the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 13 Aug 2025
A high-resolution dataset of Rock Glaciers in the Peruvian Andes (PRoGI): inventory, characterization and topoclimatic attributes
Abstract. Rock glaciers are key periglacial landforms in high mountain systems, serving as indicators of permafrost, contributors to mountain hydrology, and sentinels of climate change. Despite their scientific and practical importance, detailed knowledge of their distribution, characteristics, and dynamics in the Peruvian Andes remains limited. This study presents the Peruvian Rock Glacier Inventory (PRoGI v1.0), – a comprehensive, high-resolution inventory of rock glaciers covering the entire Peruvian Andes, encompassing their spatial distribution, morphological attributes, and topoclimatic controls. Unlike previous local-scale studies, PRoGI v1.0 provides national-scale coverage using standardized methods aligned with International Permafrost Association (IPA) guidelines and updated data. Using sub-meter satellite imagery (Bing Maps 2024 and Google Earth 2017) and IPA classification standards, we mapped 2338 rock glaciers with a total area of 94.09 ± 0.05 km². Approximately 31 % of these landforms were classified as active, 49 % as transitional, and 20 % as relict. They predominantly occur between ~4416 and 5783 m a.s.l. (mean elevation ~4999 m) on slopes averaging ~20.7° (range 7–37°). Spatially, rock glaciers are concentrated in the southern Peruvian Andes, with sparse distribution in central and northern Peru. Most have a southern to southwestern aspect (predominantly S, SW, and SE-facing), and the lower limit of permafrost (indicated by the lowest active rock glacier fronts) is ~3541 m a.s.l. Our inventory serves as a benchmark dataset that significantly advances the understanding and monitoring of mountain permafrost, and it provides a basis for assessing the hydrological importance of rock glaciers in the Peruvian Andes under climate change scenarios. The dataset is available at https://doi.pangaea.de/10.1594/PANGAEA.983251 (Medina et al., 2025a).
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RC1: 'Comment on essd-2025-390', Anonymous Referee #1, 07 Sep 2025
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AC1: 'Reply on RC1', Hairo Léon, 29 Sep 2025
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We thank Anonymous Referee #1 for their thorough and constructive review. We will implement the following changes:
- Primary markers (PM): We will generate and release a dedicated PM layer (point features) for each RGU/RGS, following the RGIK/IPA guidelines (unique IDs, WGS84 coordinates, attribute linkage). This PM layer will be added to the public dataset.
- Repository: Our dataset is archived in PANGAEA because it meets the FAIR criteria, which meets ESSD repository criteria. We will upload a new version including the PM layer (and updated metadata).
- Figures and layout: We will replace redundant tables with high-quality figures (national map + key distributions: elevation, aspect, slope, activity classes; lower permafrost limit map) and improve figure resolution/legibility.
- Methods/results separation: We will move quantitative findings currently in Data to Results and streamline duplicated paragraphs (data sources; identification criteria), improving readability and conciseness.
- Topoclimatic interpretation: We will clarify the temporal scope: modern topoclimatic variables are used as proxies of current environmental controls on mapped distributions, not as direct indicators of formation timing. We will expand the discussion on lags and limitations.
- “High-resolution” definition: We will define it explicitly (imagery spatial resolution, mapping scale, and minimum mappable size) and contrast with previous inventories.
- Analysis with MAGT model (Obu et al., 2019): The more detailed analysis you suggested will not be carried out, given that the model has not been validated regionally. Therefore, the current qualitative comparison will be maintained as a contextual reference, and an explicit warning about these limitations will be added.
- Organization and redundancy in the text: We will reorganize the logical flow throughout the manuscript, eliminate redundancies, and restructure the content if necessary to improve the readability of the document.
We appreciate the reviewer’s suggestions and will submit a Final Response and a revised version addressing all points in detail.
Citation: https://doi.org/10.5194/essd-2025-390-AC1
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AC1: 'Reply on RC1', Hairo Léon, 29 Sep 2025
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- 1
The authors of this paper produce the first national-scale rock glacier inventory for the Peruvian Andes region with a coverage over 300000 km2, and use quality control and cross-check to improve the quality of the dataset. This dataset has high quality and is important for the permafrost and mountain hydrology studies in Peruvian Andes. However, the wording of this paper is too long with many places showing redundant and repetitive information. I suggest this paper should improve the organization, readability, and concreteness before publication. See my comments below:
General comments:
Specific comments:
Line 1: Please explain what makes this inventory ‘high-resolution’, if it is because that this inventory was created using Bing Map and Google Earth, I don’t think the ‘high-resolution’ can be a highlight or advantage of this inventory as many previous inventories were also created using high-resolution Google Earth imagery.
Lines 43-63: These two paragraphs, first introduce rock glaciers, then permafrost, then rock glaciers, which reads wield. Suggest reorganizing the content, better to describe permafrost first, then introduce rock glaciers.
Line 68: “Splitting it up would reduce run-on complexity => What does it mean?
