This paper provides a fresh and valuable synoptic perspective on the LPIA in southern Africa. The paper will be of interest to many international geologists and geomorphologists. The focus is on establishing the extent of basement topography inherited in the present relief from the sub-Dwyka tillite unconformity surface. This erosion surface retains in places an impressive array of glacial erosion forms across scales. The extent of these glacial surfaces is claimed to be great – although the paper focusses on valleys rather than extensive erosion surfaces. The persistence of glacial surfaces from the Carboniferous is attributed to the geological recent erosion of Karoo group sedimentary cover.

The organisation of the paper needs to be significantly improved. The reader is currently led back and forwards in time. I suggest that, for each of the 4 study areas, the new and review information is presented for (i) pre-Dwyka geology, denudation and landforms, (ii) Dwyka glacial landforms and sediments and (iii) timing of re-exposure after post-Karoo erosion and Cretaceous to Cenozoic landscape development. This would allow the Discussion to draw together each strand more much efficiently. The novelty of the paper lies in the results for the pre-Dwyka and Dwyka surfaces.

The paper is currently badly let down by the incorrect use of terminology. Early in the Abstract and the Introduction, planation surfaces are included as landforms of glacial erosion. This is odd because even the voluminous textbook on Glaciers and Glaciation by Benn and Evans  makes no mention of planation surfaces as glacial forms. There is good reason for this – as a glance at Wikipedia shows. A planation surface is a large-scale, almost flat surface in geology and geomorphology. Common types of planation surfaces include pediments, pediplains, etchplains, and peneplains. These surfaces are cut across varied rocks and structures. Planation surfaces are mainly formed under fluviatile environments under the control of regional and local base levels. These are not glacial forms.

The sub-Dwyka unconformity surface is a glacial erosion surface. It has a different form to the younger surfaces described by Guillocheau and many others in southern Africa – these are smooth planation surfaces, mainly etchplains and pediplains - formed by weathering and erosion under fluviatile environments since the Cretaceous. When we look at the cross sections in the paper, we see that in all 4 study areas the sub-Dwyka surface is not flat. It has high relief, with deep (glacial) valleys cutting escarpments, and large hills and basins. The authors should make proper comparisons with Pleistocene glacial erosion surfaces of similar form on cratons in Baffin, Greenland, Scotland, Fennoscandia and Antarctica. All the main topographic elements found on the sub-Dwyka surface are represented in these regions.

There are two main reasons why glacial erosion does not tend to form flat planation surfaces. Firstly, unlike rivers, ice sheets do not respect base level. Glacial overdeepening demonstrates this. Secondly, glacial erosion is selective and strongly influenced by bedrock structures in hard, crystalline bedrock. In Precambrian basement terrain in North America and northern Europe, ice sheet erosion has formed landscapes of areal scouring or cnoc and lochan landscapes. These terrains have high relative relief and roughness, with hills and hills masses standing above deep valleys. The main valleys are excavated along faults and in major fracture zones. These glaciated basement surfaces are not smooth and flat. The effect of glacial erosion is to roughen originally smooth rock surfaces. We see this in the transitions from cold- to warm-based ice zones with decreasing elevations on mountain plateaux and at the edges of the cold-based centres of the former Laurentide and Fennoscandian Pleistocene ice sheets. Old, non-glacial surfaces are progressively stripped of regolith and fracture zones are excavated. Preglacial planation surfaces are dissected and destroyed. Look again at David Sugden’s zones of glacial erosion. Mathematical models of Pleistocene glacial erosion on elevated passive margins and in alpine mountains may be in error IMO and in any case have limited applicability to the LPIA in southern Africa.

In the text it is made clear that erosion during the LPIA is thought to represent an important phase of denudation, but the paper does not assess the depth of glacial erosion in basement. The depth of Pleistocene glacial erosion of shields has a long history of debate – similar questions have been asked about erosion of cratons during Snowball Earth and can be asked about erosion depths in the LPIA in southern Africa. Given the long duration of LPIA glaciation, pre-LPIA landform inheritance is telling us something about the effectiveness of ice sheet erosion on cratons.

Further issues in terminology include the following. The simplest term to describe the buried sub-Dwyka surface is as an unconformity. Clear evidence that the sub-Dwyka unconformity surface is locally preserved beyond sedimentary cover is provided by glacial landforms. But a clearer distinction needs to be made with the sub-Karoo unconformity surface where the Dwyka is missing and the cover is younger (Triassic). In both cases, an unconformity has been re-exposed and so revealed inherited relief. Re-exposure is included in exhumation, but the latter is a wider term that describes the relative movement of a parcel of rock towards the Earth’s surface during denudation or through melt or tectonics. Other terms used in the ms like resurrected and rejuvenated are not appropriate. I suggest that re-exposure is used when referring to unconformities in this paper and that exhumation is used in other contexts, including thermochronology.

On recent re-exposure, the modern rock surface and the sub-Dwyka unconformity surface remain at the same erosion level. This is inherited relief. Where glacial rocks and minor glacial landforms are not preserved but the wider topography retains an overall glacial form then we have persistent relief. Here, the modern rock surface stands metres to perhaps tens of metres below the former sub-Dwyka or sub-Karoo unconformities; the present erosion level is similar to but below the former unconformity surface. Where no inherited or persistent Dwyka or Karoo relief is preserved then the modern rock surface is at a greater depth below the former sub-Dwyka surface. That depth difference is hard to estimate and likely varies. The present surface forms may have been reshaped entirely by geologically recent processes. This latter point is important for understanding the development of the present surfaces on uplands between LPIA glacial troughs than were exposed to renewed weathering and erosion in the Neogene or longer.

