We appreciate the attempts of Marzec et al. (2019) to investigate the geological structure of the Pieniny Klippen Belt (PKB) by means of seismic-reflection profiling, but in our opinion the authors’ main conclusions contradict the results of previous studies without being constrained by the new data. Below we comment on some of the problems that led to the misinterpretation.

Marzec et al. (2019) retained two previously known major units (Pieniny–Branisko and Czorsztyn; e.g. Andrusov 1974; Birkenmajer 1986), and distinguished two additional ‘olistostrome belts', being part of two nappes: the northern Hulina Unit and southern Złatne Unit (Figs 2, 3 and 6). The Złatne Succession, besides the Jurassic and Cretaceous, consists of the Palaeogene (previously considered as post-orogenic strata) and Lower Neogene (Kremna Formation; Fig. 6). The youngest strata of the succession imply a Miocene age of a nappe-thrust of the Złatne onto the Hulina Unit, which contradicts the results of several earlier studies proving latest Cretaceous to Palaeogene thrusting in the PKB (e.g. Scheibner 1968; Birkenmajer 1986; Froitzheim et al. 2008). The idea of formation of the Złatne Nappe in the Miocene is also inconsistent with the fact that the Central Carpathian Palaeogene Basin, directly adjacent to the PKB to the south, is filled with autochthonous (not detached from its basement) post-orogenic Eocene–Oligocene sediments (Fig. 4; Janočko and Jacko 1998). Furthermore, the presence of the Miocene in the Złatne succession has no support in the data; earlier studies reported folded Miocene deposits exclusively in the Magura (Oszczypko et al. 2005) and Grajcarek (Hulina) units (Oszczypko and Oszczypko-Clowes 2014). In contrast, it was documented to the east in the Slovakian PKB that the Upper Eocene–Oligocene sediments of …