Permafrost active layer thickness was investigated in the vicinity of J.G.Mendel Station (James Ross Island) along a 5.4 km long transect ranging from the altitude of 4 to 323 m a.s.l. Climate conditions and altitude were the main factors, which control the thickness of active layer at 12 study sites. The negative correlation between the depth of permafrost thawing and altitudes was modified by water content in regolith and deflation processes, which reduced the downward propagation of active layer.