Sunday, November 22, 2020

The Geography of Partheni Bay on Leros

 

The island of Leros, in the Dodecanese, lies between Patmos and Kalymnos. 


Leros is situated between Patmos and Kalymnos

 Simpson and Dickinson tell of an early Bronze Age site discovered on the edge of Partheni Bay which is in the north of Leros as shown on the next map.  


Partheni Bay on Leros

  Simpson and Dickinson characterize the site like this:

"The easternmost of three promontories (collectively named "Ta Poundaria") on the S shore of Partheni Bay in the N of the island was an EB settlement.  The site is only 80 m. NNW-SSE by 40 m., but may have been partly eroded by the sea.  The  sherds found are from jars and pithoi of EB I type.  ... "[1]

Where exactly is this site?


Partheni Bay on Leros with ta Poundaria labelled.



On this map we see the three promontories called 'ta Poundaria'. They are the easternmost on the south coast of Partheni Bay. The one furthest E I have arbitrarily labelled "Poundaria 1". Its neighbors,Ta Poundaria 2 and 3, lie just to its W.

Let's look at Ta Poundaria 1 in closeup:




Does this satisfy the criteria set out by our authors? Here's what Simpson and Lazenby said about it earlier:

" ... a very low and very small promontory ... with the remains of an L-shaped mole at its north-west tip. The promontory, which is about 80 m. long by 40 m. wide, is the easternmost of the three (named collectively 'Ta Poundaria') in the middle of the south shore of Partheni Bay (the central promontory is even smaller, and the westernmost is the peninsula discussed by Benson where both Ross and Burchner reported tholaria)."(52)[2]

Here Simpson and Lazenby are, confusingly, giving the size of the peninsula as 40 x 80 m. when, in fact, it's the site that's 40 x 80 m.[3] The hypothesized size of the site is thus 3200 m. The actual area of this peninsula is about 29,700 sq. m.

In order to give an idea of the size of the site relative to the peninsula I have drawn a circle with an area of 3200 m. (about 32 m. radius) against a photo of Ta Poundaria 1. I show this circle in the next photo:


Ta Poundaria 1 with a circle sized to approximately the dimensions of the site.

I have identifies this site in the Mycenaean Atlas Project as C7111 and I suppose that we're no more than twenty or so meters away from wherever it was that these Early Bronze sherds were discovered.

A Second Site, C7112


Simpson and Dickinson [1979] 367 suggest the presence of another site in this area:

"Similar fragments of pithoi found on a hillock c. 1 km. to SW may  represent  a cemetery area connected with the settlement.'"[4]

Where is this 'hillock'?  




The hillock in question sits just to the SW of the Leros airport runway.  At its highest point it is 11 m. above the surrounding plain.  On its peak sit the ruins of a tower about 8m square, presumably Hellenistic, and about which there has been some debate.  Early investigators supposed it to be the site of the often-mentioned Temple to Artemis (Parthenos Iokallis).  The virgin Iokallis has been thought to be a local semi-deity whose cult was assimilated to that of Artemis.  In 1905 Dawkins and Wace established that this platform was really just a tower.[5]  Bean and Cook reaffirmed this in 1957.[6]  And even though no other location for the temple has been suggested, this remains the consensus of scholars today.  But the idea that Artemis' temple is located on this hill hasn't quite died.   (Including the Greek Ministry of Culture and Sports which still has this claim on their website here. )  In fact, Benson gives reasons why the tower base may have originally been the location of a small temple.  

Here's a photo of the entire top of the hill with some superimposed drawings of what can be made of the structures currently remaining.


The green cylinders (T1, ... ) are trees: a crude if effective way of representing them.  S1 and S2 are structures whose purpose I cannot determine.  The structure labelled 'Platform' is the proposed tower base.  The orange structure labelled 'Nave' is the location of the church of H. Eirene. I marked one structure, in yellow, with a question mark.  It is not clear whether or not this is part of H. Eirene.

