Stratigraphy, Petrography and Grain-Size Distribution of Sedimentary Lithologies at Cahuachi (South Peru): ENSO-Related Deposits or a Common Regional Succession?
Round 1
Reviewer 1 Report
The analyses presented here are sound and clearly presented, but the framing of the paper renders the whole paper somewhat confusing. The focus on Grodzicki's proposals about ENSO-derived flood deposits accurately identifies an interesting question, but it's not clear that the evidence and analyses presented here are actually appropriate to address that question. Further, given the focus on Grodzicki's assertions, they are only minimally described - we don't know how the sediments he describes were dated, or how exactly they relate to those described here. Identifying those sediments, and/or ascertaining their relationships to those described here, seems fundamental, but is also barely addressed.The stratigraphic relationships and dates of the deposits - and archaeological features - concerned are critical to any interpretation, but they are barely discussed.
The English is clear and comprehensible, particularly in the methods and results section, but the syntax should be reviewed by a native speaker.
Specific comments on the text:
Abstract
Lns 17 and 25 In the abstract (though not in the text) 'palpa' is used where 'pampa' is meant.
Ln 24 The ‘mainstream explanation' is that of two ENSO-related flood deposits at ca. 600 and 1000 AD? Unclear how a pre-Cahuachi (i.e. first millennium BCE) deposit should test this.
Main text
Ln 37 "This statement derives from an interpretative geological setting" - not clear what is meant by this.
Ln 39-40 "Consequently, the detailed study of the stratigraphic succession of Cahuachi could be a climate proxy-record of particular interest" - unclear why this should be the case
Ln 42-43 See also:
Keefer, D.K., M.E. Moseley & S.D. DeFrance 2003. A 38 000-year record of floods and debris flows in the Ilo region of southern Peru and its relation to El Niño events and great earthquakes Palaeogeography, Palaeoclimatology, Palaeoecology 194: 41–77.
Ln 56ff "the data collected on the geological bedrock of Piramide Sur...shed light into the robustness or not of the Grodzicki’s thesis about the ENSO-related catastrophic river floods"
I have trouble following the logic here. Is the argument that if there were no pre-Cahuachi ENSO floods, then ENSO floods associated with terminal Cahuachi are unlikely? It's not clear to me how pre-Cahuachi deposits allow testing Grodzicki's proposition.
Ln 100 Reference to "'chala' life zone" needs a parenthetical definition and citation of Pulgar Vidal.
Ln108 "have repeatedly changed over south Peru during the late Quaternary"
This should read, “south coastal Peru" - the expansion and contraction of grasslands referenced is on the coast and the lower western slopes of the Andes, not over south Peru generally.
Ln 139-145
The most recent conglomerate was dated by 14C, I guess? What about the other two proposed ENSO-related conglomerates? How were they dated, and how do they relate stratigraphically to Cahuachi's construction? If the most recent conglomerate was dated by 14C to ca. 1000 AD, how can that be reconciled with this paper's conclusion that the conglomerates all predate Cahuachi?
Ln 150-153
This needs a bit more explanation. Judging by the photo (Fig 5) the 13 m vertically are stretched over at least 10m horizontally. So, they are exposed over a low hill, which was subsequently modified appear as a “piramide”? Why - in geomorphic terms - is there a hill here? The implication of Fig. 6 is that this is an erosional pedestal, in effect. Is that accurate? Some clarification that the Piramide Sur is in fact a modified hill would be important here as well.
Also, this suggests so far as I can tell that *all* of the stratigraphy discussed predates Cahuachi's construction (or at least this phase). In contrast, the deposits that Grodzicki discusses - used as the raison d'etre for this paper - all postdate Cahuachi's construction. That's not to say that examining these pre-Cahuachi sediments isn't useful and interesting, but why then focus so heavily on Grodzicki's proposals?
Fig. 6
Should include dates - if any are available, and if not why not? - and the construction described in the text (I think the suggestion is that all construction postdates these deposits, probably by millennia, but the lack of discussion of dating make this a bit vague).
Ln 368 Should read "pampa" rather than "palpa".
Author Response
You have kindly given the following comments and suggestions about our paper:
1) The analyses presented here are sound and clearly presented, but the framing of the paper renders the whole paper somewhat confusing. The focus on Grodzicki's proposals about ENSO-derived flood deposits accurately identifies an interesting question, but it's not clear that the evidence and analyses presented here are actually appropriate to address that question. Further, given the focus on Grodzicki's assertions, they are only minimally described - we don't know how the sediments he describes were dated, or how exactly they relate to those described here. Identifying those sediments, and/or ascertaining their relationships to those described here, seems fundamental, but is also barely addressed. The stratigraphic relationships and dates of the deposits - and archaeological features - concerned are critical to any interpretation, but they are barely discussed.
