoning of the b2 m fraction (Gee and Bauder, 1986).

3. Results and discussion

3.1. Landforms and processes: general features

Eighteen geomorphological units were identified and mapped inKeller Peninsula (Fig. 2, Table 2). The snow banks were classified as a

separate unit, as it was virtually impossible to infer the underlyingfeatures. Scree slopes are the predominant landform occupyingapproximately 25% of the ice-free area, followed by talus slopes(10.7%), indicating the active periglacial erosion in this mountainous

area.Overall, the landforms of Keller can be described as paraglacial,

due to the recent exposure of formerly glaciated terrains (French,1996). However, southern Keller Peninsula shows an older and more

stable landscape due to earlier exposure following glacial retreat.Hence, rounded and gentle forms are observed, with extensive

149solifluction lobes in the eastern face due to widespread ablation of

150glacial cirques from upland sources. In general, solifluction is the

151dominant erosion process in Keller, highlighting its active periglacial

152condition.

153The centralpart of the peninsulais formed by artes divides, which

154terminate in the south with two small plateaux Tyrrell and Flagstaff

155(Morro da Cruz) (Fig. 3). To the north, the peninsula is bordered by

156the Birkenmajer Peak, with 340 masl, followed by glaciers. In the

157eastern, more sloping face, glacial cirques andother activefeatures are

158present.

1593.2. Soil classification and distribution

160Soils of Keller Peninsula are generally shallow, often presenting

161lithic or paralithic contact within the first meter. Another common

162feature is the very high gravel content, resulting in a skeletic

163character. Soils are poorly developed and show evidences of strong164cryoclastic weathering and cryoturbation. For all profiles, soil

165morphology and chemistry is closely related to the parent material

166(Simas et al., 2008). Due to the active periglacial erosion, with a

167marked influence of solifluction, the regoliths are generally very

168shallow and unstable, with steep slopes. Thus, only 49.5% of Keller

169Peninsula is sufficiently stable to allow greater soil development, and

170the remaining 50.5% is composed by rock outcrops or unstable, steep

171areas (Table 2). Vegetation cover occurs on less than 3% of the total

172area.

173Nine soil complexes were identified and mapped (Table 2).

174Cryosols and Leptosols (IUSS, 2006), corresponding roughly to

175Gelisols and Entisols of the US Soil Taxonomy (SSS, 2010),

Fig. 3. View of the east face of Keller Peninsula: Moraine field (1); The FlagstaffMorro da Cruz plateau (2); Tyrrell plateau and its downslope protalus rampart (3); the Noble and

Babylon rock glaciers and; (4) Birkenmajer Peak.

Table 2

Landform types and corresponding soil mapping unit (WRB systems) and their total area and relative contribution in Keller Peninsula.

Landforms Soil complexes Area

WRB ha %

Rock outcrops Lithic Leptosol (Eutric, Ornithic) +Turbic Cryosol (Eutric) 32.6 6.4

Circles 30.5 6.0

Ice walls 1.2 0.2

Rock crest Lithic Leptosol (Eutric, Ornithic) +Turbic Cryosol (Eutric) 33.1 6.5

Felsenmeer Turbic Cryosol (Eutric, Ornithic) + Turbic Cryosol (Thionic) + Lithic Leptosol (Ornithic) 28.1 5.60 Glaciers 55.8 11.01 Moraines Turbic Cryosol (Eutric)+Turbic Cryosol (Thionic)+Andic Cambisol (Eutric, Skeletic, Gelic, Thionic,and Ornithic) 12.0 2.42 Snow banks 63.1 12.53 Outwash plains Stagnic Fluvisol (Gelic) +Stagnic Fluvisol (Thionic) 6.8 1.34 Plateaux Turbic Cryosol (Eutric) +Andic Cambisol (Eutric) 6.3 1.2

5 Beach 6.6. 1.3

6 Protalus ramparta Turbic Cryosol (Eutric) +Andic Leptosol (Gelic, Ornithic) 27.3 5.4

7 Scree slope 127.0 25.1

8 Talus 54.7 10.8

9 Marine terraces Haplic Regosol (Gelic) + Andic Cambisol (Skaletic, Gelic) + Andic Cambisol (Thionic) 21.2 4.20 Total area 506.2 100

a Protalus rampart: the term was defined by Whalley and Azizi (2003), : units without soils.1




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Table 33:1

Chemical analyses of selected soil profiles in Keller Peninsula.

3:2

3:3 Depth pH (H2O) P K Na Ca Mg Al H+Al BS t Total CEC V ISNa Prem TOC

3:4 (mg kg1) (cmolc dm3) (%) mg L 1 dag kg1

3:5 Cryosols paralithic profile 02

3:6 010 7.8 197 122 248 15 13 0.0 1.5 29.4 29.4 30.9 95.0 3.7 33.0 0.23:7 1020 7.8 105 138 204 20 11 0.0 1.3 32.2 32.2 33.5 96.0 2.8 30.0 0.23:8 2030 7.6 35 134 276 21 9 0.0 1.0 31.5 31.5 32.5 97.0 3.8 30.0 0.23:9 3040 7.8 89 140 314 27 10 0.0 0.0 38.7 38.7 38.7 100.0 3.5 36.0 0.13:10 4050 7.9 142 102 196 31 11 0.0 0.0 43.1 43.1 43.1 100.0 2.0 42.0 0.13:11 5060 8.0 148 104 183 30 10 0.0 0.0 41.1 41.1 41.1 100.0 1.9 43.0 3:12

3:13 Cambisols skeletic profile 6

3:14 010 0.5

3:15 1020 8.0 255 70 218 27 7 0.0 0.3 35.1 35.1 35.4 99.0 2.7 47.0 0.2

3:16 030 7.9 149 56 230 17 4 0.0 0.0 22.1 22.1 22.1 100.0 4.5 47.0 0.1

3:17

3:18 Cryosols skeletic profile 10

3:19 010 6.5 72 64 135 10 2 0.0 1.3 12.8 12.8 14.1 91.0 4.7 40.0 2.93:20 1020 6.7 86 46 90 9 2 0.0 1.2 11.5 11.5 12.7 91.0 3.4 38.0 0.93:21

