Variations in δ18О values in the Late-Pleistocene (pIW) and Holocene (hIW) ice wedges and segregated ice schlieres (SIS) ices of Ayon Island.# = Isotopic analyses were performed at the Institute of Water Problems, RAS and at the Institute of Geology, the city of Tallinn. Oxygen isotope measurements of ice wedge were carried out in the isotope laboratory of the Institute of Geology of Estonia (Prof. R. Vaikmae) using a Finnigan Delta-E mass spectrometer. Analytical precision was ±0.4‰ and in the isotope laboratory of the Institute of Water Problems RAS (Dr. A.Yesikov) using a Finnigan MAT 250 mass spectrometer. Analytical precision was ±0.6‰.