Following is a photograph of the same area from directly above:




At some point in the Christian era the stones of the tower platform were re-used to build a small chapel to H. Eirene (F6216). [7]   Of H. Eirene Benson says this:

"Parallel and very near the tower on its north side is a small ruined chapel , known locally as Ayia Eirene, built largely with blocks taken from the tower. The small conch - like apse is constructed of brick and concrete , which was covered with plaster on which are traces of wall painting in red, yellow and dark greenish grey paint. The total height of the apse above the present surface is 2.45 m. A clandestine excavation which had taken place recently went down below the obvious level for a floor without revealing any traces of one."[8]

I found some pictures that show what remains of the nave of this chapel.  You should be able to link to them here: 
https://www.lerosinfo.com/media/k2/items/cache/954fb0ebf1d84fb921bfb0b6e045d57f_XL.jpg




This is the same scene from the photograph looking down the 'nave' of H. Eirene facing east.   Next to it on the S (right) is what's left of the tower platform.    On the N (left) of the chapel is a low yellow structure.  Photographs indicate that the slope falls away towards the N and I could not interpret what this structure was.  Take it with a grain of salt.

As for the platform itself there is another user-contributed photo that shows it up close and looking W.  You can find that photo here: https://media-cdn.tripadvisor.com/media/photo-m/1280/18/7c/ac/ae/view-of-temple-of-artemis.jpg

Here is a reproduction of that photo.  Here the viewer is looking directly W along the apse end of the nave (center).  The platform is to the S (on the left) under the shade of a tree.  


The temple that was thought to be here was famous in antiquity as sacred to Artemis.  The priests kept Guinea hens here which they advertised as Meleager's sisters, the Meleagrides.

In my next post I will devote more space to the myth of Meleager.


Footnotes



[1] Simpson and Dickinson [1979] 367, 'Partheni: Ta Poundaria etc.'.

[2] Simpson and Lazenby [1970] 52, 'Leros; Partheni'

[3] Simpson and Dickinson [1979] ibid.

[4] Idem.

[5] Dawkins and Wace [1905] But see Benson [1963] 16,  ' ... this may be the site of the Temple of the Parthenos, if it was of modest proportions.' 

[6] Bean and Cook [1957] 134, 'Leros': " ...; and at H. Eirene, between the bay and H. Georgios, is the ruin of a square tower described and illlustrated by Dawkins and Wace."

[7] The name confirmed in Benson [1963] 17 and n. 48.

[8] Benson [1963] 17.



Biblio

Bean and Cook [1957] : G.E. Bean and J.M. Cook, 'The Carian Coast III', Annual of the British School at Athens (52) 'Leros', pp. 58-146. [1957]. Especially 134 ff. It is online here.

Benson [1963]:  Benson Ancient Leros. Duke University, Durham, North Carolina and Eaton Press, Mass., U.S.A. 1963. Online here.

Dawkins and Wace [1905] : Dawkins, R.M. and Alan J.B. Wace, 'Notes from the Sporades, Astypalaea, Telos, Nisyros, Leros', Annual of the British School at Athens (12) 151-174, [1905-06]. esp. Section '4 - Leros', which starts on 172.  They include a photo of the base of the tower taken facing approx. W. It is online here:

Simpson and Dickinson [1979] : Simpson, Richard Hope and O.T.P.K. Dickinson. A Gazetteer of Aegean Civilization in the Bronze Age, Vol. I: The Mainland and the Islands. Paul Åströms Förlag, Goteborg. 1979., 'Partheni: Ta Poundaria etc.', pg. 367. Online here :

Simpson and Lazenby [1970] : Simpson, R. Hope and J.F. Lazenby. 'Notes from the Dodecanese II', The Annual of the British School at Athens (65). pp. 47-77. 1970. Online here:

Saturday, June 20, 2020

Starochorafa on Kefalonia (C588)

The island of Kephalonia lies just off the west coast of Greece and directly facing the entrance to the Gulf of Corinth as is plain from this map. 




One of the best resources for Kephalonia as well as the Ionian islands in general can be found in the books and articles of Dr. Christina Souyoudzoglou-Haywood.   I've listed some of her writings in the bibliography at the end of this post.   

In this next map we see Kefalonia in close-up as it appears in the Mycenaean Atlas Project.  The blue paddles are specific sites and the red paddles (marked 'F') are modern-day features.