3:22 Leptosols ornithogenicgelic profile 11

3:23 010 6.0 50 108 200 11 11 0.7 8.7 23.1 23.8 31.8 73.0 3.7 28.0 3.23:24 1020 6.3 207 101 188 16 16 0.3 4.1 33.1 33.4 37.2 89.0 2.5 34.0 0.8

3:25 2030 6.5 250 108 202 16 16 0.1 0.0 33.2 33.3 33.2 100.0 2.6 33.0 0.53:26

3:

27 Cryosols vitric

leptic

profile 173:28 010 7.7 313 47 140 47 6 0.0 0.8 53.7 53.7 54.5 99.0 1.1 36.0 0.1

3:29 1020 7.6 423 38 115 64 5 0.0 1.0 69.6 69.6 70.6 99.0 0.7 39.0 0.2

3:30 2030 7.8 397 34 105 69 4 0.0 0.5 73.5 73.5 74.0 99.0 0.6 41.0 0.13:31 3040 7.9 254 31 82 59 3 0.0 0.7 62.4 62.4 63.1 99.0 0.6 46.0 0.23:32 4050 6.2 271 51 83 57 3 0.0 2.6 60.5 60.5 63.1 96.0 0.6 43.0 0.13:33 5060 7.3 318 54 81 62 3 0.0 1.8 65.5 65.5 67.3 97.0 0.5 42.0 0.13:34

3:35 Leptosols ornithogenicgelic profile 18

3:36 010 5.8 308 125 204 19 9 0.3 4.8 29.2 29.5 34.0 86.0 3.1 38.0 0.93:37 1020 6.4 417 158 198 24 10 0.0 3.6 35.3 35.3 38.9 91.0 2.5 36.0 0.4

3:38 2030 6.8 393 133 168 24 8 0.0 3.3 33.1 33.1 36.4 91.0 2.2 39.0 0.3

3:39 3040 7.1 354 153 194 28 7 0.0 3.0 36.2 36.2 39.2 95.0 2.4 41.0 0.2

3:40 4050 7.3 324 144 180 29 5 0.0 1.5 35.2 35.2 36.7 96.0 2.2 38.0 0.2

3:41 5060 7.3 338 106 131 26 4 0.0 11.1 30.8 30.8 41.9 73.0 1.9 43.0 0.2

3:42

3:43 Cryosols skeletic profile 19

3:

44 0

10 5.4 13 109 122 9 9 0.1 14.4 18.8 18.9 33.2 56.0 2.9 12.0 2.53:45 1020 5.3 14 101 122 9 10 1.7 1.5 19.8 21.5 21.3 93.0 2.5 9.0 2.23:46 2030 5.6 25 116 128 12 13 0.5 10.6 25.9 26.4 36.5 71.0 2.1 10.0 1.83:47

3:48 Regosol paraliticgelic profile 20

3:49 010 5.0 190 145 206 6 3 1.1 11.4 10.3 11.4 21.7 49.0 7.5 33.0 6.53:50 1020 5.5 128 95 210 9 5 0.3 6.3 15.2 15.5 21.5 70.0 6.1 33.0 1.9

3:51 2030 5.9 65 110 212 9 5 0.1 4.3 15.2 15.3 19.5 77.0 6.3 30.0 0.7

3:52 3040 6.6 65 132 214 10 5 0.1 2.0 16.3 16.4 18.3 89.0 5.6 30.0 0.6

3:53 4050 6.8 261 165 200 11 5 0.1 1.0 17.3 17.4 18.3 94.0 5.1 32.0 0.53:54 5060 7.2 398 172 190 16 7 0.0 1.7 24.3 24.3 26.0 93.0 3.5 34.0 0.33:55

3:56 Regosol skeleticgelic profile 21

3:57 010 6.7 308 72 200 16 7 0.0 1.8 24.1 24.1 25.9 93.0 3.7 47.0 0.93:58 1020 6.5 135 67 190 6 3 0.0 1.7 10.0 10.0 11.7 86.0 8.1 47.0 0.23:59 2030 6.2 133 65 188 5 3 0.0 1.5 9.0 9.0 10.5 85.0 10.0 47.0 0.23:60 3040 6.3 133 64 214 5 3 0.0 1.3 9.1 9.1 10.4 88.0 10.3 42.0 0.2

3:61 4050 6.4 143 75 248 5 3 0.0 1.3 9.3 9.3 10.6 87.0 12.8 44.0 0.1

3:62

3:63 Cryosols lithic profile 24

3:64 010 5.1 45 74 166 20 10 7.6 12.0 30.9 38.5 42.9 72.0 1.9 12.0 0.5

3:65 1020 5.0 28 42 125 18 9 15.0 20.1 27.7 42.7 47.8 57.0 1.3 3.0 0.2

3:66 2030 4.7 21 25 84 17 5 27.0 31.0 22.4 49.4 53.4 42.0 0.7 1.0 0.13:67 3040 4.4 21 15 60 11 3 31.0 37.0 14.3 45.3 51.3 27.0 0.6 1.0 0.13:68 4050 4.3 19 18 55 6 1 33.0 38.0 7.3 40.3 45.3 16.0 0.6 1.0 0.13:69 5060 4.3 18 15 58 4 1 32.0 37.9 5.3 37.3 43.2 12.0 0.7 1.0 0.13:70

3:71 Fluvisols gelistagnic profile 25

3:72 010 4.5 76 42 75 5 0 36.0 42.7 5.4 41.4 48.1 12.0 0.8 0.0 0.43:73 1020 4.7 78 46 88 9 2 7.0 11.6 11.5 18.5 23.1 50.0 2.1 1.0 0.3

3:74 2030 4.8 96 45 96 10 2 4.0 8.3 12.5 16.5 20.8 60.0 2.5 3.0 0.3

BS: Bases Sum; V: Base saturation percentage; t: Effective Cation Exchange Capacity (CEC); TOC: Total Organic Carbon; Prem: remaining P.3:75




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respectively, are the most common soil groups but Cambisols,

Regosols and Fluvisols (IUSS, 2006) are also present, corresponding

to the Inceptisols, Orthents/Psamments and Fluvents (SSS, 2010). The

179distributionof these groups in the landscape is majorly determined by

180the presence or absence of permafrost, which defines the cryic

181horizon and is diagnostic of the Cryosol group (IUSS, 2006).

