Conceptual Model of Permafrost Degradation in an Inuit Archaeological Context (Dog Island, Labrador): A Geophysical Approach
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis is an excellent paper as it stands; therefore, I have very few comments. The interaction of permafrost with archaeological sites in the arctic and subarctic is an important process, and as the authors discuss, in the context of modern climate change we need to understand it in order to make appropriate decisions regarding the management of the heritage record. Furthermore, the authors do a nice job of describing their work and, in particular, comparing the results of the different remote sensing methods. They make a good case for their complementarity. I recommend publication more or less as is. There are a few typos which the proofreaders will catch, and I also offer the following very few and minor suggestions:
Line 76: "Nordic" is not the right term here - presumably "northern", "high latitude", or "arctic" would be better.
Line 178: Text refers to 6 profiles, but figure seems to indicate 5.
Line 548: Omit "The properties of".
Line 584 ff. I found this final concluding section to be the only part of the paper that I questioned. There is a vast literature on this topic (responses to climate change impacts on archaeological sites) and this coverage seems inadequate and arbitrary. My suggestion would be to reduce the final two paragraphs into a more general statement on how the info in the paper is crucial for the management of sites in permafrost environments.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsDear Authors,
Somme comments are in your attached PDF manuscript. And the more specific ones follow:
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This manuscript presents an interesting geophysical study in order to obtain the archaeological context of an Inuit site, but the authors should improve the manuscript.
Against this background, I would like to make the following comments:
Comments concerning the TITLE
The actual title is not well written. The authors should modify it and establish
the hierarchies correctly…. For example:
Geophysical approach to obtain the model of permafrost degradation in
theInuit archaeological site Oakes Bay 1, on Dog Island (Labrador, Canada)
Comments concerning the Abstract
In pdf manuscript I put some comments.
In my opinion, the sentence on lines 21-22 should go before that the sentence on lines 20-21.
In general, authors should Improve the wording of the abstract.
Comments concerning the 1. Introduction section
Lines 81-86. This paragraph would be better placed in the “2. Study Site” section.
Comments concerning the 2. Study Site section
In my opinion, figures 1 and 2 should be placed in this section, since they both refer to the study area.
Lines 123-129. See the comments in the PDF file.
On the other hand, the authors should improve these two figures so that the text is better understood.
Figure 1 could be improved a little. And to distinguish the archaeological site.
Figure 2 is too dark. The legend and the tags are too little.
Comments concerning the 3. Methods section
The authors should improve the presentation of the methods used. In its present form it is not clear (li nes146 to 156). See the See the comments in the PDF file.
3.1 ERT method
Lines 184-188. The authors could put some references for the inversion ERT data algorithm. This is the crucial and important point in the processing flow.
Another aspect is that the authors set the RMS limit fit at 5%, but they do not
indicate the number of iterations with which the final model has been obtained. This
number should be included in the final models.
Other comments in the PDF file.
3.2 GPR method
Line 207. The authors could put the dielectric values of thawed and frozen ground; it is important information that should not only be in the references.
Lines 215-217. “To assure consistency between the data from the different methods, the topographic data was exported from the DEM model and then imported to the dataset for topographic adjustment of the transects”.
This phrase is an "abuse" of language. Because whenever there is relief, topographic corrections must be applied; whatever the geophysical method used.
Lines 220-222. The authors could be put the relation between resistivity and velocity of the electromagnetic waves they have used. They must also give their equivalent dielectric constant.
On other hand a 0.07 m/ns seems not gut for the permafrost table because their equivalent dielectric constant ranges 10-30 corresponding a silts materials.
Philip M. Reppert, F.Dale Morgan, M.Nafi Toksöz, Dielectric constant determination using ground-penetrating radar reflection coefficients, Journal of Applied Geophysics,Volume 43, Issues 2–4, 2000, Pages 189-197, ISSN 0926-9851, https://doi.org/10.1016/S0926-9851(99)00058-0.(https://www.sciencedirect.com/science/article/pii/S0926985199000580)
Line 226. There is an error in this line. The authors could revised the skin depth and power absorption (P) equation concept. The GPR wave attenuation between the shallow materials and the top of permafrost layer is due to the dielectric contrast (impedance //refraction-reflexion coefficients) .
General comment: GPR data processing is not explained, and final profiles are poorly processed. No basic processing seems to have been applied: back-ground removing, ban-pass filters, AGC, etc….. So, the final profiles are poor and their interpretations unreliable.
The authors could to re-processing the GPR-profiles.
Other comments in the PDF file.
Comments concerning the Section: 4. Results and Interpretation
Figure 3. Put the permafrost table in same size of the other tags. We cannot see.
4.2. Electrical resistivity tomography (ERT)
Figure 4 could be improved.
- Use only one resistivity colour scale for all profiles
- The map (F) could be Figure 2 is more clear
- The ERT profiles are not visible; they should be bigger. should be bigger.
- The vertical scale should be exaggerated and remove the location map
A general comment:
My experience with ERT profiles in resistive media and with topography is that bad (negative) apparent resistivities are measured. So, before processing the data, filters have to be applied to avoid these bad data which usually occur between extreme resistivity values. This reduces the number of useful measures. The authors should mention if this has happened to them, especially when they have been forced to use salt water for the electrode contact.
In addition, in these environments, the RMS setting is usually somewhat higher than 5%.....
On other hand, the geoarchaeological approach is very good.
Comments for author File: Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsSummary: I read the manuscript carefully, which concerns “Conceptual model of permafrost degradation in an Inuit archaeological context (Dog Island, Labrador): a geophysical approach”
A conceptual model of the contemporary geocryological context of the subsurface with relation to the site's topography, hydrology, and geomorphology has been suggested, utilizing a novel methodology in northern geoarchaeology based on non-invasive geophysical tools (coupling GPR, ERT, and EMI). The active layer thickness was accurately estimated, and the geographical variation and features of permafrost were imaged using ERT and GPR. Using the results of the geophysical studies, the permafrost at Oakes Bay 1 was classified as an ecosystem-protected, climate-driven permafrost that is incapable of regenerating in the present environment. The permafrost at Oakes Bay 1 is very vulnerable to climate change because of multi-point thermal deterioration caused by both conduction and advection, as this paper illustrates.
To be a useful contribution to the geophysical literature, I believe the paper needs some minor adjustments which can be made., as well as language refining and editing.
All my comments and more details are included in the attached file.
Comments for author File: Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for Authors1.- I still don't like the title, but I accept it in its present form.
2-In some paragraphs of the manuscript the authors cite EMI methods, but do not present their results.
I am of the same opinion as them to remove this method from the article, but then they should also remove their references.( line 23- Figure 3 Section 3.3.)….. I have marked them in the PDF file.
3- I still don't like the GPR processing, but as some correlation with the electrical units is visible; I overlook the poor treatment applied.
This can be seen very well in Figure 8. The two B-scans presented appear to have no basic treatment applied. For example, the flow: 1) remove banck-ground, 2) predictive deconvolution, 3) ban-pass filtering and 5) AGC.
In this context. The authors should provide the basic processing flow that the raw-GPR data has undergone.
Comments for author File: Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
