PONE-D-22-35505Creating frames of reference for chert exploitation during the Late Pleistocene in Southwesternmost Iberia.PLOS ONE

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Reviewers' comments:

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Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

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Reviewer #1: Yes

Reviewer #2: Partly

Reviewer #3: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: N/A

Reviewer #2: N/A

Reviewer #3: N/A

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Paper present an unedited work on raw material resources from southern Portugal. This work is well presented and introduced by reference to the scientific context. Methods are well explained and presented as well as their potential limits.

Reviewer #2: The manuscript led by Joana Belmiro entitled “Creating frames of reference for chert exploitation during the Late Pleistocene in Southwesternmost Iberia” are a type of works very interesting and important for the development of research on the territorial mobility of hunter-gatherer societies. In particular, this work focuses on southern Portugal, a region with important Upper Pleistocene archaeological settlements and with few detailed studies on possible source areas, in particular chert. Despite the great interest it arouses, the work reflects a number of limitations that need to be addressed in order to effectively help the development of the study of lithic raw materials and their catchment areas in this region.

Starting with general aspects, I will then go on to cite detailed aspects in the order of the manuscript.

If the aim of this paper is to create a good frame of reference for the identification of the different types of cherts in the archaeological assemblages by presenting the siliceous variability in the territory, first of all a geological map of the region has to be created, showing the siliceous outcrops in a clear way with their geological formations and with the outcrops individualised. General photographs of the outcrops would not be superfluous, as there is only one figure showing only one outcrop.

In relation to the nomenclature used to define each outcrop/variety of chert must be clear and consistent. It is not possible to talk about outcrops, chert varieties, geological age, indistinctly to ascribe each time to a group. Personally, I think it needs to be clearer.

Despite this work attempts to be a frame of reference for the chert source areas for southern Portugal, some archaeological context, I believe it is necessary.

In terms of structure, there are a number of shortcomings: in materials and methods, it must be clear what the starting point is, what materials are to be studied, and they must be well organised so that the presentation of data flows in a more organised way and following the same terminology. The results are divided into western, eastern and other outcrops, when this division does not make much sense and it would be better to divide them by geological periods. A more detailed petrographic description would also be needed in many cases. For example, presence of silica forms and percentages, matrix, replacements, porosities, autochthonous minerals...

The discussion should be contextualised with some archaeological sites, especially when talking about the important role of chert in the region. For example, line 570 states that all chert comes from the Jurassic formations. The only thing we note is that we only have chert from these geological layers in the region, but this does not mean that the chert found in the archaeological sites all comes from these formations. In the same way in line 623 comments that these studies will be very useful for the study of the lithic origin of the different archaeological levels of the Vale Boi site, but nothing is said about the archaeological assemblage, nor about the predominant raw material.

It is very interesting when we talk about the variability of chert in the same geological formation. This is a very common problem for all of us who study lithic provenance, so the attempt to find solutions is always welcome. In this case the identification is through the fossils content, which is not always possible. I think at this point the discussion could have been developed a little more. In addition, it contradicts itself (paragraph from 595 to 610). First saying that the fossils are hardly preserved and therefore this criterion cannot be used for their identification, and then that it is the only way to be able to solve the great homogeneity they present. This should be better clarified.

Finally, I fully agree that macroscopic as well as petrographic criteria are the best to establish provenance of lithic assemblages.

Specific comments:

In the abstract when you use the concept “use studies” you mean traceological studies? Better if you use this term or use-wear analysis.

Figure 1. Some more data is needed. Altimetry, name of geological formations, main geological units, some toponym. It will help to the lector to be able to situate when formations, geomorphological units, etc., are mentioned throughout the manuscript.

Line 180. There is an error when talking about Paleozoic sedimentation and it is mentioned that is starts during the Triassic. This also leads to a certain disorganisation when talking about the geological formations and sedimentary processes of the region as they are usually presented in chronological order, either by eras (Paleozoic, Mesozoic…) or systems (Triassic, Jurassic…). It doesn’t help much when talking about the Mesozoic and Cenozoic materials of the Algarve basin no reference about the Cenozoic materials are mentioned in the Geological settings. In general terms, the geological settings are somewhat confusing.

Lines 187 and 195. Paleozoic is mentioned again. Did you mean Mesozoic?