182In the present soil survey, we found at some sites frozen ground

183layers and water-logging with depth, indicating the proximity of the

184permafrost table, acting as a water impermeable layer. However, as

185this survey was carried out during only one season, it is not possible to

186affirm where permafrost in fact occurs. To do so, a two year

187

temperature monitoring would be necessary since the cryic horizon188is defined as a layer, thicker than 5 cm, which remains below 0 C for

189two consecutive years (IUSS, 2006). Nevertheless, our field observa-

190tions are in agreement with the general permafrost distribution

191model proposed for this region (Vieira et al., 2010). According to this

192model, permafrost is absent at the lowest portion of the landscape,

193sporadic at intermediate altitude and discontinuous at the uppermost

194part of the landscape.

195Due to the strong evidences of cryoturbation such as frost heave,

196sorting, thermal cracking and patterned ground, all Cryosols at Keller

197are best classified as Turbic Cryosols (Turbels according to the US Soil

198Taxonomy), with the cryic horizon starting within 200 cm of the soil

199surface. Turbic Cryosols form complexes with non-Cryosols, mainly

200Cambisols and Leptosols along the slopes and moraines. At the

201uppermost areas, Turbic Cryosols are expected to cover most of the

202areas, with Cambisols and Leptosols occurring as inclusions wherever

203permafrost is absent. As detailed later in the present paper, a large

204part of Keller Peninsula is covered with sulfate-affected sediment

205(Simas et al., 2006) which is spread over several different geomor-

206phologic environments. The Thionic suffix is used to differentiate

207these soils from the predominant basaltic and andesitic materials. It is

208noteworthy that such qualifier is not listed for the Cryosol soil group

209within the WRB (IUSS, 2006). Therefore, we propose its inclusion in

210this classification system. In the US Soil Taxonomy, although the

211sulfuric qualifier is listed for Gelisols, it is only used for soils with

212Aquic conditions during normal years (Aquiturbels and Aquorthels;

213SSS, 2010) which is not the case of most acid-sulfate soils found in

214Keller Peninsula which show good drainage conditions. Therefore, we

215propose the creation of the Sulfuric Haploturbel subgroup for

216classification of such soils within the US Soil Taxonomy.

2173.3. Landforms and soils

2183.3.1. Beaches

219Beaches in Keller Peninsula represent approximately 1.3% (6.6 ha)

220of the ice-free terrain (Table 2) and are composed mainly of gravels

221and shingles mixed with varying amounts of coarse sand by materials

222from upland screes and moraines. The marine erosion is active for 6

2237 months/year, with high erosive power (Araya and Herv, 1972a).

224The combined actions of small icebergs and waves lead to

225rearrangement of pebbles and shingle forming polygonal patterned

226ground, particularly in flat beaches, observed between Punta Plaza

227and Ferraz Station. These polygonal patterns are similar to sorted

228beach sediments described by Araya and Herv (1972b). Some are229covered by crustose lichens, green algae and cyanobacteria, indicating

230greater stability. No soil development is observed in present day

231beaches.

2323.3.2. Outwash plains

233Along the coastline, drainage channels running down from the

234snow-melting upslope tend to form large, coast-parallel, braided

235channels, leading to lakes, sedimentary depressions or eventually

236breaking through the marine terraces into the sea, with rapid

237periglacial erosion. A number of these channels and intermittent

238small-scale fluvio-glacial estuaries form during the early thawing in

239December, following previous drainage lines. Most catchments have a

240nival regime, characterized by maximum discharge in the summer,

241followingthe melting of the snow cover. The development of channels

Table 4

Physical analyses of selected soil profiles in Keller Peninsula.

Profile S an d

thick

Sand

fine

Silt Clay Silt/

clay

Gravel Texture Soil

color

(%)

(%)

Turbic Cryosol (Eutric) Pedon 02

010 34 14 31 21 1.5 57 Loam 2.5Y 5/1

1020 34 20 28 18 1.6 n.d. Sandy loam 2.5Y 5/2

2030 36 22 25 17 1.5 n.d. Sandy loam 2.5Y 5/2

3040 30 14 37 19 1.9 47 Loam 2.5Y 5/20 4050 36 21 20 23 0.9 n.d. Sandy clay loam 2.5Y 6/31

2 AndicCambisol (Skeletic) Pedon 6

3 010 51 3 22 24 0.9 79 Sandy clay loam 2.5Y 4/2

4 1020 41 7 24 28 0.9 n.d. Sandy clay loam 10YR 6/1

5 2030 58 6 16 20 0.8 53 Sandy loam 2.5Y 5/1

6

7 Lithic Leptosol (Gelic) Pedon 10

8 010 51 9 20 20 1.0 50 Sandy loam 2.5Y 5/29 1020 50 7 23 20 1.2 65 Sandy loam 2.5Y 5/20

1 Lithic Leptosol (Gelic, Ornithic) Pedon 11

2 1020 23 12 35 30 1.2 n.d. Clay loam 10YR 5/33 2030 27 7 35 31 1.1 44 Clay loam 10YR 5/3