Line 100: In total, 2338 rock glaciers were mapped using these optical datasets (2095 from Bing and 243 from Google imagery) => These are results, should not appear in the Data section
Line 101: Please explain what makes this dataset complete and high-resolution
Line 105: We compiled several auxiliary datasets => topoclimatic datasets?
Lines 137-140: We primarily used Bing Satellite…Google Earth imagery for that grid cell => similar information has appeared in section 3.1 Data sources Lines 93-96: Bing Maps Aerial imagery was used as the primary data source…geodatabase creation. Suggest merging the information and write it in one place, otherwise, the readability of the paper can be reduced with many redundant and repetitive information in different places.
Line 149: Only longitudinal ridges and furrows? No latitudinal ridges and furrows?
Lines 190-217: Section 4.2 Geomorphological identification criteria: To me the Bullet point and the table are also redundant information, only keep one of them is enough (only the information in Table 2 is enough, no need to write repetitive words using Bullet points.
Lines 231-241: Again, Table 3 is sufficient to show everything clearly, no need to repeat the information using Bullet points.
Lines 250-266: What is the difference between this paragraph and Section 4.2? In section 4.2 you already describe the geomorphological identification for rock glaciers of different activities, why mention the repetitive information here?
Line 291: The smallest rock glacier included in the inventory has an area of 0.001 km², the minimum area threshold for inclusion, according to the IPA guidelines (RGIK, 2023) => Are you sure the minimum area threshold suggested by IPA guidelines is 0.001 km² but not 0.01 km²?
Line 130: 4 Methodology => The Methodology part should be reconstructed, reducing the redundant and repetitive information and making the literature more concrete. Suggestions on the subsections could be 4.1 Identification and mapping of rock glaciers 4.2 Classification of rock glaciers 4.3 Topoclimatic features 4.4 Inventory compilation and validation 4.6 Uncertainty assessment
Line 350: Morphological types: => I suppose this should be a subsection 5.2.1 Morphological types? Also the Line 357 5.2.1 Rock glacier activity: => delete ‘:’
Lines 350-356: Why the analysis of morphological types is not as long as rock glacier activity?
Line 378: he NWOT and NDOT => I suppose it should be ‘The NWOT and NDOT’.
Line 392: Elevation distribution: => I suppose it should be a subsection 5.3.1 Elevation distribution here.
Lines 392-402: For the unit of elevation, some places are m a.s.l. Some places are m. Please keep them consistent.
Lines 434-439: This paragraph is not about Aspect, may you use miss the subsection?
Lines 439-443: ‘This distribution reveals that elevation is the primary control on the presence of rock glaciers, with secondary hydrothermal modulation - evidenced by inverse AP-MAAT relationships in NDOT/SDOT/SWOT (where aridity and snow redistribution at elevation increase cooling) versus the direct correlation of NWOT (driven by thermal depression mediated by microclimatic processes). Such systematic variations underscore how Andean rock glaciers integrate macroscale climatic gradients with local topoclimatic processes.’ => Why elevation is the primary control and climatic conditions are secondary? I don’t understand how this conclusion was drawn from the results.
Lines 453-454: Individual rock glacier area uncertainty was found to range from as low as ~0.001 km² for small, clearly defined features to up to ~0.3 km² for very large or diffuse features, with a mean uncertainty of ~0.06 km². => A figure between uncertainty and area would be helpful.
Lines 504-514: I would expect more results about the comparison between the rock glacier distribution (active, transitional, relict) and the distribution of permafrost from Obu et al. (2018) instead of just stating the elevation and MAAT. Maybe better to show some example figures showing this distribution comparison, see whether the active ones are within the permafrost and the relict ones are out.
Lines 518-519: “The comparisons with global inventories (see Table 8) show that while Peru’s rock glaciers are extreme in elevation, other characteristics like slope and aspect are broadly similar to rock glaciers elsewhere” => But Table 1 only shows the elevation and does not show other characteristics like slope or aspect?
Line 537: see my general comments, not sure whether it is reasonable to use modern climate to discuss the distribution of rock glaciers as these landforms are something happened hundreds of years ago.
Lines 555-557: “The correlation of the inventory with modelled MAGT data (Obu et al. 2019) provides an independent check: nearly all active, rock glaciers lie in grid cells where MAGT is at or below 0°C, whereas relict rock glaciers occupy cells where MAGT is just above 0°C (indicating marginal permafrost conditions).” => See my comments above, I would expect more elaboration on this part. Maybe a statistics on the MAGT of the rock glaciers with different activities, or some examples showing the distribution of rock glaciers and the permafrost.
Line 675: ‘his opens’ => This opens?
Line 692-694: “Looking forward, several lines of future work are planned based on this inventory: Temporal monitoring: now that this baseline is set, repeat satellite observations (e.g., in 5–10 years) or the analysis of time series (like the 2017 vs 2024 imagery) could reveal if any rock glaciers are retreating at the margins or if new ones are forming” => The development of rock glaciers typically take hundreds of years (totally different from glaciers), I don’t think you would see significant changes on rock glaciers on decadal scale.