The island of Kephalonia


I've been reading an  article by her, ''Interpreting the Bronze Age Landscape of Kephalonia. A (Preliminary) View from the Livatho Valley Survey' in which she mentions a site near Argostoli, called Starochorafa.[1]  Starochorafa is mentioned in Simpson [1981] 156 as 'a locality named Starochorafa, three walls of a Mycenaean house were uncovered ... '. And ' ... only a few Mycenaean sherds were found, together with coarse ware, also presumably Mycenaean.'   It turns out that Starochorafa is one of the few places in the Ionian islands where true Mycenaean finds can be found and it has a little history.  It was originally  discovered by Marinatos (published 1932, AE [1932] 14, 42 n. 2) and then 'lost' until the Livatha Valley Survey Project stumbled across it again in 2007.

So where is Starochorafa?   I actually included this site in the Mycenaean Atlas long ago as site C588, based purely on Simpson who gives few clues as to its actual whereabouts.  Originally I put it here: 38.160442° N, 20.534861° E.  But now I have been able to glean some new information and I have learned that its real location is about 800 m distant to the SW.  It's actually here:  38.158419° N, 20.526261° E.

How was this more accurate location determined?

In the article mentioned above Dr. Souyoudzoglou-Haywood presents a photograph which I never noticed before of two archaeological field workers collecting surface sherds at Starochorafa[2].  I reproduce it here:


Where is this open field?  Which way  are we facing?  What is the ridge in the background?  We are not told.  Let's see whether we can figure this out by trying to reproduce it somehow in Google Earth.  Is there even a starting point?  I used Dr. Souyoudzoglou-Haywood's map of the survey area which I reproduce here:[3]



This map shows twenty-six Bronze Age find spots discovered by the LSV survey project.  I  plotted each of these on Google Earth.  The result was this:


The points closest to my original Starochorafa were points 10-13.  I blow them up here.  [Keph_Overlay_Detail.jpg]


Could these be the 'real' Starochorafa.  I zoomed in on this area on Google Earth and almost immediately hit paydirt.  Here's what this area looks like in close-up:




I found the grassy field between points 10 and 12 a real possibility for place from which the photograph was taken.  I zoomed into that field and tried to reproduce the same view.  The result is this:


And here, again, is the original  photo of Dr. Souyoudzoglou-Haywood so that you can compare it:



When we put these two pictures together we see that they are entirely consistent with each other.  Examination of the skyline shows that the positions are very likely to be the same.  It was here that I placed the marker.  It turns out that Starochorafa is more complex and extended.  Dr. S.-H. has put four different markers, placed closely together which encompass various components of Starochorafa.  But this picture at least gets us started and it's a huge improvement on what I had before.  I'll be releasing a new database soon and it will have the corrected position on it.

As usual I want everyone to stay safe.  COVID-19 is not the flu.  It is a dangerous viral infection - but you don't need to be told that by now.  Social distance and use masks when you go out of your homes.  I need all the readers I can get.

And ... friends don't let friends use Facebook.

NOTES

[1] Souyoudzoglou-Haywood [2008] 241.  "‘Starochorafa’ ... is largely a one period site of Mycenaean date (LH III, most likely LHIIIC only). It is one of the two small settlements mentioned above which were excavated by Marinatos ... The toponym fell into disuse over time, and the site was only identified anew during the 2007 fieldwork season.  Marinatos ... only excavated part of one house (6.80m x 4.20m), and reported that, having been prevented from continuing the excavation in a neighbouring field, he covered up the exposed remains of the site at the end of his brief campaign."

[2] Souyoudzoglou-Haywood [2008] 243, fig. 4.

[3] Souyoudzoglou-Haywood [2008] 240, fig. 2.

BIBLIO

Haywood [2018]:  Haywood, Christina.  'Archaeology and the Search for Homeric Ithaca: The Case of Mycenaean Kephalonia', Acta Archaeologica [89:1] 145-158.  2018.  Abstract is online here.

Livatha Survey Project:  The homepage of the Kephalonia - Livatho Valley Survey project is here.

Morgan [2007]:   Morgan, Catherine. Archaeological Reports (54) p. 46,  'Livatho Valley Survey'.   2007-2008.  Online here.

Simpson [1981]: Simpson, Richard Hope.  Mycenaean Greece. Noyes Press, Park Ridge, New Jersey.  1981.

Simpson [2018]: Simpson, Richard Hope.  Mycenaean Greece and the Homeric Tradition.  This book may be downloaded from here.

Souyoudzoglou-Haywood, Christina.  'A Corner of the Landscape: The Kefalonia  Project 2001-02.  A Preliminary Account', on JSTOR here.