4

5 Turbic Cryosol (Eutric) Pedon 17

6 010 24 3 42 31 1.4 42 Clay loam 2.5Y 5/37 1020 23 3 43 31 1.4 n.d. Clay loam 2.5Y6/3

8 2030 29 2 35 34 1.0 n.d. Clay loam 2.5Y 6/39 3040 19 4 48 29 1.7 59 Clay loam 2.5Y 6/20 4050 28 2 38 32 1.2 n.d. Clay loam 2.5Y 6/21 5060 31 4 30 35 0.9 n.d. Clay loam 2.5Y 6/22

3 Cambic Leptosol (Gelic, Ornithic) Pedon 18

4 010 29 8 33 30 1.1 33 Clay loam 5Y 5/15 1020 25 11 37 27 1.4 n.d Clay loam 2.5Y 6/16 2030 27 6 36 31 1.2 n.d Clay loam 5Y 5/1

7 3040 30 7 33 30 1.1 64 Clay loam 2.5Y 6/1

8 4050 31 6 35 28 1.3 n.d Clay loam 2.5Y 6/1

9 5060 30 6 35 29 1.2 n.d Clay loam 5Y 6/1

0

1 Turbic Cryosols (Thionic) Pedon 19

2 010 36 22 25 17 1.5 9 Sandy loam 10YR 5/4

3 10

20 36 20 26 18 1.4 24 Sandy loam 10YR 5/44 2030 35 15 33 17 1.9 58 Loam 2.5Y 6/65

6 Turbic Cryosol (Skeletic) Pedon 20

7 010 40 21 27 12 2.3 n.d. Sandy loam 10YR 4/38 1020 37 20 32 11 2.9 n.d. Sandy loam 10YR 5/69 2030 37 18 35 10 3.5 51 Sandy loam 10YR 5/6

0 3040 35 21 34 10 3.4 n.d. Sandy loam 10YR 5/4

1 4050 41 13 29 17 1.7 n.d. Sandy loam 2.5Y 6/4

2 5060 33 13 30 24 1.3 n.d. Franco 2.5Y 6/33

4 Haplic Regosol (Gelic) Pedon 21

5 010 83 6 6 5 1.2 55 Sandy 10YR 4/36 1020 89 4 4 3 1.3 n.d. Sandy 10YR 4/37 2030 87 5 4 4 1.0 n.d. Sandy 10YR 4/38 3040 87 4 5 4 1.3 33 Sandy 10YR 4/39 4050 88 4 4 4 1.0 n.d. Sandy 10YR 4/3

0

1 Turbic Cryosol (Thionic)

2 010 52 6 26 16 1.6 58 Sandy loam 2.5Y 5/4

3 1020 39 7 53 1 53.0 n.d. Silt loam 2.5Y 6/4

4 2030 26 10 63 1 63.0 n.d. Silt loam 2.5Y 7/6

5 3040 28 6 65 1 65.0 38 Silt loam 2.5Y 7/66 4050 25 7 66 2 33.0 n.d. Silt loam 2.5Y 7/67 5060 28 6 65 1 65.0 n.d. Silt loam 2.5Y 7/68

9 Stangnic Fluvisol (Gelic, Thionic)

0 010 37 12 49 2 24.5 52 Sandy loam 2.5Y 6/41 2030 76 2 20 2 10.0 68 Sandy loam 2.5Y 6/4

n.d. not determined.2




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242 is particularly frequent in the western part of the Peninsula, where

243 slopes are gentle. We have interpreted these channels as fluvio-glacial

244 fans of periglacial origin.

245 These features represent approximately 1.3% of Keller Peninsula

246 and are commonly colonized with moss carpets and cyanobacterial

247 mats, due to widespread inundation. Soils are classified as Stagnic

248 Fluvisol (Gelic, Thionic) by the WRB (Tables 3 and 4, profile 25). This

249 soil represents an area affected by sulfates derived from sulfide-

250

bearing andesites. For this reason low pH values were observed (pH251 ranging from 4.5 to 4.8) and very low Ca2+ and Mg2+ when compared

252 to soils derived from basaltic and andesitic rocks (pedons 2, 6, 10, 11,

253 17, and 18). The extremely high exchangeable aluminium (Al3+) and

254 very low Prem indicate the presence of poorly crystalline Al and Fe

255 minerals as described by Simas et al. (2006) for similar soils from

256 Keller Peninsula. Soils are skeletic with over 65% of gravel in

257 subsurface. Oxidized iron stains on rocks and pebbles are commonly

258 observed in these environments, evidencing iron migration and

259 precipitation, attesting the occurrence of chemical weathering in

260 these paraglacial systems despite the extremely low temperatures.

261 3.3.3. Marine terraces

262 Three levels of uplifted marine terraces occur in Keller Peninsula,

263 representing 4.2% of the total ice-free area. They are formed by264 rounded gravels and shingles of different sizes and lithologies ranging

265 from one up to 19 masl near Punta Plaza, on the southernmost part of

266 Keller Peninsula. Marine terraces are the preferred nesting sites of

267 many Antarctic birds, thus creating favorable microenvironments for

268 plant colonization and diversification. These terraces are the primary

269 areas of carbon sink and enhanced bioavailability of nutrients in

270 coastal environments (Schaefer et al., 2004).

271 There is an apparent synchrony between the Holocene deglacia-

272 tion and the uplift of marine terraces in Keller, attributed to isostatic

273 rebound in the earliest exposed south part. This is consistent with

274 observation from elsewhere in theSouth ShetlandsIslands by Palls et

275 al. (1995) and Araya and Herv (1972c). Radiocarbon dating of

276 various marine terraces in this part of the Antarctic, reviewed by

277

Clapperton and Sugden (1988) indicates the oldest Holocene terrace278 with 6.000 y.b.p. The uplifted marine terraces and tabular landforms

279 appear to be associated with neotectonic formative processes,

280 developing a typical step-like topography of south Keller Peninsula.