In subsection 2.2, it begins with the generalisation that the presence of chert is usually associated with carbonate formations of limestone and dolomite. This is not always the case, and even less in the Iberian Peninsula, where evaporite formations with chert nodules are abundant in the centre and north. I think this should be clarified, either by focusing on the study area or by mentioning the evaporite formations. In general, this subsection must be completed. The process of chert formation in these formations is not mentioned, is it related to the accumulation of siliceous skeletons on the seabed? How chert is formed? Also, all geological formations with cherts are not marked in figure 1. This will help to the lector.

Line 201. The error of lumping the Triassic and Jurassic formations into the Paleozoic continues.

Line 217. In the same way that chert formations can be associated with Middle and Upper Jurassic geological formations (Malhão and Jordana formations respectively), it is possible to know which geological formation carries the Lower Jurassic chert from the outcrops of Cabo S. Vicente and Praia do Belixe?

Line 277. Reference Soler et al 2020, must be changed by Gómez de Soler et al. 2020.

It is important to define which nomenclature you will use for mention the chert varieties: its outcrop name, ID sample, geological age, geological formation, variety and always use this nomenclature to refer to them. Is quite confusing.

Table 1. It would be good to add a column with the geological formation and another with the system or epoch. When talking about TSL - Thin Section Lab, to which laboratory do you refer? Specify.

Line 338. When citing figure 3, it would be better to divide it into 3a, 3b and 3c for quicker identification (this is also valid for the rest of the figures). In addition, it would be quite clarifying to be able to identify the dots with the outcrops, as throughout the presentation data figure 3 is quoted for outcrops but there is no way of knowing which ones it refers to. Also, the figures below need to have scale, as the only visible scale does not correspond to these figures.

Line 347. At the footer of table 2 I would remove the term “nodule” by “chert” as some of the outcrops chert’s morphology are not in the form of nodules, isn't that right? In the same table why the sub-primary ouctrops the morphology of the cherts is not given. In this case they would be blocks, wouldn't they?

Line 357. When talking about 3 varieties of Lower Jurassic cherts and you said that are grouped through color and fossil content, it would be easier for the reader if the colons and semicolons were followed by 1); 2) and 3).

Line 369. At the footer of figure 4 you need to add to figure 4a “Sample”.

Paragraph from line 373 to line 380 is confusing. If at the beginning you are talking about MCF variety and then for the microscopic analysis you are talking for all Lower Jurassic cherts you must add a full stop and specify that more than 50% of the samples that are not from, the MCF variety fossils are difficult to identify. If, on the other hand, you are always talking about the MCF variety, there is a major contradiction, when it is a variety with fossils content a naked eye, but then you affirm that more than 50% of the samples do not show them, then they are other varieties or this variety is poorly defined. However, at the end of the paragraph, when you quote figure 5, it corresponds to a sample of the MCF variety ¿no? No way to know it because in the footer of the figure 5 only de sample ID appears and no the type of chert variety (it is strongly recommended to add it, in the same way that in table 2).

Continuing with this confusion, from line 390 onwards, we no longer refer to varieties of cherts or geological ages, but chert outcrops to be divide them again into groups. It would help if it could be known which varieties of chert occur in which outcrops. It would help also some figures with the different types of chert outcrops and the location of these outcrops.

Line 392. The outcrops are said to have been divided into four groups but then five groups are cited: 1) Cabo de S. Vicente, 2) Foz dos Fornos, 3) Ponta dos Altos, 4) Praia do Belixe, and 5) Ferrel.

At the beginning of line 390 it is said: “Despite the similar characteristics between these cherts, the outcrops are heterogeneous and show varying characteristics between them, […]” but then when talking about FZF and PdA outcrops it is said that shows similarities to CSV ouctrop. Then why this division?

Line 415. Better refer to “secondary deposits” no “secondary deposition”. In this case, due to their proximity to the primary outcrop and, I imagine little roundness, it could be considered as a sub-primary deposit.

Line 447. When changing the subject from Lower Jurassic to Upper Jurassic outcrop types, it would be good to put a full stop. At this point it would be advisable to follow the same presentation scheme. If for the Lower Jurassic first the chert varieties are presented and then the outcrops, why for the Upper Jurassic first the outcrop is presented and then the macroscopic and petrographic characteristics.

Line 475. Subsection 4.2. It is important to present data in a clear, concise and homogeneous way. When discussing the Middle Jurassic cherts of the Malhão Formation, it would be good to cite first the localised outcrops and their locations throughout the text depending on what is to be explained at any given moment. It does not help to follow the reading in an easy way.

