The Bronze Age Eruption of Santorini and Late Minoan IB Destruction Event

The Bronze Age Eruption of Santorini and
Late Minoan IB Destruction Event

The Late Minoan I (LM I) period as a whole represents the zenith of Minoan civilization. Their cultural and maritime economic influence throughout the Mediterranean and Black Sea would never be exceeded. This was a time of great social and political cohesion and commercial and industrial prosperity. Their only economic rival in the Mediterranean was the Egyptians. The Minoans at this time ruled the seas with the largest navy and commercial fleet ever seen in the Mediterranean. Then it all came crashing down with the incredible eruption of the Theran marine (sea-level) volcano at present day Santorini, Greece in about 1628 B.C.

Mount Rinjani Eruption
Lombok, Indonesia
1994

The palaces and cities situated on the low-lying coastal plains along the northern and eastern coasts of Crete like Malia, and Palaikastro were terribly damaged by tsunamis generated by the eruption. Malia was nearly scrapped to its foundations by the tremendous force of the water. But, all of the southern and inland urban areas at higher elevations like Knossos, Phaistos, Archanes, Galatas, Kommos, and Vassiliki were utterly unaffected by the waves. While the tsunami destruction would have been a terrible tragedy with many thousands of deaths the much greater mass of the Minoan population would have survived completely untouched. This is conclusively demonstrated by the GIS publication:

"The Extent of the Santorini Eruption's Tsunami Inundation of Minoan Crete"

Relatively little ash from the volcano fell on Crete and the Minoans had vigorously recovered from several large earthquake events in the past. The Mycenaeans were far too weak and totally incapable of mounting a naval invasion of Crete to have caused any human-based destruction at this time and there are no archaeological signs of internal strife or civil war on the island.

The Late Minoan IB Destruction Event

The event that really brought the entire Minoan civilization to its knees was a massive fire destruction of central and eastern Crete that occurred at about the same time as the eruption. It was so overwhelmingly catastrophic that apparently most, or all, of the remaining palaces, towns, and villas in central and eastern Crete that survived the tsunamis were decimated by fire. The archaeology is resoundingly clear in that it did happen. There is significant evidence of an intense spectacular fire destruction at several sites - Ayia Triada, Gournia, Malia, Palaikastro, Petras, Phaistos, Sklavokambos, Zakros, etc. It seems the conflagration came upon them without warning by some unknown cause.

This fiery cataclysm is called the Late Minoan IB (LM IB) destruction event. It was so wide spread that many scholars describe it as a destruction horizon. Science has never been able to definitively explain its cause. Though damaged Knossos was repaired to a degree and continued to carry on in some reduced fashion in the following periods. All of the other palaces were fiercely burned and abandoned forever! The LM IB destruction event marks the abrupt end of the Late Minoan I period. What could possibly have caused this disaster?

Pottery as a Marker of Relative Chronology

Before the advent of radiocarbon techniques in the 1950’s the conventional Minoan dating systems were entirely based on the relative chronology of pottery styles associated with excavated archaeological strata. While pottery styles provide a useful low resolution view of the chronology of prehistory they cannot be used to accurately fix calendar dates to Bronze Age events. For instance, there is no clear transition boundary for the beginning of one style and the end of another. There is always an overlapping period of unknown duration during the transition. Moreover there is no definitive way of accurately determining the length of time encapsulated by a particular style. It is possible that a time period based on a style of pottery that is assumed to be 50 years is actually only a few years in length or even possibly more than a hundred years.

When a shard of pottery is securely excavated from a particular archaeological context it gives us a relative indication of when the piece was deposited only. It tells us nothing about the history of the artifact or when it was manufactured except that it was made some unknown time before its deposition. An example of this could be the very finely made “Marine Style” pottery of the LM I period. They were probably considered beautiful works of art and would have been very prized by their owners. An artistic piece of this quality could have been handed down through the generations as a family heirloom and made many decades before it finally crashed to the floor in some earthquake or war.

Late Minoan I Pottery

The ceramic transition into the LM I period is identified by a shift from light-on-dark to dark-on-light treatments on painted pottery. The LM I period is subdivided into the LM IA and LM IB periods. The great majority of LM I pottery is remarkably consistent and any differences in style are difficult to determine but at some time during this period examples of very distinctive, finely made ceramic art began to appear. This distinguishes the LM IB period from that of the LM IA in the archaeology. Two of the styles associated with LM IB pottery are the Marine and Alternating styles. The Marine Style is decorated with dense beautifully done marine motifs. Their remains are found in LM IB archaeological strata throughout the southern Aegean. Many experts believe these extremely fine vases represent the highest technical and artistic achievement ever made by the Minoans in ceramic art (Rutter, 2000).