Souyoudzoglou-Haywood [2008]:   Cristina Souyoudzoglou-Haywood, 'Interpreting the Bronze Age Landscape of Kephalonia. A (Preliminary) View from the Livatho Valley Survey'. 
In: C. Gallou, Georgiadis, and Muskett (edd.), Dioskouroi: Studies Presented to W.G. Cavanagh and C.B. Mee on the Anniversary of their 30-year Joint Contribution to Aegean Archaeology (BAR IS-1889) Oxford: Archaeopress, 237-251.  The paper is online here.

Wednesday, April 15, 2020

Metsiphi (C6878)




The area of Euboea south of Styra is a wild forested country of zig-zagging ridges.  It was not densely populated at any period in antiquity and it remains sparsely populated today.    I've been adding find sites in this area to the Mycenaean Atlas by integrating Fachard [2012] and this brought me to an habitation site called Metsiphi.

The site of Metsiphi (no. 4 on the next map) consists of a six-room building and a boundary stone marking the border between the demes of Eretria and Styra.  It may be a construction of either the Archaic or the Classical period.






Where is it?

I was able to locate two sets of directions to this site.  The map above should help you in following them.  And, in order to make better sense out of the geography I include some place name definitions (marked with an asterisk in this text, thus Kiapha Pass*) in a glossary appended to this post.

Fachard [2012] gives these directions to Metsiphi:

From the Kiapha* pass, located some 300 m north of the gate of the Venetian castle of Larmena*, you can follow an (ancient?) path towards the valley of Aghios Ioannis. About 1 km east of the pass, there is an old building and a rock monument, both discovered by N. K. Moutsopoulos.”(1)


The town of Styra, in southern Euboea, lies just to the north of a long mountainous ridge (Kliosi*) that runs north-east to south-west across the entire length of the island. There is a classical period fort (sometimes referred to as the Acropolis of Styra*, F5701) on this ridge and immediately to its east the Venetian castle of Larmena*(Armena*, F5654).   That would put the pass (col) at F5694 where there does indeed appear to be a saddle over the ridge of Haghios Nikolaos. In Google Earth I drew a circle of 1000 m. radius and centered it on this pass.  But without any specific thing to look for the chances of seeing an overgrown ruin in GE are basically zero. And, as for the toponym of 'Haghios Ioannis', it is undiscoverable on any map to which I have access.

What to do?



I found another source which gives directions to Metsiphi. In Reber [2002] we read the following:

"In antiquity, two different routes led from Styra to Karystos. One corresponded roughly to the course of today's road, the other led first from Styra to the east and then followed the gentle slope of the northern slope of the Kliosi*. Via a saddle east of the fortifications one first came into a gorge and from there via a low saddle into the wide valley of Stoupaioi. From Stoupaioi, the path led through the mountains to the south, where it merged with the first path behind the village of Vatisi."(2)

Then he remarks:

"If you follow the path to Stoupaioi, which is partly paved with ancient retaining walls, you will find the ruins of an ancient building, which was uncovered by N.K. Moutsopoulos, below the saddle at Metsiphi." (3)


Karystos itself is at the south end of Euboea (F5697).  Kliosi* is another name for the ridge on which stands the Acropolis of Styra* (F5654).  Stoupaioi is at F5695 and Vatisi is further south at F5696.  And yet we still have no definite narrowing for the location of Metsiphi.  

But as Reber does not specify the starting point these directions do not help. Are we starting from Styra again? From the col (Sattel)?  Just as Reder promised to get specific he starts referring generally to ‘the path to Stoupaioi’. This path is a long one and through wild country; it will not help us to find Metsiphi.

What to do?

Well, it turns out that Reber does provide a photograph of the Metsiphi house in question. Perhaps it’s possible to duplicate that view in Google Earth. Here’s the picture: (4)


The house at Metsiphi.  But which direction are we facing?
I looked at this for a while and I decided that if it were possible to identify the mountain in the background it might be possible to draw a line back from that mountain to the site of Metsiphi.  At this point I really had no hope of locating Metsiphi exactly.

Could this view be replicated in Google Earth?  On my first attempt I came up with this:



It was gratifying to come so close on the first attempt.  It turns out that the  background mountain in this picture is Peristeri (F5693).   But it was clear that I hadn't yet succeeded in finding Metsiphi.  In Reber's original there is a ridge in the right center which is of lighter color than its surroundings.  That ridge does not appear in my reconstruction.  I continued to rotate the image in Google Earth until I had this:



In this view 1  indicates the pale colored slope which appears also in Reber's picture.  2 is the Peristeri peak. 3 indicates the slope down from the left which is also in Reber's picture.