The terms and related concepts are important for a correct understanding of where the sub-Dwyka and sub-Karoo unconformity surfaces and landforms fit into the long term history of denudation and relief development  on the cratons of southern Africa. Significantly, the authors make little mention of pre-Dwyka unconformities even though these are described in the geological literature. For example, in Namibia, the sub-Ediacaran unconformity is an extensive low inclination planar basement unconformity that locally lies close to the LPIA and the present erosion level. Palaeogeographic reconstructions show large parts of southern Africa exposed as land in the Cambrian.  Also, De Wit describes LPIA eskers resting on a polyphase erosional surface. Lister describes how the sub-Karoo surface in Zimbabwe is indeed extensive, but it is diachronous, has glacial and non-glacial surface forms. and was widely modified on uplands by Cenozoic erosion. Such comparisons are important because earlier writers like King and Lister clearly thought that non-glacial processes had contributed significantly to cratonic denudation before the LPIA. The pre-Dwyka denudation history in southern Africa is little known and warrants more attention. The authors recognise some major pre-LPIA landforms but do not carefully assess their character, form and origin in relation to geological structures or the extent to which these have been reshaped by glacial erosion. Too little mapped geological information is presented.

The main results concern the extent of the LPIA (Dwyka) glacial surfaces in the present relief. Results should be more clearly separated from review material. More information should be given on these glacial landforms, especially the supposed “planation surfaces”. The only morphological criterion for recognition of glacial valleys appears to be U-shaped cross profiles. Why not compare and contrast N Namibia with E Greenland or similar? Much of the reviewed and new information presented here is about glacial valleys. This is understandable –  sedimentary rocks in topographic depressions are often the last to be eroded out. The sub-Devonian valleys around the Cairngorms, Scotland, provide an example. However, the Devonian hills and mountains that once separated the Cairngorm valleys no longer exist, due to later erosion. Similarly, LPIA glacial valleys show that ice sheets may have covered the uplands that separate them but whether the present surfaces of the uplands carry inherited, persistent or younger forms often remains uncertain. This depends on the presence of Dwyka outliers or clear glacial bedforms and these appear to be of more restricted distribution on uplands between valleys than the authors imply. A key point seems to be that systems of LPIA glacial valleys are more widespread than previously thought. In turn, this indicates that pre-Dwyka uplands and escarpments remain as important elements of the present relief, as Lister recognised nearly 40 years ago.

The post-Dwyka history of denudation is reviewed at length in the context of the exhumation of the unconformity, but this is all review material and not new. This can be shortened, but some attention should be given to when sub-Karoo unconformities were re-exposed in different locations.

It is not acceptable to move from the main result  “over Southern Africa, an area of ca. 71.000 km² consists of exhumed glacial landscapes and 360.000 km² correspond to suspected glacial landscapes, which together correspond to ca. 10% of the total area of the region” to the interpretation of “vast and well-preserved glacial paleoreliefs” and “this modern morphology of Southern Africa is in fact largely inherited from glacial erosion associated to the Late Paleozoic Ice Age (LPIA).” Focus on what is attested, rather than suspected, and acknowledge uncertainty throughout. Just because a surface carries glacial forms does not mean that there has been deep glacial erosion. Consider southern Sweden where lowering of the sub-Cambrian uniformity by Pleistocene glacial erosion is of the order of 20 m.

My recommendation is for major revision. Fix the organization of the text and its terminology. Add information to the maps (geology, structures, ice flow, ice margins). Such revision need not be very time consuming but requires a more critical approach to what the evidence actually shows. Provide more reference to comparable Pleistocene landscapes of glacial erosion on shields. In the present ms, there a lot of loose expression, dubious logic, and occasional hyperbole in a paper that should have been scrutinised more carefully by its 13 co-authors. I have highlighted the worst cases in my detailed comments.

The manuscript “The Glacial Paleolandscapes of Southern Africa: the Legacy of the Late Paleozoic Ice Age” by Dietrich et al. explores the influence of Late Paleozoic glaciations on the modern landscapes of Southern Africa, using thermochronological data, geomorphological evidence, and stratigraphy to reconstruct past environments and burial/denudation processes. My field of expertise is in thermochronology, which allows me to assess the interpretations related to the thermal history and exhumation models presented in the paper. However, Sections 1, 2, and 3, which focus on the broader geomorphological context and historical geology of Southern Africa, fall outside my area of specialization, so my comments on these sections are based on general observations.

In general, I find the hypothesis presented in the paper—suggesting that glacial processes during the Late Paleozoic have left a significant and lasting imprint on Southern Africa’s landscapes—both interesting and worthy of further exploration. Nonetheless, the paper requires significant revisions, particularly in its reliance on localized data and the absence of broader, quantitative comparisons with modern glacial landscapes, which could better support its hypotheses. Some interpretations, specifically related to the thermochronological data, appear overstated without sufficient supporting evidence or acknowledgment of uncertainties inherent in the methods used. Furthermore, the manuscript would benefit from integrating alternative hypotheses and providing a more balanced discussion of the geomorphological features. Structural improvements, consistent referencing, and the inclusion of supplementary materials are also recommended to enhance clarity and strengthen the paper’s arguments.

Major comments are attached to this introduction.