The majority of pottery so far excavated from Akrotiri is clearly Cycladic and not Minoan. This majority is comprised of local and imported Middle (MC) and Late Cycladic I (LC I) wares. While Minoan pottery was clearly influential their importation from Crete or elsewhere never surpassed local production. Minoan pottery at Akrotiri is primarily represented in the form of stirrup jars which were used in the maritime commercial trade of liquid commodities like wine and olive oil. Therefore the assumption that Akrotiri is a definitive indicator of Minoan material culture as expressed in the pottery is weak at best.

Akrotiri is a very unique Minoan archaeological site. It is the only one known to me that doubtlessly underwent a highly organized mass evacuation. Apparently all of the people and their valuables were transported elsewhere before the main eruption. No human remains and almost no valuables, jewelry, or seal stones have so far been found. Only one small golden artifact has been discovered on the site – the Golden Ibex (Goat). Akrotiri is archaeologically dated to the earlier LM IA period for the sole reason that no finds of LM IB Marine Style, etc. pottery have so far been found in its volcanic destruction layer.

But, wouldn’t they have taken their finest, most expensive vases and other ceramic art with them while leaving behind their more mundane, utilitarian, and inexpensive pottery? Why fill up the precious space on their evacuation ships with cheap or heavy storage pottery? The assumption by some that no Marine Style pottery ever existed on Akrotiri because none has so far been found there is equivalent to saying that the Therans possessed little or no jewelry or gold for the same reason. Both of these assumptions are far too weak to be considered reliable indicators of the evacuated site’s true character or chronology.

Pottery Excavated from Akrotiri
Akrotiri, Santorini, Greece

By scrutinizing the entire collection of pottery excavated at Akrotiri it is apparent that very high quality fine vases and examples of exquisitely done ceramic art of any kind are conspicuously missing. I do not equate Vapheio cups, Keftiu cups, or other well done but not top quality pieces with the truly fine vase art that is not represented in the assemblage. It defies logic to assume they wouldn’t have possessed exceptional examples of ceramic art that reflected the sublime aesthetic sense so richly displayed in their wall frescoes.

Marine Style Minoan Vase
Archaeological Museum of Herakleion Crete
Photo: Agon S. Buchholz

They couldn’t take their superlative yet immovable wall art, but they could take their superb yet portable vase art onto the evacuation ships with them. Apparently their most expensive and prized ceramic objects along with their jewelry and other valuables were removed in the face of the looming cataclysm. If any Marine Style, etc. vases were present in Akrotiri before the eruption they almost certainly would have accompanied their owners in their flight. Therefore, on closer examination, Akrotiri’s volcanic destruction layer cannot be definitively excluded from a Late Minoan IB context.

Radiocarbon Dating

In order for any relative chronology based on pottery to be defined in absolute terms there must be attempts to accurately fix the artifacts in time by some other direct scientific means. The primary method used to date organic material found in archaeological strata is radiocarbon dating. The unstable radioisotope carbon-14 is continually created in the upper atmosphere by cosmic rays. As plants take up carbon dioxide from the atmosphere through photosynthesis they absorb carbon-14 and other organisms ingest it when they consume the plants. All living things continually process carbon-14 from their environment throughout their lifetime. Death stops the intake of the isotope and the amount of carbon-14 begins to gradually decrease through radioactive decay.

By measuring the amount of carbon-14 remaining in an organic sample it provides an indication of its age. The isotope has a half-life of about 5,730 years and can be used to measure the age of organic materials up to about 45,000 years. There are many variables that affect the accuracy of radiocarbon dating. The concentration of carbon-14 in the atmosphere varies with time and geography. The intensity of cosmic rays entering the atmosphere changes with variations in the sun’s activity and the earth’s magnetosphere. The concentration can also be affected by the vast amounts of carbon contained in the oceans, sedimentary rocks, and organic matter which can be exchanged through erosion, climate change, human activity, etc. Volcanic eruptions can pump great amounts of carbon into the atmosphere and affect the carbon-14 concentration.

All of this variation over time needs to be compensated for by means of a calibration curve if any reasonable accuracy is to be achieved. Calibration curves are developed through the study of tree growth rings, deep ocean and lake sediment cores, etc. As one can imagine, this requires a great deal of effort and has been ongoing for decades. In 2004 a new calibration curve (IntCal04) was internationally ratified for calibrated dates back to 26,000 years Before Present (BP).