We're obviously very close to Metsiphi at this point.  Can we find it by searching around this point?  Not likely, but first let's see what we're looking for.  Here's the floor plan of this building as supplied by Reber:

Floor plan of Metsiphi house from Reber [2002] 46, Abb. 3.

I started to search in this area and in no time I found this:



And zooming in:




In this version I did a find-edges in Photoshop and then multiplied it against the picture layer.  To say that I was astonished when I saw that grid shape is an understatement.  This is a difficult country.  I'd been looking for an entire day with absolutely no expectation of finding the exact site but suddenly there it was.

And one last mystery to clear up:  What or where is the valley of Aghios Ioannis?

The valley of Aghios Ioannis is just the light-colored ridge which appears at the right center of Reber's original photograph.  It is just to the south and west of Metsiphi.  Here is a view of it from the air (N at the top):


Google marks a church here which it calls Haghios Ioannis (F5698).  The area to the left was probably cultivated in ancient times.  

About Metsiphi Fachard says 
'The most probable hypothesis seems to us to be that of a farm exploiting the little valley of Haghios Ioannis."(5)

Here's my final reconstruction of Reber's photo as taken from Metsiphi itself (foreground):


... with Reber's photo again for comparison:



Metsiphi is C6878 in the Mycenaean Atlas.  Its coordinates are 38.147513 N, 24.278 E

And a final map with everything labelled:






1. Styra
2. Haghios Nikolaos (Acropolis of Styra AND Fortress of Larmena/Armena)
2a. Kiapha Pass (col, Sattel)
3. Koryphi peak (682 m)
4. Metsiphi and Haghios Ioannis



The reproduction of landscape views in Google earth is a good technique that I have used successfully many times in the past and I encourage you who trying to locate sites from photographs to try it.

Glossary of Place Names at Haghios Nikolaos ridge:

I used the following geographic terms in the specific way explained here:

The term 'Haghios Nikolaos' (sometimes 'Diakofti') is reserved in this post for the small plateau at the west end of the Kliosi massif, elev. 648 m ( 38.146118° N,  24.262697° E).  It is right at the ridge-line and overlooks a small pass (called by Fachard [2012] the Kiapha Pass, F5694) just a few meters to the NE.  This plateau takes its name from a nearby chapel cut into the rock just off to the west and named for Haghios Nikolaos.  Do not confuse this chapel with the church dedicated to the Virgin (F5700, another Panaghia?), placed prominently at the center of this plateau.

In this post the name 'Armena' (also 'Larmena' and with numerous alternate names and transliterations; F5654) is reserved for the great 13th century walled stronghold located on Haghios Nikolaos.  This corresponds to Fachard [2012] 229, no. 170, 'Aghios Nikolaos: Château-Fort d'Armena'.

Just to the W of the fortress of Armena, and adjoining it, was located a classical period fortress (in Fachard [2012] 225, no. 169) of which some walls and a famous and often photographed gate are the principal remains.  There is a plan of the remains of this specific fort in Fachard Fig. 190.  Photographs of the gate are in Reber [2002], Taf. 10, nos. 2 and 3.  A very helpful map of both the classical fortress and the Armena fortress is given in Ducrey et al. [2005], 121, fig. 4.  This classical period fortress is often referred to as 'The Acropolis of Styra' (F5701) and I have used that name for convenience but Reber [2002] 44 casts doubt on the idea that it could have had such a purpose given its great distance (~ 2 km.) from that city and therefore this appellation should be used with caution.  Fachard [2012] calls this classical period fortress 'Aghios Nikolaos' (6) but I have reserved that name as the geographic designator of the entire plateau.

The term 'Koryphi' ('Korifi'), alt. 682 m. is reserved for the peak of the Kliosi mountain ridge located about 1700 m to the NW of 'Haghios Nikolaos' at 38.160292° N, 24.279566° E.  Here it is given the feature name  F5699.

The Kliosi range (often referred to as a single mountain) is a long ridge that begins at the north-east of our area and runs to the south-west for about 15 km.  One of its high-points is Koryphi at 682 m asl.  Another is Haghios Nikolaos itself at 648 m asl.