281 Terraces have gentle to flat relief, where seasonal summer

282 waterlogging occurs, allowing cyanobacterial and mosses to form

283 plant communities on silty sediments. Buried moss tufts are

284 occasionally observed, indicating renewed upslope periglacial erosion

285 and solifluction. In the eastern slope, marine terraces are most

286 affected by active solifluction. According to the current permafrost

287 distribution model for this part of the globe, permafrost is absent at

288 this part of the landscape. Cambisols and Regosols are the dominant

289 soil groups. Pedon 6, classified as Andic Cambisol (Skeletic),

290 represents this environment. Soil pH is close to 8.0 as expected for

291 soils developed from basalts andandesites in this region, as well as the

292 relatively high exchangeable Ca and Mg (Table 3). It has over 70% of

293 gravel in surface and 50% in subsurface and close to 50% of sand at all

294 horizons, attesting its skeletic nature (Table 4).

295 3.3.4. Moraines

296 Contrasting with other ice-free areas of Admiralty Bay, Keller has

297 very limited moraines, representing only 2.4% of the total area. These

298 moraines were not formed by the present small glaciers coming from

299 upland cirques, but are wasted relicts of the progressive advance/

300 retreat of north/south ice lobes comingfrom the north duringpeaks of

301 Pleistocene glaciations (Clapperton and Sugden, 1988), being inher-

302 ited glacial landforms. Some are weathered and stabilized, and all

303 show evidence of periglacial erosion following exposure, consistent

304 with the observation ofPalls et al. (1995) in the Livingstone Island.

305Moraines are concentrated in South Keller Peninsula, where the

306terminal types are the commonest. The presence of allochthonous

307erratics in the moraine located at the foot of Flagstaff Plateauindicates

308long-distance transport from the former glacial dome to the north.

309Permafrost is regarded as sporadic at this part of the landscape and

310therefore the soils of moraines are best described as a complex of

311Turbic Cryosols and Andic Cambisols is present. Some moraines are

312formed from sulfate-affected materials, originating Thionic soils. In

313

other cases, localized bird activity results in the Ornithic character.314Pedon 2, Turbic Cryosol (Eutric) represents moraine formed from

315basaltic and andesitic materials without influence of sulfates. High

316values of soil pH, extractable P and exchangeable Ca and Mg are

317consistent with substrate geochemistry. The value of Cation Exchange

318Capacity at pH 7.0 is very close to that obtained at soil pH which

319represents the effective CEC (t), reflecting the dominance of

320permanently charged 2:1 clay minerals, which is in agreement with

321Simas et al. (2006). In surface, small amounts of Total Organic Carbon

322account for the pH-dependent negative charges that contribute with

323the slightly higher CEC at pH 7.0. Soil texture ranges from loam at

324surface to Sandy Loam in deeper horizons.

3253.3.5. Scree slopes

326These are the most frequent landform in Keller, with approxi-

327mately 25% of the total area, and are concentrated in the western face

328(Fig. 2). Northwards, these scree slopes are replaced by talus, and

329escarpments. Downslope, scree deposits are more stable, allowing

330limited vegetation cover to develop. However, scree slopes are very

331dynamic features, being subjected to strong erosion under paraglacial

332conditions.

333These are areas of active transport of rocky debris, normally below

334talus and mountainous terrains. The summer flow of water-saturated

335regolith isgreaterin acid soils, due to theirfiner particle sizes, butoccurs

336even in basaltic materials with larger rock fragments. Creeping of

337unconsolidated sediments appears to be a slow process, as many areas

338of basalt dykes cutting tuffs and other andesitic lithologies display only

339short-range redistribution of rock fragments downslope as thin scree.

340Thus,it appears that most rock fragmentspresentat midto highslope of

341Keller Peninsula are, in fact, the results of in situ physical breakdown of342rock substrates, with only short range transport. These highlight the

343recent exposure of the landsurface formerly under protective snow.

344We have observed that creep (and solifluction in scree slopes) is

345controlled by some structural features of the bedrock, such as fault-

346lines, presence of unconformities and dykes. On the higher parts of

347Keller Peninsula, the overall cryogenic landscape is considerably

348stable and little long-range redistribution of coarse debris is actually

349ongoing. Generally, however, the widespread solifluction does not

350allow for the development of soils in these active scree slopes.

3513.3.6. Felsenmeer

352On most gentle slopes and rocky benches of Keller Peninsula there

353is a widespread stable, coarse, angular detritus accumulation on the

354surface, and field observations have provided evidence of its355predominant in situ origin following frost shattering of jointed

356volcanic bedrocks, particularly in the upper and steeper slopes,

357derived from periglacial process (Andr, 2003). Some moraine-like

358landforms of south Keller Peninsula area also appear to be

359Felsenmeers. The physical disintegration promoted by ice wedging

360along fractures,joints and bedding planes of volcanic rocks (andesites,

361basalts), gives way to in situ slabs of different sizes. Coarse, igneous

362volcanic rocks usually have greater sizes and little redistribution on

363scree slopes. Volcanic tuffs, either acid or intermediary, normally

364produce smaller fragments and finer silty sediments, with wider

365landscape redistribution, forming widespread scree slopes.

366The borders of Felsenmeer are re-fashioned by scree, in which

367reworked allochthonous materials are found. There, soil creep occur

368during snow melting, beingreadily distinguished by the redistribution




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of Usnea-covered gravels, moss turfs and rock fragments, downslopeat larger distances away from the source areas, where Usneaceae and

other lichens cover stable rock crests. Typical Felsenmeer uplands arestable and covered by abundant Usnea and other epilithic lichens,especially around the Birkenmajer Peak.

Turbic Cryosols dominate the Felsenmeers, and the accumulationof coarse debris results in good soil drainage, where illuvial organicmatter fills the cavities below the surface as permafrost is discontin-uous or sporadic Leptosols also occur in this soil complex. In small,

localized areas, skua (Catharacta lonnbergi) or Giant Petrel (Oceanitesoceanicus) nests result in the Ornithic character.