ANSWER: dear Reviewer, your comment highlight the need to describe in a more comprehensive way the Grodzicki’s proposals to better framing our paper. We have modified some parts of the manuscript to face your requests (see “track changes” in “Introduction”, “Material and Method” and “Discussion, summary and outlook”). We hope this will make our paper more readable.
NOTE: The three research items of Grodzicki, published from1990 to 1994, are “pioneering-works” (out of the current standard of scientific papers) and were aimed to the reconstruction of the late Holocene evolution of the Cahuachi area. It is not our intention to judge the quality of these works but it is evident how both the reconstruction of stratigraphic relationships and the use of some datings are rather subjective (we are dealing with these topic in detail in future researches at Cahuachi). Unfortunately, due to the lack of further geological studies on Cahuachi, the Grodzicki’s works have determined a paradigm later consolidated over time, quotation after quotation, without any discussion to his questionable interpretation.
2) The English is clear and comprehensible, particularly in the methods and results section, but the syntax should be reviewed by a native speaker.
ANSWER: we delegate this task to the editing service of MDPI.
Specific comments on the text:
Abstract
3) Lns 17 and 25 In the abstract (though not in the text) 'palpa' is used where 'pampa' is meant.
ANSWER: corrections made, thanks.
4) Ln 24 The ‘mainstream explanation' is that of two ENSO-related flood deposits at ca. 600 and 1000 AD? Unclear how a pre-Cahuachi (i.e. first millennium BCE) deposit should test this.
ANSWER: We are sorry for this misunderstanding. We report the pre-Cahuachi first century BCE in the section “Material and method” only to briefly describe the Grodzicki’s proposals. Here we test the third conglomerate indicated by this Author (see 171-172 lines with "track changes").
Main text
5) Ln 37 "This statement derives from an interpretative geological setting" - not clear what is meant by this.
ANSWER: We have made some changes in the text (please, see 38-44 lines).
6) Ln 39-40 "Consequently, the detailed study of the stratigraphic succession of Cahuachi could be a climate proxy-record of particular interest" - unclear why this should be the case
ANSWER: We hope that the changes made have cleared this point.
7) Ln 42-43 See also: Keefer, D.K., M.E. Moseley & S.D. DeFrance 2003. A 38 000-year record of floods and debris flows in the Ilo region of southern Peru and its relation to El Niño events and great earthquakes Palaeogeography, Palaeoclimatology, Palaeoecology 194: 41–77.
ANSWER: This reference has been considered and added in the References.
8) Ln 56ff "the data collected on the geological bedrock of Piramide Sur...shed light into the robustness or not of the Grodzicki’s thesis about the ENSO-related catastrophic river floods". I have trouble following the logic here. Is the argument that if there were no pre-Cahuachi ENSO floods, then ENSO floods associated with terminal Cahuachi are unlikely? It's not clear to me how pre-Cahuachi deposits allow testing Grodzicki's proposition.
ANSWER: We hope that the changes clarified this point.
9) Ln 100 Reference to "'chala' life zone" needs a parenthetical definition and citation of Pulgar Vidal.
ANSWER: The definition and the reference have been added.
10) Ln108 "have repeatedly changed over south Peru during the late Quaternary". This should read, “south coastal Peru" - the expansion and contraction of grasslands referenced is on the coast and the lower western slopes of the Andes, not over south Peru generally.
ANSWER: Many thanks for such a comments. The text is now corrected according to your comment (see 118-124 lines).
11) Ln 139-145. The most recent conglomerate was dated by 14C, I guess? What about the other two proposed ENSO-related conglomerates? How were they dated, and how do they relate stratigraphically to Cahuachi's construction? If the most recent conglomerate was dated by 14C to ca. 1000 AD, how can that be reconciled with this paper's conclusion that the conglomerates all predate Cahuachi?
ANSWER: Grodzicki has never dated the conglomerates with a scientific method (we are trying to date them during our future researches on Cahuachi). His statements only come from speculative interpretation of the relationship between the geological substratum and archaeological deposits containing organic material. As regards the conglomerate here discussed, the higher and younger, the attribution to 1000 CE come from guesswork-based correlations made by Grodzicki. However, according to this comment, the manuscript was modified (please, see 154-159 lines of the new version with “track changes”). We hope that the changes satisfy your requests.
12) Ln 150-153. This needs a bit more explanation. Judging by the photo (Fig 5) the 13 m vertically are stretched over at least 10m horizontally. So, they are exposed over a low hill, which was subsequently modified appear as a “piramide”? Why - in geomorphic terms - is there a hill here? The implication of Fig. 6 is that this is an erosional pedestal, in effect. Is that accurate? Some clarification that the Piramide Sur is in fact a modified hill would be important here as well.
