Vegetation, Climate and Habitability in the Marseille Basin (SE France) circa 1 Ma

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

(1) Where are the figures for this study? Also not found in the attachment.

(2) What are the advantages of the location of the research site in responding to climate and environmental change processes?

(3) How many meters is the sampling profile?

(4) What is the storage method for different samples after collection?

(5) Insufficient details in carbon and oxygen stable isotope testing analysis compared to pollen analysis

(6) I got lost in "Pollen informed climate reconstructions" because the modern data used for climate reconstruction seems to have no explanation. In addition, climate reconstruction spanning millions of years is difficult to sustain solely by relying on pollen, so I suggest using isotope data together.

Author Response

Reviewer one

• Where are the figures for this study? Also not found in the attachment.

Sorry, the first version had the figures in a separated file. Now they are integrated in the Geosciences template version.

• What are the advantages of the location of the research site in responding to climate and environmental change processes?

Our paper is not really focused on climate and environmental change, but more to describe the environment present about 1 Ma ago in a place to be settle by the first hominins. Indeed we do not have enough paleoenvironmental data (especially pollen bearing samples) to built a time sequence. We feel our research site is located in a key place for our task: along the southern European sea coast and the migration route of hominins from middle East to Spain, with specific resource (travertine springs) in a dry environment.

• How many meters is the sampling profile?

We sampled 3 profiles, but the longest and only continuous one (Plan d’Aou) that served for the magnetostratigraphy (Fig.7) is 9.5 m, as appears in the figure.

• What is the storage method for different samples after collection?

Collected samples are rocks, stored in sealed plastic bags. We took care of avoiding present day pollen pollution by cutting with water the initially sampled blocks to get rid of the weathered and exposed surface and store the clean sawn blocks in new plastic bags after drying at 40°C. This was exposed in the text.

• Insufficient details in carbon and oxygen stable isotope testing analysis compared to pollen analysis

Additionnal information has been supplied on sample number and location. The location of sampled sections has been reported on Figure 1. The methods section has 7 lines describing the measurement methods.

• I got lost in "Pollen informed climate reconstructions" because the modern data used for climate reconstruction seems to have no explanation. In addition, climate reconstruction spanning millions of years is difficult to sustain solely by relying on pollen, so I suggest using isotope data together.

The paragraph describing the different climate reconstruction methods has been slightly modified for better understanding. However, this is not a methodology article and we cannot re-explain the methods, which have already been published many times.

In the discussion, we have added a sentence to link isotope data and pollen-based climate reconstruction: “The reconstructed climate at Marseille shows a cooler climate, mainly during winter, and wetter conditions compared to modern values (Figure 16). The reconstructed temperatures based on pollen data are in agreement with the very negative of δ¹³C values reconstructed consistent with a calcareous tufa that formed in cool water”.

Moreover, as stated above we do not have the data necessary to present a climate change style paper (proxies versus time with large number of samples regularly placed in a sequence). We just offer an image of the environment of the place one Ma ago, with some hints at its variability. In the discussion, we compared the climatic data delivered by the Marseille tufa with nearby sites, and the results seems to be coherent. We still feel this approach is valuable.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

I like your paper.

This paper is very interesting because of two reasons already mentioned in the paper:

·         Tufa is considered as poor material for pollen preservation.

·         The study of Pleistocene tufa within the Marseille basin, has been neglected since early research and no new paleontological data have been acquired since the end of the 19th century.

It is also important because of the record of proto-cereal pollen and the explanation that there could be a habitat for hominins when they arrived there about 1 Ma ago.

My suggestions (marked also on the attached manuscript) are:

1.       I don’t see Keywords. Why?

2.       Why sedimentological analysis has been performed only on three localities?

3.       Why do you say that Mediterranean pine pollen includes Pinus grains > 63 mm long? What species?

4.       Please, add a few sentences about “mean Pollen Sum (PS)” in Methods. What do you mean when you say pollen concentration? Only pollen or? Do you count charcoal in pollen? Maybe you can use the word sporomorph or palynomorph instead of pollen when you count all of them.