Tree-Ring Dating – Dendrochronology

Dendrochronology is a method of scientific dating based on the analysis of tree ring growth patterns. This technique can date the tree rings in many types of wood to the exact calendar year each ring was formed. For the entire period of a tree's life, a year-by-year record or ring pattern is formed that reflects the climatic conditions in which the tree grew. Adequate moisture and a long growing season result in a wider ring. A drought year may result in a very narrow one. Strongly varying poor and favorable conditions can result in several rings forming in a given year. While archaeologists can use this technique to date the year a piece of wood died, it has its limitations. The age of a structure in which the wood was contained cannot be definitively determined. It may have been reused from an earlier application, or the felled tree may have been left in a lumber yard for a long period before it was used.

So far the most precise carbon-14 calibrated date distribution determined by direct scientific means for the Minoan eruption of Santorini is 1627 to 1600 BC with a 95.4% (2ó) probability or 1621 to 1605 BC with a 68.3% (1ó) probability. This is based on the radiocarbon analysis of samples taken from the outermost growth ring of an olive tree found smothered to death in its life position by volcanic ash. The tephra protected the tree from the heat of the eruption and preserved it for future analysis. X-ray tomography was used to accurately identify the tree's growth rings and the samples were “wiggle-matched” to the latest radiocarbon calibration curve IntCal04 using the University of Oxford's Bayesian statistical modeling calibration program OxCal.

"Santorini Eruption Radiocarbon Dated to 1627-1600 B.C."
Walter L. Friedrich, Bernd Kromer, Michael Friedrich, Jan Heinemeier, Tom Pfeiffer, Sahra Talamo. 2006.

The End of Minoan Hieroglyphic and Linear A Writing

There came a time when I decided to build a Google Earth GIS (Geographical Information System) dataset for the public based on the archaeological sites listed in John G. Younger’s excellent publications:

"The Cretan Hieroglyphic Texts"

"Linear A Texts in phonetic transcription"

Linear A Tablets
Akrotiri, Santorini, Greece

My original intention was to provide a sound educational GIS document for those interested in the temporal geographical distribution of the archaeological sites associated with the excavated finds of Minoan Hieroglyphics, Linear A, Trojan Script, and Mycenaean Linear B writing from the Bronze Age Aegean. I found the result of this project quite extraordinary! With very few possible exceptions, all of the archaeological finds of Minoan Hieroglyphic and Linear A writing date from about 2200 BC up to the time of the Late Minoan IB destruction event. Only a handful of Linear A finds show up in the period that followed. In the words of John G. Younger, “It is therefore possible that Linear A survived the LM IB destructions, though barely”. This phenomenon can be clearly seen in my GIS publication:

"The End of Minoan Linear A Writing and the LM IB Fire Destruction of Crete"

The Phaistos Disk
Phaistos, Crete, Greece

The practice of writing was widely distributed throughout central and eastern Minoan Crete. Writing had been well established among the Minoans for hundreds of years leading up to the destruction. The sharp contrast between the many Linear A archaeological sites on Crete before the destruction and the mere two Linear B sites in the Mycenaean period that followed is incredible. This seems to imply a mass decimation of the Minoan population on Crete. What could possibly have caused the end of writing of an entire people on Minoan Crete?

The Theran Pyroclastic Surge Theory

In 2007 I wrote a paper for the Thera Foundation that theorized a high-speed long-runout pyroclastic surge(s) (gas bloom of mainly superheated dry steam) generated by the eruption of the Theran marine (sea-level) volcano had struck large areas of central and eastern Crete and set them ablaze.

"The Minoan Catastrophe: The Theran Pyroclastic Surge Theory"

The Late Minoan IB destruction event is a perfect fit for the effects of this hypothesis. The theory provides an entirely scientifically valid causal mechanism for a fire destruction of Crete – massive pyroclastic superheated steam surge activity from the Minoan eruption of Santorini. It is undeniable that if Thera’s rising magma mixed with the Aegean Sea there would have been phenomenal explosions of superheated steam and significant gas surge activity in the surrounding area. Whether they reached Crete or not remains to be determined by the evidence.

