Dear colleagues,

The paper covers relevant scientific topics and is very important to understanding the natural processes that took place in the Caspian Region. I consider the paper to be of high value in general,  but I would like to address certain comments that would add correctness to the paper.

The review of the positions about the age of the Early Khvalynian transgression (lines 45-50) leads to the conclusion that prior to 1990s, there existed belief about the synchronous nature of the Early Khvalynian transgression and the Early Valdai (Early Weichselian, MIS 4) glacial epoch. Then, (referenced Svitoch et al., 1994, 1998), emerged a notion about a “young age” of the transgression based primarily on the radiocarbon data. However, these points of view existed concurrently and were the subjects of fierce debate in scientific community. A.A. Svitoch (whose works are referenced in your paper) defended the position on the “young” age of the transgression even as early as in 1970s. But the scientists who supported the other point of view (G.I. Rychagov, V.A. Zubakov) persisted in their opinion and believed that the radiocarbon method yielded faulty results (and later, the OSL method) and was not suitable for dating of the Lower Khvalynian sediments.

Furthermore, the interpretation of the conclusion on the age boundaries of the Khvalynina transgression reached by R. Makshaev and N. Tkach (2023) is not entire correct. R. Makshaev and N. Tkach (2023) presented analyses of not 180 dates, but of 234 (these represent all the radiocarbon dates available to date) and for the entire (!) Caspian. They did not identify two transgressive events in the Early Khalynian post LGM (as you present in the paper), but conjectured on the position of the levels at separate time segments based on the radiocarbon dates.

Besides, the radiocarbon and OSL dating correlate well and therefore, it doesn’t seem to be quite feasible to consider only OSL dating for the Lower Volga Region when building models for the entire Caspian.

The presented paper does not consider the Manych Strait, which played an important role in the Early Khvalynian basin. Therefore, how the Manych strait affected to the changes of water balance of the Early Khvalynian basin from the post-LGM to the Allerød? In addition, it is necessary to consider the existing radiocarbon and OSL dates obtained from lower Khvalynian deposits of Manych (Svitoch et al., 2010: Pleistocene of the Manych. Questions of the structure and development; Semikolennych et al., 2022: Dating the Khvalynian strait within the late Pleistocene history of the Manych Depression).

It is necessary to correct some inaccuracy in the text.

For example:

Line 56:  Yenotaevian regression

Line 563: Yenotaevkian regression

Line 676: Chepalyga, A. L.: Late glacial great flood in the Ponto-Caspian basin, in: The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement, edited by: Yanko-Hombach, V., Gilbert, A.S., Panin, A., and Dolukhanov, P.M., Springer, Dordrecht, 119–148, https://doi.org/10.1007/978-1-4020-5302-3_6, 2007.

Among the editors - Nicolae Panin from Romania, not A. Panin

Line 823: Rychagov, G.I.: Late Pleistocene history of the Caspian Sea, in: Comprehensive Studies of the Caspian Sea, edited by: Leontiev, O.K., Maev, E.G., MSU Press., Moscow, 18–29, 1974 (in Russian).

Line 855: Svitoch, A. A., and Yanina, T. A. (Eds.): Quaternary Deposits of the Caspian Sea Coasts, MSU Press, Moscow, 267 pp., 1997 (in Russian).

Not entirely clear "(Eds.)." Editors? This is a monograph of two of these authors.

Line 871: Varuschenko, S. I., Varuschenko, A. N., and Klige, R. K. (Eds.): Changes in the Regime of the Caspian Sea and Closed Basins in Paleotime, Nauka, Moscow, 239 pp., 1987 (in Russian).

The same. Not entirely clear "(Eds.)"

And as the conclusion: Thank you for the interesting paper.