ANSWER: Thanks you very much for this comment. A reference regarding the features of the “mounds-pyramids”, that characterize the archaeological site, is quite missing in the first version of the manuscript. We apology for our negligence. We have added a brief sentence (see 150-151 lines), referring to the basic-work of Orefici (2012) for every detail on the human adaptations of the morphology.
13) Also, this suggests so far as I can tell that *all* of the stratigraphy discussed predates Cahuachi's construction (or at least this phase). In contrast, the deposits that Grodzicki discusses - used as the raison d'etre for this paper - all postdate Cahuachi's construction. That's not to say that examining these pre-Cahuachi sediments isn't useful and interesting, but why then focus so heavily on Grodzicki's proposals?
ANSWER: In our view you are right. The whole succession here analysed clearly predate the construction of Cahuachi, belonging it to the transition from the Changuillo Fm to the Canete Fm (i.e. upper Pliocene-lower Pleistocene). Our correlation, made by lithostratigraphic and petrologic features, as exposed in the paper. Unfortunately, every attempt to date it on the basis on the fossiliferous content has failed (see 216-217 lines). At the moment we do not have the final proof, that is why the questioning character of the manuscript title. We are going to plan further analysis (e.g., OSL dating of sandy conglomerates and 39Ar-40Ar datings on tephra layers; see “5. Discussion, summary and outlook”). Again the latent problem is the speculative method (we believe) used by Grodzicki to date the section he studied.
14) Fig. 6. Should include dates - if any are available, and if not why not? - and the construction described in the text (I think the suggestion is that all construction postdates these deposits, probably by millennia, but the lack of discussion of dating make this a bit vague).
ANSWER: As reported above, datings are not available. It is known that the Changuillo-Canete transition is poor on fossils (see 104 lines) and also our micro-palaeontological tests failed (please, see 216-217 lines). Other dating methods will be used in the next steep of research (see 368-419 lines). However, to prevent any further misunderstanding, we have replaced the sentence of the first version: “the upper and younger conglomerate was identified on the Gran Piramide (Figure 4) and dated using fuel-remains placed at the top [Grodzicki, 1994]”, with a new sentence (see 155-157 lines of the new version with “track changes”) we hope less ambiguous.
15) Ln 368 Should read "pampa" rather than "palpa".
ANSWER: change made.
Reviewer 2 Report
This is a very interesting contribution to Nasca culture research. Although methods, concept and presentation are sound, I miss a significant contributing result. The presented research, therefore, remains preliminary. Further research on volcaniclastic layers and the dating of sediment layers is anounced, which will be very interesting for comparison with the regional context.
I highly recommend revision by a native English speaker. Further, I request more information on the characteristics of the adobe layer on top of the sediment sequence. Is it continous or fragmentary. Is there any evidence of how much of the sediment sequence was digged off? Concerning the volcaniclastic layer: is there any tephrochronological evidence in the region for that time frame?
Please check my remarks in the attached pdf.
Comments for author File: 
Comments.pdf
Author Response
You have kindly given the following comments and suggestions about our paper:
1) This is a very interesting contribution to Nasca culture research. Although methods, concept and presentation are sound, I miss a significant contributing result. The presented research, therefore, remains preliminary. Further research on volcaniclastic layers and the dating of sediment layers is anounced, which will be very interesting for comparison with the regional context.
ANSWER: The main issue of the paper is to test, for the first time, the Grodzicki thesis (see 54-68 lines with “track changes” option). Yes, our research is preliminary (please, see 25, 404, 420 lines).
2) I highly recommend revision by a native English speaker.
ANSWER: we delegate the English revision to the editing service of MDPI.
3) I request more information on the characteristics of the adobe layer on top of the sediment sequence. Is it continuous or fragmentary. Is there any evidence of how much of the sediment sequence was digged off?
ANSWER: the constructional features of the “Piramide Sur” temple are described by Orefici (2016) Recent discoveries in Cahuachi: the Templo Sur. In Ancient Nasca world. New insights from science and archaeology; Lasaponara, R.; Masini, N.; Orefici, G. Eds.; Springer: Basel, Switzerland, pp. 363–374. We have added a parenthetical sentence in the text.
4) Concerning the volcaniclastic layer: is there any tephrochronological evidence in the region for that time frame?
ANSWER: Ash layers (tuffaceous sandstones/siltstones) are present in the Changuillo and Cañete Formations. Their mineralogical, petrographic and geochemical studies will make possible tephrostratigraphic correlations with CH3 volcaniclastic layer and should contribute to better constrain the investigated section. In this framework, the methodological approaches of tephra fingerprinting as a tool for dating and correlate stratigraphic sections are given as an outlook in the last chapter of the revised manuscript. In particular, we are going to unravel chronostratigraphic correlations among the tephra layers (mostly using using 39Ar–40Ar datings of biotite microlites) referred to the Upper Barroso arc (between 3 and 1 Ma) as defined by Mamani et al. (2010), i.e. that Neogene magmatic activity in Southern Peru which is pertinent to the upper part of the Changuillo Formation and the Cañete Formation.