In areas where sulfide-bearing andesites are exposed, oxidationresults in sulfate formation and Thionic character. Pedon 19, Turbic

Cryosol (Thionic) represents a Felsenmeer formed from suchmaterialsand presents typical low pH,extractable P andexchangeableCa and Mg. This soil presented the highest value of Total Organic

Carbon which may be due to the combined effect of ornithogenic

386influence enhancing primary productivity, low pH and high Al3+,

387reducing organic matter mineralization by microorganisms. Organic

388substances and poorly crystalline minerals provide pH dependent389negative charges, resulting in higher total CEC in relation to the

390effective CEC (t).

3913.3.7. Cirques

392Four rock glaciers (glacial cirques) are observed in Keller Peninsula,

393from south to north: Ferguson, Flagstaff, Noble and Babylon, with

394decreasing age, respectively. Rock glaciers, in the sense of creeping

395permafrost (Haeberli, 2000), are important paraglacial features.

396These rock glacier cirques are paraglacial landforms, being the

397products of various former glacial advances, similar to those described

398by Nelson and Jackson (2002) in an Alpine cirque, under oscillating

399glacialperiglacial process. There, glacial landforms are influenced by

400sheeting and sub-horizontal bedding of igneous volcanic sequence,

401creating structural steps.

Fig. 4. Distribution of acid-sulfate soils and sediments on Keller Peninsula.




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402 3.3.8. Plateau

403 Some flat lying highland areas of Keller Peninsula, such as the

404 Flagstaff-Morro da Cruz, Tyrrell ridge plateaux and Binkenmajer

405 Plateaux may be relicts of previous warmer phases, suggesting a

406 greater age of the upland landscape. Soil data of these areas suggest a

407 polar desert pedoenvironment, with active salt weathering in the

408 higher parts (Simas et al., 2008).

409 These highlandflat areasare thought to result from a former larger

410

continuous structural surface under protecting cold-based ice, now411 exposed and under low erosion rates due to their flat topography and

412 permeable substrates, which allow water to percolate deeper, hence

413 protecting the landsurface. These planation surfaces are somewhat

414 similar to the cryoplanation benches described by Hall (1997) in the

415 South Shetlands, but some are located in the upper slopes. They are

416 surely not forming at the present time, as suggested by Hall (1992) for

417 such features in periglacial areas elsewhere in Antarctica. The

418 presence of a straight line of Usnea-covered Felsenmeer and ground

419 moraines on upland flats indicates the recent ice-retreat of Keller.

420 The progressive recession of small cirques and artes from the

421 eastern Keller Peninsula melting through channels is producing an

422 erosional rejuvenation of these plateaux, otherwise supported and

423 kept by sheets of stepped resistant rocks. Rockfall and talus formation

424 are common along the fractured borders. On the top, Felsenmeer of

425 rounded, weathered and matured gravels is found, except on the

426 Tyrrell Plateau, formed by silty, acid decomposed tuffs. Despite the

427 greater weathering of substrates, soils are shallow and salty, due to a

428 high exposure of upland soils to wind.

429 Another important aspect of Keller Peninsula is the very recent

430 (15 years BP) retreat of the snow line in north Keller, across the Noble

431 Glacier, exhuming an ancient system of valleys and structurally

432 dissected terrains which cannot be explained by the present

433 periglacial erosion. We suggest that these are fossil landscapes,

434 possibly formed in waning phases of Late Quaternary, with warmer

435 climatic conditions and longer permanence of periglacial conditions

436 and greater exposure. At that time, the Flagstaff and Noble glaciers

437 formed a single corrie. Similar relict features have also been described

438 elsewhere in the Shetlands (Schaefer et al., 2004; Serrano and Lopez-

439 Martinez, 2000).440 Due to the discontinuous nature of permafrost at these elevated

441 areas, we propose a complex of Turbic Cryosol andCambisols for these

442 plateaux. Pedon 17, Turbic Cryosol (Eutric) represents these areas.

443 The amount of exchangeable Na is high at surface and reduces in

444 depth.Wind-borne salt canaccumulate on the winter snow cover, and

445 be further redistributed in the soil with the subsequent summer melt

446 (Luzio et al., 1987). These authors found Na levels corresponding to

447 26.7% of the total CEC in soils of King George Island, suggesting a polar

448 desert pedoclimate in the uplands, corroborating data from Simas et

449 al. (2008), who also found high Na amounts in uplands soils from

450 nearby Arctowski Station. Soil pH, P and Ca2+ and Mg2+ values are

451 high, typical of basaltic and andesitic soils of this part of Antarctica.

452 3.3.9. Talus453 These landforms are formed by rockfalls and are widely present in

454 both sides of the divide, representing 8.6% of the total area. They are

455 particularly frequent in the eastern escarpment of Keller highlands

456 just below the mountain walls, cliffs and concave, upper rock glaciers,

457 such as Noble (beneath Birkenmajer Peak) and Flagstaff (below

458 Flagstaff MountTyrrell plateau).

459 Talus cones made of mixed debrisand large angular blocks develop

460 in fan-shaped debris slopes, subjected to frost weathering and upland

461 snow melting. These represent active short range transporting

462 surfaces, in which mixed angular debris are transported along

463 downslope, beneath the rocky escarpment.

464 The dynamics of plucking and rockfalls appears to be related to the

465 type of volcanic rock and the presence of fault lines. Different rock

466 types can experience quite different temperature variations under

467similar exposures. Exposed coarse-grain, fractured basalt appears to

468experience the highest surface temperatures, reflecting its low albedo

469and thermal conductivity (Gerrard, 1988) whereas fine-grained

470yellowish/grayish acid-volcanics have high albedo coupled with

471higher thermal conductivity. This leads to greater fragmentation and

472smaller gravel size in the case of acid-volcanic rocks, which also

473possess lower densities.