5.       Write the full name of Type 200. Is this NPP? HdV-200?

6.       Can you be more specific when you mention Chrysophyceae? Genus?

7.       Some sentences need a short explanation: for people who are not experts in your field of research, it is important to know how and why you interpret your data. Please, add

8.       Some sentences are not clear to me. Maybe you can correct them. On page 12: “The pollen assemblage of sample 7, whose stratigraphic position is just below the tufa with an unknown age control (although assumed to be Pleistocene) is rather consistent with that of the tufa samples.”

9.       Paper would benefit from slight changes in the text's structure. For example, some parts from the Introduction (page 3, where you explain your opinion) could be moved to the Discussion.

10.   References are better to omit in the Conclusion.

11.   Please check the Author Contributions. What about Belinda Gambin and De Coignac Samuel Benoît?

12.   Please check the references. Some of them are missing, and some of them are wrong.

13.   For minor comments please see notes on the attached manuscript.

14.   I cannot see St Barnabé-Les Olives, Fondacle and La Valentine in Fig.1.

15.   Where is the Nord in Fig. 9?

16.   Charcoal is better to move to the end in Supplementary File S2, not alphabetically all forms together.

 

17.   Please add references to Supplementary File S6.

Comments for author File: Comments.pdf

Author Response

Reviewer two

Dear Authors,

I like your paper.

This paper is very interesting because of two reasons already mentioned in the paper:

• Tufa is considered as poor material for pollen preservation.
• The study of Pleistocene tufa within the Marseille basin, has been neglected since early research and no new paleontological data have been acquired since the end of the 19th century.

It is also important because of the record of proto-cereal pollen and the explanation that there could be a habitat for hominins when they arrived there about 1 Ma ago.

My suggestions (marked also on the attached manuscript) are:

1. I don’t see Keywords. Why?

Present in the new version (template of the article) : Marseille France, Early Pleistocene, vegetation, potential diet, cereals, climate, depositional environment

 

2. Why sedimentological analysis has been performed only on three localities?

We studied the three localities that revealed 4 out of 6 pollen bearing tufa samples. We feel it is enough to understand the local variabilities in tufa deposits. The two other tufa sites (Olives quarry and Amarillys) are hard to access (remember that all sites are inside a large city), but our field work revealed similar features with the ones observed in the three reported localities. We state it in the text now. Note that the marly site of les Olives avenue is no longer accessible (it was sampled in the foundations of a building).

3. Why do you say that Mediterranean pine pollen includes Pinus grains > 63 mm long? What species?

Because Mediterranean pine pollen are big pollen, cf Reille 1992*. This morphotype can include many Mediterranean pines growing presently in Mediterranean as Pinus maritima, P. pinaster or P. pinea. P. halepensis is also a big pollen that can be identified to the species level thanks to « the presence of a marginal ridge on either side of the proximal thickness of the Pinus grain in equatorial view” as indicated in our article.

Below, the changes we made in the article:

Mediterranean pine pollen includes Pinus grains > 63 mm long as Pinus maritima, P. pinaster or P. pinea.

*Reille, M. Pollen et spores d’Europe et d’Afrique du Nord. Laboratoire de Botanique Historique et de Palynologie, 1992.

4. Please, add a few sentences about “mean Pollen Sum (PS)” in Methods. What do you mean when you say pollen concentration? Only pollen or? Do you count charcoal in pollen? Maybe you can use the word sporomorph or palynomorph instead of pollen when you count all of them.

Re-written in the article, cf below :

« Spores and NPPs have been excluded from the Pollen Sum (PS) for the calculation of relative frequencies. In this case, the mean PS is of 117 grains per sample. When spores and NPPs are included, the mean PS per sample is of 27,096. »

5. Write the full name of Type 200. Is this NPP? HdV-200?

Type 200 is a NPP proposed by Van Geel (1998)*

* van Geel B (1978) A palaeoecological study of Holocene peat bog sections in Germany and The Netherlands, based on the analysisof pollen, spores and macro- and microscopic remains of fungi,algae, cormophytes and animals. Rev Palaeobot Palynol 25:1–120

6. Can you be more specific when you mention Chrysophyceae? Genus?

When fossilized and after chemical treatment of the samples, Chrysophyceae cysts lose their morphological specificity and it is unfortunately not possible to identify them to species level.