Footnotes

(1) Fachard [2012] 336, no. 171. “Du col de Kiapha, situé à quelque 300 m au nord de la porte du château vénitien de Larmena, on peut suivre un chemin (antique ?) en direction du vallon d’Aghios Ioannis. À environ 1 km à l’est du col, on remarque une construction ancienne et une borne rupestre, toutes deux découvertes par N. K. Moutsopoulos.”

(2) Reber [2002] 45. “Von Styra aus führten in der Antike zwei verschiedene Wege nach Karystos. Der eine entsprach ungefahr dem Verlauf der heutigen Strasse, der andere führte von Styra zuerst nach Osten und folgte danach in leichtem Anstieg dem Nordhang des Kliosi. Uber einen Sattel ostlich der Befestigungsanlage gelangte man zuerst in eine Schlucht und von dort uber einen niedrigen Sattel in das weite Tal von Stoupaioi. Von Stoupaioi führte der Weg durch das Gebirge nach Süden, wo er sich hinter dem Dorf Vatisi mit dem zuerst genannten Weg vereinigte.”


(3) Idem. “Folgt man dem streckenweise mit antiken Stützmauern befestigten Weg nach Stoupaioi, so trifft man unterhalb des Sattels bei der Stelle Metsiphi auf die Ruinen eines antiken Gebaudes, das von N. K. Moutsopoulos freigelegt worden ist.”

(4) In Reber [2002] Plate 11.1

(5) Fachard [2012] 336: "L’hypothèse d’une ferme exploitant le petit vallon d’Aghios Ioannis nous semble la plus vraisemblable." 

(6) Fachard [2012] 169, 'Aghios Nikolaos: Forteresse; 169; ... '.

BIBLIO

Ducrey et al. [2005]:  Ducrey, Pierre and Sylvian Fachard, Thierry Theurillat, 'Les Activités de l'École Suisse d'Archéologie en Grèce 2004',  Antike Kunst (48) 112-123. 2005.   Online here.

Fachard [2012]: Fachard, Sylvian La Défense du Territoire; Étude de la Chôra Érétrienne et de ses Fortifications, École suisse d'archéologie en Grèce, InFolio Editions, CH-Gollion.  2012.  Online here.

Reber [2002]: Reber, Karl 'Die Südgrenze des Territoriums von Eretria (Euböa)' Antike Kunst (45) 40-54. 2002 Online here.



Monday, February 24, 2020

Thoughts about intervisibility, Part 2

In my last post I tried to suggest that intervisibility was a human idea and not one strictly mathematical.  Sure, if the math shows a big obstacle between sites A and B then they are not intervisible.  There are gradations however.  Suppose a town is just barely behind an obstacle (like a ridge).  Mathematically speaking your town and that town are not intervisible.  But you can see the smoke from their fires during the day and a glow in the sky at night.  If, imagining the worst, an enemy destroys that town you will surely see the smoke from the fires and know that something is wrong.

I've tried to make allowances for such situations in the intervisibility software on the Mycenaean Atlas.  Of course I add 1.8 m to the elevation of the source site (site A) in order to mimic the height of an observer.  And now I've also added 3 meters to the elevation of the target site (site B) in order to get rid of some edge cases where site B sits juuuussst below the horizon but really should be counted as intervisible.

The point is that this intervisibility page is a tool for exploring intervisibility.  The mathematics cannot definitively make a decision about a fundamentally human idea.  If you see a result that you don't agree with then you should pursue it further and make up your own mind.

It's easier to do that now because my friend Xavier Fischer, of elevationapi.com, has provided an additional tool.  Now you can generate an intervisibility graph that addresses the sites pairwise.  Here's an example:

This shows the intervisibility sightline from, on the left, Kastro (C714) in the neighborhood of Gla to Magoula   Kavkala (C984) about 2.25 km. distant.  Because no obstacles intrude on the red line then the sites are intervisible.  The bottom scale is distance in km.  The left side scale is elevation in meters.  Notice that I add 1.8 m. to the starting elevation (on the left) and a few meters to the right.  That helps to tip the two sites into intervisibility.

So how do you exercise this fine new tool?




On the new intervisibility page you simply click on the 'true' or 'false' values in column 3 of the intervisibility list.  When you do that the graph will display. 

