Aeolian processes and landforms in the sub-Antarctic: preliminary observations from Marion Island

Figures & data

Fig. 1  Location of study sites on Marion Island.

Fig. 2  A comparison of the particle size distribution of (a) the aeolian megaripples at Mesrug and the modified solifluction terraces at (b) Katedraalkrans and (c) Third Sister. Note the higher percentage of course material in the crest of the Mesrug megaripples with the risers of the solifluction terraces at Katedraalkrans and Third Sister.

Table 1 Summary of the particle size analysis of the sediment of the landforms surveyed at each study site.

	Third Sister			Katedraalkrans			Mesrug
Feature segment (wind direction)	Crest	Riser (windward)	Tread (leeward)	Crest	Riser (leeward)	Tread (windward)	Crest	Stoss (windward)	Lee (leeward)
Phi median	−2.20	−2.90	−1.09	−2.75	−3.25	−1.03	−3.11	−1.90	−1.71
Phi mean	−2.18	−2.88	−0.96	−2.66	−3.18	−0.60	−2.88	−2.08	−1.59
Skewness	0.05	0.19	0.44	0.27	0.28	0.28	0.20	−0.06	0.43
Description	Near symmetrical	Positively skewed	Very positively skewed	Positively skewed	Positively skewed	Positively skewed	Positively skewed	Near symmetrical	Very positively skewed
Sorting	1.58	1.48	1.88	1.34	0.84	2.75	1.67	1.51	1.76
Description	Poorly sorted	Poorly sorted	Poorly sorted	Poorly sorted	Moderately sorted	Very poorly sorted	Poorly sorted	Poorly sorted	Poorly sorted
Kurtosis	0.97	1.15	1.51	1.00	0.98	0.84	0.78	0.99	1.41
Description	Mesokurtic	Leptokurtic	Very leptokurtic	Mesokurtic	Mesokurtic	Platykurtic	Platykurtic	Mesokurtic	Leptokurtic

Fig. 3  Cross profile of average landform morphology. Arrows indicate the predominant wind direction over the crest of the landforms.

Fig. 4  Megaripple landforms at the study site near Mesrug, Marion Island. The staff is 1.2 m long (photograph taken on 20 April 2013).

Table 2 Wind characteristics and aeolian sediment flux for the study sites during the study period in 2013. Traps mounted at 0.05 m above the surface.

Site (m a.s.l.)	Measurement period (hours)	Mean ripple orientation	Mean wind direction, 0.5 m	Mean wind speed, 0.5 m (m s^−1)	Maximum wind gust (m s^−1)	Average sand trap mass (g)	Average horizontal mass flux (g cm^−2)	Aeolian sediment flux (kg cm^−2 h^−1)	Annual aeolian sediment flux (kg cm^−2 y^−1)
Mesrug (205)	17 April–6 May (467)	N–S	233.3	7.6	21.6	2.05	0.205	0.000439	3.85
Katedraalkrans (750)	19 April–4 May (369)	N–S	230.4	4.7	15.2	1.07	0.107	0.000290	2.54
Third Sister (244)	20 April–7 May (417)	WNW–ESE	273.4	7.3	18.4	0.17	0.017	0.000041	0.36

Table 3 Surface sediment creep/saltation collected at the study sites during the study period. The samplers were installed level with the surface.

Site (m a.s.l.)	Measurement period (hours)	Total mass of surface creep/saltation (g)	Mass (g) of sediment (sampling height 0–3 mm)	Mass (g) of sediment (sampling height 3–10 mm)	Mass (g) of sediment (sampling height 10–20 mm)
Mesrug (205)	17 April–6 May (467)	0.3	0.1	0.1	0.1
Third Sister (244)	20 April–7 May (417)	0.2	0.03	0.1	0.07