The considerable areal extent and a great thickness of Middle/Upper Triassic carbonate sequences favourably influenced the development of paleokarst during the Paleoalpine karst period in the Brezovske Karpaty Mts. Carbonate formations provide data concerning the first-pre-Gosau-phase of the Paleoalpine karst period. Freshwater limestones, bauxites, reddish ferrugineous silty clays, Valchov Conglomerates, shallow doline-like depressions and deeper canyon-like forms represent the most important pre-Gosau karst sediments and forms.