Here is an example of the I. graph between Kastro (C714) and one of the cemeteries at Hagia Marina (C728) directly to its east.  These two sites are intervisible; the resulting graph is:



You should keep in mind that this graph's x-axis (distance) is compressed in comparison to the y-axis (elevation).  In this particular graph one major division in the vertical (5 m) has the same size as 250 m. in the horizontal - a ratio of 1:50.  So all these graphs are what statisticians call 'Oh boy!' graphs.  Always be sure that you understand the relative scales on these graphs before trying to interpret them.

News of the Mycenaean Atlas Project

On February 12 I delivered version 131a of the database.  It contains many additions and minor changes.  At that time a new version of the software was delivered in order to support intervisibility.

...

And, by the way, friends don't let friends use Facebook.



Saturday, February 8, 2020

Thoughts about Intervisibility




‘ … and now I watch for the light, the signal-fire
breaking out of Troy, … [1]



Before the systematization of linear perspective in the 1400’s painters still needed a way to show that certain things in their paintings were further away. How did they do this?

They used a set of techniques that are collectively known as ‘aerial (or atmospheric) perspective’. These techniques consist of using certain observations about distance with which we are all familiar but which we rarely consider. Its principles are:

a. Things further away are smaller than the same things up close
b. Things further away are bluer than the same things up close.
c. Things further away are of lower contrast (grayer) than the same things up close.

There’s a nice example of this in a painting from 1520 by Patinir:




J. Patinir, Landscape with the Flight into Egypt, ca. 1516.



Here we can clearly see aerial perspective at several removes. There is a slight graying of the fields in the center. This fades into the grayer and bluer mountains at the upper right. 
These in turn transition to the entirely gray and nearly detail-free mountains on the horizon.

Time of day might be a factor in intervisibility. A town to the west that’s visible in the morning might be lost in the sun’s glare in late afternoon and evening. The reverse for towns to your east.

There’s also the curvature of the earth to consider. Consider that towns A and B are sitting on a perfectly smooth earth. At some distance town B will be below the horizon relative to an observer at A. What distance? Well, an object 10 m. in height (32.81 ft.) will be below the horizon at about 16 km (9.9 mi.). [2] This might be a factor in coastal town intervisibility. Otherwise the main factor in intervisibility is height above the horizon of the object to be observed. That’s why signal fires are placed on towers or heights.[3]

Sometimes intervisibility is achieved by indirect means. Crowe details how Polynesian navigators relied on the color of the underside of clouds to pinpoint islands still well beyond the horizon[4]

Kure Atoll, Northwestern Hawaiian Islands.
Image courtesy of NOAA/LT Elizabeth Crapo





These are just some of the circumstances that might prevail such that lines of sight between A and B may be entirely unobstructed and yet B not really visible from A (or vice-versa).


I go into all this in order to make plain that intervisibility consists of more than just unobstructed lines of sight.  

But the Mycenaean Atlas cannot take any of these factors into account. Here the analysis is strictly mathematical – it seeks only to determine whether there is an unobstructed sight-line between location A and location B. This is achieved in the following way.

1. construct a linear function (y = f(x) = Ax + B) that joins the two sites. Here the coefficient A is the tangent line that connects the two sites (Δ elevation (A,B) / Δ distance (A,B)). The coefficient B is merely the elevation of site A.

2. Now the function can be evaluated for any position on a line between A and B.  This is to determine whether any features between sites A and B are higher than the function value at that point.

If no elevations between the sites have an elevation greater than the function evaluation at that point then the two sites are intervisible. If there is some real elevation higher than the function would predict then the two sites are not intervisible. This algorithm is a modification of an intervisibility algorithm described by Blelloch[5]. 





I have had the great good fortune to work with Xavier Fischer of elevationapi.com who, at my request, created a single call that returns the intervisibility status for any two lat/lon pairs. In my original design I needed an internet call for each point evaluated between A and B (at least 16). Such an algorithm runs on Oinp (order of time of average internet fetch * the number of pairs(A’,B’) * the number of partitions between A and B). With the new internet call of Mr. Fischer’s the new algorithm runs on Oip (order of average internet time * number of pairs(A’,B’).

When using this new algorithm I add 1.8 m to the start point to mimic an average observer’s height. This helps, I think, to make some sights intervisible which would not be so if the elevation of the observer was taken as ground level.  This would not be very realistic.