Pyroclastic Surge over Water
Montserat, Caribbean
1996

It is clear from the sedimentary evidence left by the eruption on Santorini that it produced many pyroclastic surges and the volcano's vent generally ejected more material to the southeast. During the upper part of the eruption's second major phase (Minoan B or Bo2) something extraordinary occurred. A tremendously powerful superheated steam surge(s) exploded from the vent and was funneled by the high walls of the Gavrillos Ridge to the east and the Akrotiri hills in the west on a southern course aimed directly at the northern coast of Crete. It was so massively violent that it utterly obliterated the structures in Akrotiri that remained uncovered by tephra from the eruption's previous activity (McCoy, Heiken, 2000).

The chronological association between the Minoan eruption and the LM IB destruction has been debated for decades and remains unresolved. But, I believe there is compelling evidence that the incredible eruption of the Theran marine volcano and the Late Minoan IB destruction event actually describe the cause and one of the effects of the same event. The phenomenon of the pyroclastic steam surge is well documented in modern times (Krakatau, Mt. Pelee, etc.) and should no longer be left unconsidered as a possible cause of the LM IB destruction horizon.

Lifting the Fog in the Evidence

Besides the considerable evidence of fire destruction at many archaeological sites on Crete, the theory calls for literally everything combustible being fiercely set ablaze almost simultaneously within the areas touched by the superheated gas blooms. If this is true, the blanket of fire should have produced an immense amount of soot, charcoal, and other organic or chemical evidence in the LM IB stratigraphy that closely dates to the Minoan eruption. There has been relatively little effort expended on radiocarbon dating the LM IB destruction horizon and only one known to me that incorporates the new IntCal04 calibration curve.

Radiocarbon multi-modal calibrated age distributions that can span 100 years or more are simply not accurate enough to be of any use in this matter. Only the most advanced techniques in radiocarbon dating and dendrochronology like those used by Friedrich et al. in 2006 to date the Santorini eruption can possibly hope to render the greater resolution required to more definitively assemble the true chronological relationships of the events of the LM I period.

Also, there should be wide-spread sedimentary evidence from the pyroclastic surges generated by the Minoan eruption. These highly energetic gas blooms are low-density mixtures of primarily superheated dry steam that contain ash and rock debris held in turbulent suspension. As the bloom jets away from its blast vent it leaves a record of its trajectory and coverage by continually raining ash and rock into the water and onto the land it touches due to the pull of gravity. As the bloom travels farther away from the volcano the thickness of its sediments decrease as more and more ash and debris falls out of its turbulent suspension. The eruption of the marine volcano Krakatau in 1883 left steam surge deposits composed of poorly sorted mixtures of ash and pumice on islands from 20 to 40 kilometers away that were tens of centimeters thick. Krakatau's pyroclastic gas blooms were able to reach out to a distance of about 80 kilometers before finally dissipating.

Using the Krakatau sediments as a reference the magnitude of the surge deposits left by the Minoan eruption need to scaled up considerably. The Bronze Age eruption was about nine or ten times bigger than Krakatau. Its surge deposits should be significantly thicker and have a much greater reach. The sediments on the islets and islands surrounding Santorini that were struck by its gas surges, as some of them must have been, should consist of a thin layer of perhaps fifty to less than ten centimeters depending on the distance from the volcano and be composed of fine-grained, glassy ash that can be found in places resistant to erosion like lakes, depressions, or where the strata has been covered over by fallen structures, landslides, etc.

These deposits will be difficult to identify because they will most likely coexist with the eruption's ash fall and its reworked components laid down in the midst of significant seismic activity. But it is possible that surge-based ash deposits can be found relatively isolated from the ash fall. The deposition of ash fall is quite dependent on the prevailing winds while the course of a high-speed pyroclastic gas bloom would, at least initially, be determined solely by the orientation and configuration of the explosive opening of its blast vent(s).

In the decades following the eruption these deposits may have been disturbed by human activity or destructions during the LM II or Mycenaean period and over the millennia they would have been shaken many times by the perennial scourge of the Aegean - large seismic events. But when provided with good diagnostic samples their definitive detection should not escape the expertise of a qualified volcanic geologist. To the best of my knowledge no published scientific effort has ever been undertaken to look for these deposits in the Aegean.

After the wonderful effort that scholars devoted to more accurately dating the Theran eruption by direct means, I believe a fruitful path for future research would be to apply the most advanced techniques in radiocarbon and sedimentary analysis to the stratigraphy associated with the LM IB destruction on the many islets and islands in the vicinity of Santorini. As the geographical center of mass for the Minoan population, central and eastern Crete should be given special consideration (Baird, 2008). This would surely bring us closer to finally lifting the fog in the evidence so the truth behind the great mystery of the Late Minoan I era can be more clearly revealed.