5) In an attached pdf, Reviewer 2 asked us to check several remarks.
ANSWER: the great part of the remarks concern the syntax of the paper have been integrated in the revised version (please, see "Track Changes" function). As regard you comment “I recommend only one spelling for Nazca/Nasca, maybe better the original one”, we recognize the problem, thanks you. In the first version we got confused. We have modified our manuscript trying to follow the more quoted use of the two words. Essentially, “Nasca” as regards the old civilization or consolidated terminology (as an example “Depresion of Ica-Nasca” in Earth Science); “Nazca” as regards the present town and its territory or the geographical domains (i.e. hydrograph basin”).
6) A main remark in the attached pdf concerns the final paragraph of the 2.1. section. The Reviewer has noted that our previous synthesis could have given “a wrong idea of how the landscape around Cahuachi was like”.
ANSWER: We made several changes in text according to the Reviewer’s comments (see 118-129 lines).
Reviewer 3 Report
This is a workmanlike, important paper testing a long-accepted hypothesis about the interaction between El Niño-derived flooding and abandonment of the Nasca capital of Cahuachi. I find the arguments convincing and well-supported by the detailed and well-illustrated analyses. I have only a few minor suggestions for revision.
First, the authors imply (lines 56-61 "...and other pre-Columbian sites") that a strong argument against the Grodzicki hypothesis also devalues similar hypotheses about other archaeological sites along the Peruvian coast. Perhaps this was unintentional, but I urge the authors to be clear that each case requires the kind of analysis they have done for Cahuachi. Actualistic observations and historical records make it abundantly clear that El Niño floods do occur and can be highly destructive, so they can only be discounted in human eco-dynamical hypotheses through detailed on-site study.
Second, the study would have been improved by chronometric dating of their section, especially the part that underlies the pyramid. Dating of the section is possible if not highly accurate using OSL. The authors might point to use of OSL as one of the next steps to continue the research.
Third (lines 353-359): The authors argue against an ENSO origin for the sandy conglomerate at the top of their section because that conglomerate is similar to two earlier versions that are presumably much older. What can't all three be the result of ENSO flooding? The paper would be strengthened by describing an idealized El Niño flood signature (drawing, for instance, on Lisa Well's 1990 paper in Geology) and comparing that to the sandy conglomerate.
Author Response
You have kindly given the following comments and suggestions about our paper:
1) This is a workmanlike, important paper testing a long-accepted hypothesis about the interaction between El Niño-derived flooding and abandonment of the Nasca capital of Cahuachi. I find the arguments convincing and well-supported by the detailed and well-illustrated analyses. I have only a few minor suggestions for revision. First, the authors imply (lines 56-61 "...and other pre-Columbian sites") that a strong argument against the Grodzicki hypothesis also devalues similar hypotheses about other archaeological sites along the Peruvian coast. Perhaps this was unintentional, but I urge the authors to be clear that each case requires the kind of analysis they have done for Cahuachi. Actualistic observations and historical records make it abundantly clear that El Niño floods do occur and can be highly destructive, so they can only be discounted in human eco-dynamical hypotheses through detailed on-site study.
ANSWER: We apologize for this misunderstanding that is quite unintentional. We have corrected the sentences (please, see 66-68 with “track changes” option).
2) Second, the study would have been improved by chronometric dating of their section, especially the part that underlies the pyramid. Dating of the section is possible if not highly accurate using OSL. The authors might point to use of OSL as one of the next steps to continue the research.
ANSWER: We have specified the outlook in the chapter 5 also including OSL. Thanks.
3) Third (lines 353-359): The authors argue against an ENSO origin for the sandy conglomerate at the top of their section because that conglomerate is similar to two earlier versions that are presumably much older. What can't all three be the result of ENSO flooding? The paper would be strengthened by describing an idealized El Niño flood signature (drawing, for instance, on Lisa Well's 1990 paper in Geology) and comparing that to the sandy conglomerate.
ANSWER: We accepted your suggestion, thus we underline the issue in the paper (398-400 lines) and we take note for the next goals.
Round 2
Reviewer 1 Report
The authors have thoroughly addressed my concerns, and I recommend that the revised ms. be published. The text could still benefit from copy editing by a native English speaker.
Reviewer 2 Report
Dear authors,
this is an important and interesting contribution to Nasca culture research. I thank you for addressing my suggestions to improve the language and for providing all requested information!