In figure 7, subfigure 7b cites an outcrop of such formation that has not been cited anywhere in the text.

Line 534. Subsection 4.3. Other outcrops are mentioned but their names are never mentioned and their locations cited. If the intention is to create a frame of reference for the scientific community on possible chert source areas, the presentation of the data needs to be clearer.

Line 551. At the beginning of the discussion it is commented that through the surveys it has been observed the enormous potential that the south of Portugal has for the study of lithic raw materials, especially chert. Readers are not aware of this, as only this raw material is presented in the manuscript, so this sentence should be qualified.

Line 552. In the results section as well as in the figures are organised in the west and east zone, it does not make much sense that now in the discussion let us mention the central zone of the south of Portugal.

Line 602. Figure 9, you must put a white background.

Line 668. Four different chert formations. Which ones? In the abstract is talking about three and in the manuscript are only two mentioned: Malhão Formation from Middle Jurassic and Jordan formation from Upper Jurassic. Formations, geological ages and outcrops are confused throughout the manuscript. This causes confusion.

In the references section, I believe that the authors do not follow the journal's citation form. In all of them the year is after the authors, the names of the journals are not abbreviated, nor is the type of separation between volume and number of pages. There are also some errors in the citation, for example:

Line 798. In Flügel's reference, the name of the book is missing (Microfacies of Carbonate Rocks).

Line 808. In Gómez & Lunt reference, the name of the book is missing (Phylogeography of Southern European Refugia)

Line 884. Incomplete reference.

Line 928. Incorrect reference, change Soler B.G by Gómez de Soler, B.

In supplementary materials, it is not clear to me that in the "outcrops_FULL_db" document the exact coordinates of each outcrop have to be given. We are all aware of the erosion of chert outcrops and the bad practices that occur in them. I think that with an approximate coordinate or quoting a geographical area would be enough. If there is someone with a scientific interest in knowing the coordinates, there is always a way to get them to you. This is just a personal opinion.

Reviewer #3: As it is mentioned in the title, the paper deals with the creation of a databse about chert types in the southernmost region in Portugal, and this for improving raw material studies of Late Pleistocene archaeological sites. The structure of the manuscript is clear and logical. The data presented in SOM are rich in information, The published Analysis dataset is very welcome not only for understanding the presented data structure and conclusions, but also for creating similar databases in other regions or countries. The description of the used methodology is complete and useful for those researchers who plan to make such kind of investigations. Data concerning the abundance and size and morphology of chert blocks at the source are highly important from an archaeological point of view regarding studies about raw material economy.

The text seems for me easily readable and understandable but I can not evaluate the level of English because I am not a native speaker.

I suggest minor revision concerning the following points.

When arguing in favour of creating reference databases of raw materials (line 125-128), the authors cite three cases related to an archaeological site, as well as the LIR of Ireland. However, there are important lithotheques in Iberia too (i.e. LITHICUB and LITOCAT in Barcelona). Moreover, the most important references in this field are the lithotheque projects in France (works and publications by V. Delvigne, J. Féblot-Augustins, P. Fernandes, A. Morala, A. Turq and others), where these researches started as early as in the 1980s.

As it is expressed, the main goal of the present study is to establish a reference for cherts in an understudied region, integrated into the LusoLit lithotheque (line 145-152); the geological samples studied came from fieldwork in 2021-2022, and the prospected locations were chosen after reviewing previously known research (line 253-261). However, it seems that the sampled locations presented in Fig. 3 already existed in LusoLit, as far as the Figure 1 of Pereira et al. 2016b (cited in the manuscript) can show it. For this reason, it would be welcome to read more about how the present study completed or enriched the former data of LusoLit (see line 261-263).

Besides macroscopic and petrographic (thin sections) analyses, the multilayered approach in raw material studies, as referred by Brandl 2016 in line 245, contains geochemical analysis too. A more complete description of this methodology was published by M. Brandl in Archaeologia Austriaca 97-98 (2013-2014) p. 33-58. Do the authors expect to make geochemical analyses too? If so, in what sens these analyses can improve the distinguishing between sources. If not, why.

The list of References needs to be checked thoroughly. There are typing mistakes, typographical faults (lower case/upper case), lacking bibliographical data.