W. Sheppard Baird
April 30, 2009

Bibliography:

Walter L. Friedrich, Bernd Kromer, Michael Friedrich, Jan Heinemeier, Tom Pfeiffer, Sahra Talamo. “Santorini Eruption Radiocarbon Dated to 1627-1600 B.C.”. 2006.

The Thera Foundation

J. V. Luce, C. Doumas. "The Chronology of the LM I Destruction Horizons in Thera and Crete ". "Thera and the Aegean World I". Second International Scientific Congress. Santorini, Greece, pp. 785-789, 1978.

W. S. Downey, D. H. Tarling. "Archaeomagnetic Results from Late Minoan Destruction Levels on Crete and the 'Minoan' Tephra on Thera ". "Thera and the Aegean World III". Volume Three: "Chronology", Proceedings of the Third International Congress, Santorini, Greece, pp. 146 - 159, 3-9 September 1989.

Rutter, Jeremy B. "Lesson 14: Late Minoan Painting and Other Representational Art: Pottery, Frescoes, Steatite Vases, Ivories, and Bronzes". "The Prehistoric Archaeology of the Aegean". Dartmouth College. March 18, 2000.

C. Doumas, A. Papagiannopoulou. "A Study of Middle and Late Cycladic Pottery from Akrotiri". Thera and the Aegean World III. Volume One: "Archaeology". Proceedings of the Third International Congress, Santorini, Greece, pp. 441-448, 1989.

M. Marthari. "Investigation of the Technology of Manufacture of the Local LBA Theran Pottery: Archaeological Consideration". Thera and the Aegean World III. Volume One: "Archaeology". Proceedings of the Third International Congress, Santorini, Greece, pp. 449-458, 1989.

Joseph W. Shaw, Aleydis Van de Moortel, Peter M. Day, Vassilis Kilikoglou. "A LM IA Ceramic Kiln in South- Central Crete: Function and Pottery Production". American School of Classical Studies, Hesperia, Supplement 30, 2001.

Rutter, Jeremy B. "Lesson 17: Akrotiri on Thera, the Santorini Volcano and the Middle and Late Cycladic Periods in the Central Aegean Islands". "The Prehistoric Archaeology of the Aegean". Dartmouth College. March 18, 2000.

F. W. McCoy, G. Heiken. "The Late-Bronze Age explosive eruption of Thera (Santorini), Greece: Regional and local effects“. Geological Society of America. 2000.

S. Carey, S. Sigurdsson, C. Mandeville, S. Bronto. “Pyroclastic Flows and Surges over Water: an Example from the 1883 Krakatau Eruption”. Bulletin of Volcanology. 1995.

T. H. Druitt, L. Edwards, R. M. Mellors, D. M. Pyle, R. S. J. Sparks, M. Lanphere, M. Davies, B. Barriero. "Santorini Volcano”. 1999.

Jennifer Susan Gilbert, Robert Stephen John Sparks. “The Physics of Explosive Volcanic Eruptions”. T. H. Druitt. “Pyroclastic Density Currents”. p. 145. Geological Society 1998.

John G. Younger. "Linear A Texts in phonetic transcription“. 2009.

John G. Younger. "The Cretan Hieroglyphic Texts“. 2008.

W. Sheppard Baird. "The End of Minoan Linear A Writing and the LM IB Fire Destruction of Crete“. 2009.

W. Sheppard Baird. "The Extent of the Santorini Eruption's Tsunami Inundation of Minoan Crete“. 2008.

W. Sheppard Baird. "The Archaeological Sites of the Aegean Minoans“. 2008.

W. Sheppard Baird. "The Minoan Catastrophe: The Theran Pyroclastic Surge Theory“. "The Thera Foundation“. 2007.

Sturt W. Manning, Christopher Bronk Ramsey, Walter Kutschera, Thomas Higham, Bernd Kromer, Peter Steier, Eva M. Wild. "Chronology for the Aegean Late Bronze Age 1700–1400 B.C.”. 2006.

Rupert A. Housley, Sturt W. Manning, Gerald Cadogan, Richard E. Jones and Robert E. M. Hedges. "Radiocarbon, Calibration, and the Chronology of the Late Minoan IB Phase”. 1999.

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Radiocarbon WEB-info. Tom Higham, Radiocarbon Laboratory, University of Waikato, New Zealand.