In the Mycenaean Atlas I have created an intervisibility page. It is reached from the Place Key Report by clicking on the new ‘Intervis’ button.





Clicking on that button brings you to this new  page.



The main feature on this page is a map which shows the starting point (A) in blue.  Sites that are intervisible with A are shown with green push-pins.  Sites that are NOT intervisible with A are shown with red push-pins.  Each of the pins on the map has tool-tips which provide the name and place key of the sight.  If you click on a pushpin you will get an info box that contains more information along with a link.  Clicking on the link takes you to the Place Key Report page for that specific site.

The other main feature on this new page is the intervisibility list on the left.  This list shows all the sites that are within 6.5 m. from the center site (A).  Each line has a link.  If you click on that link you will be taken to the intervisibility page with your clicked-on site as the new center (A) site.  That way you can remain in the intervisibility domain while you check sight lines from various origins.  The list's intervisibility column simply gives the values 'true' or 'false' for each of the set of sites.  Each column in this list is sortable.

Here's one more view of our new page.  It shows the intervisibility from a  peak sanctuary C6228,  Petsofas Peak Sanctuary in Siteia.   Its elevation is 251 m.




We can check the accuracy of this very easily in Google Earth.  I drew a straight line from the peak sanctuary at C6228 to C5107 which is one of the sites that is supposed to be intervisible with C6228.  I then did a 'Show Elevation Profile' on that straight line and this is the result:



You can clearly see from the Elevation  Profile that there are no obstacles intervening between the two sites.

I hope that you will enjoy using this new tool and that you'll find it useful.


Some Bibliographical Remarks

A general survey of the history of intervisibility in archaeological practice may, perhaps, be had here:

Wheatley, David   'Making Space for an archaeology of place' (especially part 4. Visibility Studies), [2004]  Internet Archaeology, (15) Online here.

Two  nice case studies of the use of intervisibility as part of landscape analysis are:

1. Sylviane Déderix, 'Patterns of Visibility, Intervisibility and Invisibility at Bronze Age Apesokari (Crete)' Open Archaeology (5), 187-203.  Online here.

I particularly recommend this article.  She proposes a number of hypotheses about the position of this tholos and supports or refutes them using intervisibility and viewshed ideas.  This is a good example of how it should be done.

2. Criado Boado, Felipe, and Victoria Villoch Vázquez. 'Monumentalizing Landscape: From Present Perception to Past Meaning of Galician Megalithism (Northwest Iberian Peninsula).' European Journal of Archaeology (3:2) (2000): 188–216.  Online here.



Footnotes

[1] Aeschylus. Agamemnon, ll. 4-11.

[2] For a calculator see this.  

[3] For an amusing discussion of signal fire parameters in The Lords of the Rings see this.

[4] Often attested. Crowe [2018] 91. Worth quoting in full:

In the case of a particularly shallow lagoon, the navigator even may be guided to it by the turquoise tint of the water reflected up onto the underside of a cloud. Striking examples of this include the unusually shallow lagoons of Aitutake (S. Cook Is) and ‘Ana ‘a (Tuamotus), where the presence of these low-lying atolls can be discerned in fine weather from up to 70 km away. This kind of phenomenon can show up in other cases, too, where the destination island can even be distinguished by the colour of the cloud hanging over it – a green tinge in the case (of) a forested island; an unusually bright cloud over white sand or surf, or a pink tinge warning of a reef.” And see notes 37-43 for this chapter.

At 70 km from the observer the curvature of the earth will completely occlude an object up to 334 m (1095.8 feet) in height.

[5] See De Floriani and Magillo [1999] 549. Also Blelloch [1990] 40.

Bibliography

Aeschylus: The Oresteia, Translated by Robert Fagles. Penguin, 1975

Blelloch [1990]: Blelloch, Guy E. Vector Models for Data-Parallel Computing. MIT Press, Cambridge, Massachusetts. 1990.

Crowe [2018]: Crowe, Andrew. Pathway of the Birds; The voyaging achievements of Maori and their Polynesian ancestors. University of Hawaii Press, Honolulu, Hawaii. 2018. ISBN: 978-0824878658

De Floriani and Magillo [1999]: De Floriani, Leila and Paola Magillo, ‘Intervisibility on Terrains’, 543-556. 1999. It is online here.