Review of Jarosch et al. egusphere-2024-751 (Brief communication: Stalagmite damage by cave-ice flow quantitatively assessed by fluid-structure-interaction simulations).

This short report is an extension of the modelling described in Spotl et al. 2023, wherein fracture of cave stalagmites by cave ice processes was shown to be more likely caused by thermal expansion of the ice rather than by direct movement of the ice. The research reported here adds more conditions to the basic modelling, and shows that thermal expansion is confirmed as the most likely cause of stalagmite fracture and only in rare situations could fracture be attributed to ice flow dynamics.

The techniques used in the modelling appear to be sound and the conclusions justified. The paper is well written and clear. However, there is one glaring ambiguity in the examples shown to illustrate the process and asserted to be “examples of stalagmites damaged by ice during the last glacial period”.  

If a clear example is to be presented, then it must have ice action as the obvious and, ideally, only process that might have caused shattering. Figure 1 B and C are from Shatter Cave, Mendip, UK. Yes, this cave shows nice examples of cryogenic cave calcite deposits, so, yes, ice was present. However, attribution of the cause of the stalagmite shattering is very much compromised by the fact that the cave was only discovered, in 1969, as a result of quarrying, which started in the 1920s. It was named to commemorate the damage assumed to have been done by blasting. If this cave is to be used to support the idea of cryogenic fracturing, then I suggest it be made clear how the cryogenic fracturing differs from quarrying fracturing.  

Secondly, the assertion of the timing (that the shattering had occurred during the last glacial period) requires more proof. These examples show no obvious post-shattering cementation with calcite and no dates are offered.

Review of Brief communication: Stalagmite damage by cave-ice flow quantitatively assessed by fluid-structure-interaction simulations

Please note: As agreed with the editor this is purely a review of the ice/modelling part of this paper as I am not an expert in stalagmites. On that basis I am not in a position to either recommend or not recommend this paper for publication but can provide comments on the modelling and the paper in terms of suitability for The Cryosphere.

The paper builds on the work of Spötl et al. (2023) that examines the effect of internal deformation within a cave ice body on stalagmite damage by investigating the effect of this deformation within the stalagmites and by looking at smaller stalagmites.

My main suggestion for this paper to be published in The Cryosphere would be more context. Although this is a brief communication, as this is not a journal where many readers are going to have knowledge of speleotherms, why this work matters needs to be made much more explicit. This is especially the case given the previous work it builds on had already ruled out ice flow as a mechanism, why did this justify looking at this in more detail, and still getting a result that the process here is likely to lead to fracture? Why is mechanical damage to stalagmites important?

Line 20: How do these relate to stalagmite sizes in previously glaciated regions?  Are these typical sizes, and are the new smaller sizes included here also typical?

Line 23: Do you use a sliding law here? If so please specify and cite.

Line 30: Did you do any sensitivity testing on any of the parameters? E.g. recent studies have shown that the assumption n=3 in Glen’s flow law does not always hold (for example see Millstein et al. (2022) https://www.nature.com/articles/s43247-022-00385-x)

Line 32: Citation needed for this choice of linear elastic.

Line 47: Rather than listing simulation numbers which mean little to the reader this paragraph could highlight better the conditions of the simulation that do find failure.

Line 66: Is this realistic given in some simulations you’re assuming a full-slip condition at the bed, will ice be fully frozen to the stalagmite? You later go on to say full-slip conditions are highly unlikely but if they are worth considering here then why not also for the stalagmite?

Line 70: Please add more detail on why these values are an overestimation.

Line 94: Could a combination of these processes be occurring?