7. Some sentences need a short explanation: for people who are not experts in your field of research, it is important to know how and why you interpret your data. Please, add

We hope the additions in new version will respond to this.

8. Some sentences are not clear to me. Maybe you can correct them. On page 12: “The pollen assemblage of sample 7, whose stratigraphic position is just below the tufa with an unknown age control (although assumed to be Pleistocene) is rather consistent with that of the tufa samples.”

We agree. We changed the sentence. The revised sentence is: « The stratigraphic position of sample 7 is just below the tufa with an unknown age control (although assumed to be Pleistocene). As the pollen assemblage of this sample is consistent with the six tufa pollen samples, we consider that sample 7 is contemporary with the deposition of the Marseille tufa.”

9. Paper would benefit from slight changes in the text's structure. For example, some parts from the Introduction (page 3, where you explain your opinion) could be moved to the Discussion.

We agree. We removed from the article the discussion sentences present in the introduction. We didn't think it was necessary to make a paragraph of it in the discussion. The eliminated sentences are: « We agree with this hypothesis, because the morphology of L. nobilis and L. canariensis is very close and, nowadays, L. nobilis is present in the French Mediterranean flora. The same questioning concerns Trachycarpus, a palm from the Far East that has a form very close to that of Chamaerops humilis whose distribution is western Mediterranean. The presence of Chamaerops humilis in the Marseille tufa seems more likely. However, we cannot decide whether Magnolia was present during the Early Pleistocene in W. Europe [23]. Its presence would be singular because the present-day distribution of Magnolia is mainly humid tropical regions of E. and S. Asia, and all of America.”

10. References are better to omit in the Conclusion.

Removed in the revised version.

11. Please check the Author Contributions. What about Belinda Gambin and De Coignac Samuel Benoît?

Done in the revised version.

12. Please check the references. Some of them are missing, and some of them are wrong.

The reference numbering and correspondence between text and list have been carefully checked and revised in the new version.

13. For minor comments please see notes on the attached manuscript.

£ Note p. 13 of the reviewer 2 manuscript: «May be reversal of sediment » related to the sentence : «The stratigraphic position of sample 7 is just below the tufa with an unknown age control (although assumed to be Pleistocene). As the pollen assemblage of this sample is consistent with the six tufa pollen samples, we consider that sample 7 is contemporary with the deposition of the Marseille tufa.”. No stratigraphic inversion has been revealed in the Pleistocene tufa of the Marseille Basin according to previous structural studies (Dupire, 1985) : the entire regional Quaternary sedimentary series is in normal stratigraphic position, post-dating the main phases of regional tectonic deformation.

£ P 14 of the reviewer 2 manuscript: « 6% of SP » changed in PS = Pollen Sum

£ P 17 of the reviewer 2 manuscript: « In total, 82 edible taxa were identified (Supplementary File S7) based on our knowledge research carried out in Andrieu-Ponel et al. [5], as well as the bibliography [86-88]. The revised version is : « In total, 82 edible taxa were identified (Supplementary File S7) based on our knowledge [5], and those found in the litterature [86-88].”

£ P18 of the reviewer 2 manuscript: “The discovery of micro-charcoals in ancient natural (and non-archaeological) sites that we study within the framework”. Rewiever 2 ask: “which site?”. This is at the end of the sentence (underlined): “The discovery of micro-charcoals in ancient natural (and non-archaeological) site that we study within the framework of the ANR FOOD-RE indicates the existence of fires, natural or not, in the lake series of SW Turkey, Acıgöl and Burdur until more than 3 Ma.”

£ P 20 of the reviewer 2 manuscript: “Previous studies date back to the end of the 19th century and the beginning of the 20th century with the pioneering work of [13]”. OK, those last words removed in the revised version.