474Macrogelivation is the process resulting in basalt and andesite

475

boulders, and infl

uenced by jointing and cleavage lines. However, the476relationshipbetween rock fragment sizes and type of volcanic (acid or

477mafic) may be misleading, because coarse grained rocks are those

478least jointed, whereas fine-grained rocks have more closely spaced

479jointing. The youthfulness of these talus slopes and the steepness are

480not favorable for soil development.

4813.3.10. Protalus rampart

482Protalus in Keller Peninsula are debris mantles of short-range

483distribution, found particularly in the Ferguson Glacier (south Keller),

484where ice retreat started earlier. These glacial till deposits in Keller are

485not derived from large glacier domes, but rather from small rock

486glaciers coming from upland cirques and rocky amphitheaters. The

487progressive retreat of the ice cover in south Keller Peninsula is best

488illustrated by up valley recessional moraines, which indicate periods

489of stable conditions.

490Frequent freezingthawing cycles associated with water-saturated

491active layer are processes that increase solifluction and the formation

492of protalus (Serrano and Lopez-Martinez, 2000). They have been

493described as coarse debris mantles, with a close association with a

494talus source, and under slow movement. Three protalus were

495identified in Keller Peninsula (Fig. 2): the FergusonTyrrell, with a

496SW-NE orientation and approximately 420 m of length; the Noble,

497with NW-SE orientation and 260 m; and Speil, with NE-SW

498orientation and 290 m of extension. They sum up more than 5% of

499the total peninsular area. The most typical feature of these protalus is

500the presence of a depression on the back side, which probably results

501from rapid deglaciation during the Holocene. This depression is also

502observed in the Speil protalus.

503In this respect, Serrano and Lopez-Martinez (2000) considered504protalus in Keller Peninsula as rock glaciers; however, following the

505suggestion ofWhalley and Azizi (2003), they are actually protalus, as

506they do not occur between two mountain terrains of U shape

507valleys.

508Upslope the protalus landforms gelifluction was found to be an

509important process for rapid sheet redistribution of soil/regolith

510materials downslope, particularly where subsurface melt water is

511abundant. Riling is usually associated with gelifluction on finer

512materials, causing scree development, garlands, paralleled debris

513lobes and parallel-aligned mudflows to develop. This results in

514alternating clayey and gravelly soils in more stable benches. The

515process of soil movement seems to be greater on acid tuffs and

516andesitic lithologies, where regoliths are usually deeper, and surface

517rock-fragmentation is of limited importance. On the other hand,518gelifluction is less marked in basalt and other mafic lithologies, due to

519a greater stoniness of the surface due to frost shattering and stony lag

520on the landsurface. Gelifluction accounts for the development of

521protalus, in the form lobate crescentic sheets of stony pavement, at

522mid and downslope positions.

523In the lower level of protalus depression, frost action not only

524causes the formation of a thin silt crust layer at the surface, especially

525on andesitic or basaltic materials, but also on acid tuffs. These features

526are particularly frequent in the area just below the talus of Noble

527Glacial Cirque, where basalts and andesites are dominant. In many

528areas of active ablation these crusts are often observed in areas where

529some muddy sedimentary lag occurs.

530Turbic Cryosols and Leptosols form soil complexes at these

531features. Bird nesting activity and sulfate bearing substrates can




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result in Ornithic or Thionic characters, respectively. Pedon 24, TurbicCryosol (Thionic) is typical of sulfate-affected protalus andhas low pH(b5.5), P and Ca2+ and Mg2+.

3.3.11. Rock crests and outcrops

These are landforms of structurally-controlled, resistant rocks,either forming platforms or crests. On flat tops overlying basalt

platforms of south Keller, Lithic Leptosol (Gelic) occur (Pedon 10),

associated with Turbic Cryosols (Skeletic) (Pedon 20). At lower rockcrest and outcrops, bird nests occur, especially skua (C. lonnbergi),resulting in a mixed vegetation cover composed by tuffs of

Deschampsia antarctica, Colobanthus quitensis, various mosses, crus-tose and fruticose lichens. Although shallow soils occur on the mostexposed rocks, deeper soils are formed in more preserved parts of thelandscape, reaching depths of 60 cm, and showing relatively high

amounts of organic matter and available P at the surface.

3.4. Other unmapped features

3.4.1. Sulfate-affected soils

An important landscape feature of Keller Peninsula is thewidespread occurrence of sulfide-affected rocks, from which sulfate-affected soils are formed (Thionic character). Generally referred to asacid-sulfate soils, they differ from the other pedons formed from

basalts and andesites, due to their acid pH throughout the profile,lower P, Ca2+, Mg2+ and higher Al3+ (Table 3, Pedons 19, 24 and 25).

Along sulfide-affected areas, acidity generated from sulfateformation through sulfide oxidation results in the acid drainage

phenomena, which favors solubilization and mobilization of iron andtrace elements. Non crystalline iron phases (ferrihydrite) andcrystalline iron sulfates (jarosite) are common in the clay fraction ofsoils formed in these environments (Simas et al., 2006). The

extremely low P-rem values reflect a high anion adsorption capacityattributed to poorly crystalline minerals (Schaefer et al., 2004). Thismaterial covers approximately 19.6% (1.2 km2) of the ice-free area inKeller Peninsula, occurring on eastern, southern and western faces

(Fig. 4) on different geomorphological environments, which were not

mapped in detail. Acidity generation due to sulfide oxidationenhances chemical weathering and formation of highly reactive,poorly crystalline minerals (Schaefer et al., 2004). In general acid-

sulfate soils in Keller have a higher proportion offine particles (siltand clay) andlower gravel and sand content in relation to basaltic andandesitic soils. This textural difference also has direct implications onrelief development and landscape functionality.