Finaly, some corrections to verify.

line 32: Southwestern instead of Southernwestern

line 33: Cascalheira et al. 2017b appears first here, Cascalheira et al. 2017a only in line 276, change 2017b and 2017a along the manuscript

line 53-57: add a reference for Vale Comprido point and its association with the Heinrich Event 2 episode

line 180-201: Triassic and Jurassic formations belong to Mesozoic and not to Paleozoic

line 182: western and eastern (not oriental) sub-basins

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Reviewer #2: No

Reviewer #3: No

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PONE-D-22-35505R1Creating frames of reference for chert exploitation during the Late Pleistocene in Southwesternmost Iberia.PLOS ONE

Dear Dr. Belmiro,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Sep 15 2023 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Enza Elena Spinapolice, Ph.D

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

Reviewer #3: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Yes

Reviewer #3: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: N/A

Reviewer #3: N/A

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

Reviewer #3: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

Reviewer #3: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: This is my second review of the article led by Joana Belmiro et al. entitled “Creating frames of reference for chert exploitation during the Late Pleistocene in Southwesternmost Iberia”. After this revision, I can say that the article is definitely improved and several big issues I had with the previous version have been rectified, which I think definitely benefit the paper. However, as the article is intended to be a framework for future studies of raw materials applied to various archaeological sites in Portugal, some more precise data has to be included. I refer mainly to the geological formations with chert and their reflection in the manuscript, especially in figure 3. For example, in the case of this figure, it has been modified and improved, but since throughout the manuscript the geological formations with chert are mentioned, I think that a more detailed map including the geological formations would be necessary, and not just the series/epoch. I believe this is one of the keys of the manuscript to be a solid framework of reference on chert raw materials for further studies applied to archaeological sites. Nevertheless, the study is a definite improvement.

Regarding the general aspects I now agree with the comments of the authors to continue with the geographic division of western and eastern areas, but I advise to reinforce the idea in geological settings. Just add a sentence mentioning the use of this geographical division because of, as the authors rightly say, the differences in cherts and their formations.

Still on the same topic "frame of reference", although figure 2 has been improved and enlarged, as there are four chert formations, at least one photograph of each formation should be included. Some pictures of chert from Kimmeridgian formations?

Minor issues:

Line 334. When table S3 is cited, it should not be S2, in order to follow an order.

Line 366. At this point, here table S2 should be S3.

Line 378. Maybe it's me that's not working but I can't find the DOI in question.

Line 385. Results. Personally, I think there is still a bit of confusion between geological formation with chert, type outcrop, outcrop and sample. Although figure 3 and table 2 has clarified the data much more, looking at the detailed scale of the outcrops it sounds a bit strange to me that an outcrop, not a formation, has cherts covering a distance of almost 10 km. Wouldn't it be better to have the formation well defined and to have as many outcrops as points where cherts are found in the formation and that each point would take the nearby toponym to define the outcrop/location? This is in line with the general comment at the beginning that the delineation of chert formations greatly strengthens this work as a frame of reference.

It would also be helpful to have the outcrops mentioned in the text with their number and acronym before the figure. This would make it easier to follow the manuscript for those of us who are not familiar with the region.

Reviewer #3: (No Response)

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Reviewer #2: No

Reviewer #3: No

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Creating frames of reference for chert exploitation during the Late Pleistocene in Southwesternmost Iberia.

PONE-D-22-35505R2

Dear Dr. Belmiro

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Academic Editor

PLOS ONE

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Reviewer #2: All comments have been addressed

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Reviewer #2: Yes

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Reviewer #2: Yes

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Reviewer #2: Yes

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Reviewer #2: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: In relation to the revisions made, all the comments have been taken into account. Figure 3 is presented in a clearer way and it is easy to observe the situation of the formations and how they are divided between west and east, an aspect that gives even more sense to the division in the results proposed by the authors. The idea has also been reinforced in the geological settings by the authors.

Regarding the inclusion in Figure 2 of some images of the four formations described in the manuscript, this has also been corrected, as well as all minor issues have been fixed.

An unimportant comment, I have found some minor errors in the bibliography. I believe that with a small check will it be corrected. For example, line 1005 “Gómez de Soler BG” must be replaced by “Gómez de Soler B”, or line 1026 “Arsuaga L”, must be replaced by “Arsuaga JL, or some authors present their compound names separated by dashes and the rest do not... (example line 963 “J-P”, or line 959 “S-J” or line 966 “M-R”)

In short, I believe that changes have improved the manuscript, making it much clearer. After all the work done on the two previous versions I think the manuscript deserves to be published. Congratulations to the authors!

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Reviewer #2: No

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