14. I cannot see St Barnabé-Les Olives, Fondacle and La Valentine in Fig.1.

We removed St Barnabé and Fondacle which are secondary names on the selected sites. La Valentine is present in Fig.1.

15. Where is the Nord in Fig. 9?

Although the diagram is essentially conceptual (and not necessarily directional), we can nevertheless consider that the majority of springs and streams originate from the Etoile Massif located to the north of the Marseille Basin (see Figure 1 for location). A north polarity has thus been integrated accordingly in Figure 9.

16. Charcoal is better to move to the end in Supplementary File S2, not alphabetically all forms together.

The charcoal microparticles are part of the pollen assemblages, as are the NPPs. For the sake of simplicity, it seems preferable to leave the charcoals microparticles in alphabetical order of the palynomorphs and NPPs identified in the assemblages.

17. Please add references to Supplementary File S6.

We do not add references because the ecological groupings we use rely on general knowledge of ecology and do not refer to a specific article.

Reviewer 3 Report

Comments and Suggestions for Authors

This paper is an interesting topic and I really like the interdisciplinary approach. There are a few comments: Page 3, line 10: plateau is 10-20 m thick? express better; page 4: what is shallow environment? Shallow marine, ponds....: what is the lowerest point in the basin?; missing references to a brief description of the geology; page 5: what is a large sample?; page 6: sedimentological analyses: more on the criteria used for the depositional model, some more data on classification (terms rudstones....); page 8: explain better the relationship between paleohydrological data and stable isotopes of O and C.  Missing in the discussions is the interpolation of data from stable isotopes, paleomagnetism. The discussion only focuses on pollen data and a little on sedimentology. I think including own data in discussin all facts can be better proven.

Author Response

Reviewer three

This paper is an interesting topic and I really like the interdisciplinary approach. There are a few comments:

Page 3, line 10: plateau is 10-20 m thick? express better;

As the tufa plateau of Marseille was formed in a fluviatile environment with varying position of streams and channels, the thickness of tufa deposits is laterally variable. In addition, thickness variation of tufa formation is also caused by post-depositional erosion processes. We change the sentence to “plateau is 10 to 20 m thick”

Page 4: what is shallow environment? Shallow marine, ponds....: what is the lowerest point in the basin?; missing references to a brief description of the geology;

Here it means shallow-water, marginal lacustrine environment. To avoid redundancy, the sentence has been changed as follows: « It was deposited in a varied (fluvial, lacustrine, encrusting waterfalls) continental depositional environment »

Page 5: what is a large sample?;

We precise in the new version : « 23 large samples of about one cubic decimeter were taken in these 7 sites”

Page 6: sedimentological analyses: more on the criteria used for the depositional model, some more data on classification (terms rudstones....);

The sentence has been modified as follows:

« The depositional facies of the calcareous tufa have been classified using a continental carbonates facies nomenclature [28] which is based on the depositional texture, grain size and the nature of dominant carbonate components such as phytoclasts, skeletal bioclasts, concoids and peloids. »

Page 8: explain better the relationship between paleohydrological data and stable isotopes of O and C.  Missing in the discussions is the interpolation of data from stable isotopes, paleomagnetism. The discussion only focuses on pollen data and a little on sedimentology. I think including own data in discussin all facts can be better proven.

As stated above we do not provide temporal sequence, e.g. stable isotope curves versus depth or age, so we do not clearly see what could be added. The main focus of our paper and its discussion is the paleodiet accessible to the hominins in Marseille basin. Paleomagnetic interpretation is done in the results section; it seems more appropriate to us to restrict the discussion to vegetation, climatic, habitability and environmental issues.

Regarding C and O isotopes, as clearly indicated in section 4.2, the results have been used essentially to demonstrate that the calcareous tufas were formed from ambient temperature water and not from hot, hydrothermal water, indicating therefore that they are not travertines.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

This study has rich field investigations, solid experimental work, and rigorous graphic and textual materials. Therefore, it is worth publishing.

Author Response

Dear reviewer, thanks for your appreciation