3.4.2. Biologically-influenced landforms

Biogenic landforms can be associated with any geomorphological

unit previously discussed. Although not mapped separately asgeomorphological features, these are examined as a particular aspectof landform evolution in Keller, as we observed their crucialimportance to landscape evolution. They cover approximately 30%

of the total area. Most chemical reactions actually ongoing on mostnortherly-exposed slopes in Keller are under the direct influence ofmacro and microorganisms. Epi- and endolithic lichens, cyanobacter-ial mats, mosses and ornithogenic inputs are of great importance.

Virtually all sites of exuberant plant cover are found or former birdnesting sites, in which phosphorous inputs are high (Simas et al.,2007), enhancing biological activity and changing the soil microcli-mate by high organic carbon inputs. Rather than an exception and

locally based, biogenic weathering should be amply considered as amajor factor in landscape development in paraglacial and periglacialenvironments, as recently suggested by Hall (1983), Etienne (2002)and Andr (2003) in periglacial areas.

There are many types of biogenic surfaces in Keller Peninsula.Fellfields are discontinuous vegetation covered surfaces dominated by

tall cushion and turf-forming mosses, occasional fruticose and

594crustose lichens and rare Deschampsia, usually associated with

595abandoned bird nest sites with higher biodiversity. Vegetation cover

596occurs on less than 3% of the total area. Algal mats are assemblages of

597mostly filamentous cyanobacteria or green algae forming biological

598crusts on wetlands, melting channels and seasonal melting lakes.

599Some are also associated with mosses on marine terraces.

600Mosses and a few liverworts occur whenever soils present high

601moisture, forming dense carpets, especially along the coastal terraces

602

and melting stream channels. In contrast, crustaceous and foliaceous603lichens are found on upland surfaces and top crests, ground moraines

604and stable Felsenmeer surfaces, areas of higher wind exposure and

605desiccation.

606Biogenic surfaces associated with a variety of landforms (e.g. rock

607benches, moraines, terraces, and protalus) are more stable with

608respect to gelifluction, and represent areas of relative sediment

609storage during snow melting. However, its capacity to retard

610sediment movement downslope is limited, as many eroded, biolog-

611ically stabilized moraines are found, dissected by surface water

612coming from ablation of upslope snow. Also, some turf exfoliation by

613needle ice occurs, particularly in low lying marine terraces covered

614with mosses and algal mats. Upland stripes appear to be related to

615strong winds or solifluction, with a trend of sorting and rounded

616pebbles and gravels of the upland tills, covered by epilithic lichens. It

617also appears that biologically covered landforms are less prone to

618freezingthawing mechanisms due to carbon sink into the soil,

619changing surface albedo.

6203.4.3. Lakes and ephemeral ponds

621Water released during the summer possesses enough volume to

622produce seasonal streams coming from rapidly retreating ice/snow

623fields. Although well-developed drainage systems are absent in Keller,

624like elsewhere in ice-free areas of Antarctica, there are numerous

625seasonal ponds and lakes of considerable geomorphological and

626ecological importance. The majority is situated behind marine

627terraces, rock outcrops, protalus and moraines, and most rest directly

628on permafrost or unweathered substrates. These were formed by

629damming of running meltwater in local depressions by recessional

630moraines, in the last 5000 years. A great number are located parallel631with the present coastline, dammed by marine gravelly terraces.

632These ephemeral ponds or permanent lakes can be salty and

633chemically rich (eutrophic), due to marine/bird inputs and rich

634sedimentary load. Cyanobacterial mats and diatoms are particularly

635abundant in the latter, especially on dark-gray basaltic silts, being less

636developed on yellowish acid tuffs. The amount of suspended material

637can be fully appreciated by large sediment plumes that reach the sea

638along the northern Keller Peninsula littoral, in both west and east

639margins. This is attributedto recent advanced melting in upland areas,

640yielding large amounts of fine particles derived from upland

641weathering, illustrating its paraglacial origin.

6424. Conclusions

643The main geomorphological and cryogenic features of Keller

644Peninsula are typical of mixed paraglacial and periglacial conditions,

645encompassing ice retreat process, snow melting and recent subaerial,

646ice-free landform development. Moraines, protalus, inactive rock

647glaciers, uplift marine terraces, and Felsenmeer were identified and

648quantified, where depositional features are dominant.

649Pre-glacial, relict landforms such as lateral moraines, highland

650plateaux and exhumed unglaciated valleys are now exposed in north

651Keller by recent ice shrinkage under former ice protecting cover.

652There, riling and snow melting coupled with the absence of moraines

653or stepped terraces in steep slopes coming down to sea level, all

654indicate the rapid ice retreat in this part of the Peninsula, ablation of

655recessional glacial cirques and subsurface melting is widespread. The

656active erosion under paraglacial conditions associated with active




13/13

657 relief results in unstable surfacewhere greater soil development is not

658 possible.

659 Little influence of marine birds is observed in Keller Peninsula,

660 hence ornithogenic sites are very occasional and form limited soil

661 inclusions in the different mapping units. Leptosols and Cryosols are

662 the most common soil classes, with an overall tendency of permafrost

663 absence in the coastal areas, grading to sporadic permafrost at mid-

664 slope, and discontinuous permafrost with greater altitude and

665

stability. The presence of permafrost-affected soils with Thionic666 character indicates the necessity of including such qualifier in the

667 WRB system and also the sulfuric qualifier for Haploturbels within the

668 US Soil Taxonomy.

669 5. Uncited references

670 Michel et al., 2006

671 Tarnocai et al., 2004

672 Acknowledgments

673 We thank the Brazilian Antarctic Program (PROANTAR) and the

674 Ministry of Science and Technology (CNPq) for financing the IPY

675 Project (CNPq, Cryosols of Maritime Antarctica). Logistical support

676 from the Brazilian Navy to undertake the field work, flights and

677 photograph cover of Admiralty Bay, is greatly appreciated. This is a

678 contribution of INCT-Criosfera, TERRANTAR group.

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