Excavations at Pseira: The Evidence for The Theran Eruption

More than twenty pieces of waterworn pumice have been recovered from the new excavations. The earliest context is from LM IA, and analysed samples match the products of the Theran LM IA eruption. Windblown ash from the Theran eruption has been noted from a secure LM IA context, as well as from an agricultural terrace near the settlement. One artefact made from pumice was recovered from a Late Minoan IB level. The conclusion is that the LM IA eruption of Thera preceded the LM IB destruction of Pseira.

INTRODUCTION

Pseira is a small island off the shore of north-east Crete. It was first inhabited in the Final Neolithic / Early Minoan I period, and the settlement expanded in the Middle Bronze Age and again in the Late Bronze Age, reaching its greatest size in Late Minoan I. After a destruction in LM IB, the town seems to have been abandoned for a short time. A reoccupation in LM III was followed by another abandonment, and the island may have had only intermittent visitors until the 6th century AD.

The Minoan settlement and its nearby cemetery were excavated in 1906 and 1907 by Richard Seager (Seager 1910). The excavations uncovered much of the LM IB town, consisting of more than sixty buildings. Houses were situated on both sides of a small harbour that faced south-east, towards Crete. They were built mostly of stone, with more than one storey of construction being common. Among the finds were painted plaster reliefs depicting women in elaborate costumes, many stone vases, and fine examples of LM IB pottery including several vases imported from Knossos. The LM IB pottery is so canonical for the period it has often been used to help define the ceramic phase (Betancourt 1985, 133-148).

The modern excavations at Pseira began in 1985 under the joint direction of Philip Betancourt and Costis Davaras (for preliminary reports see Betancourt and Davaras 1986; 1988a; 1988b). In addition to the archaeological excavation, the project includes surface survey (supervised by Richard Hope Simpson), architectural study of the buildings excavated by Seager (supervised by John McEnroe), and a broad programme of study and analysis (co-ordinated by Philip Betancourt). This paper presents some of the new evidence for the relation between the occupation of Pseira and the eruption of the volcano of Thera.

WATERWORN PUMICE

More than fifty pieces of waterworn pumice have been recovered from the new excavations. All the pieces are similar in appearance. They are small (under 10 cm), with worn, rounded surfaces. Although the earliest pieces come from LM IA, they have been found as late as the Byzantine levels at the site. The most securely datable group from LM IA was found in Building AC.

Building AC (the Shrine) is on the eastern side of Ridge Road, a lane that runs along the top of the peninsula where most of the houses are located (for discussion of the building see Betancourt and Davaras 1988a, 215-218). Pumice was found in two rooms, AC 1 and AC 10. The piece in Room AC 10 was in the building's LM IB destruction level, but the three pieces in Room AC 1 were found in a trench excavated into an LM IA level beneath the LM IB floor (Fig. 1).

Room AC 1, the largest room in the building, used bedrock at the north of the room and a rubble packing at the south to create a level floor. LM IA sherds were found in the rubble beneath the floor in AC 1 and also in a contemporary packing outside the building's doorway (associated with the deposit in AC 1 by sherds that physically joined), fixing the LM IA date of the structure's final remodelling. A selection of the sherds from this stratum, being studied in detail by Eleni Banou, is illustrated in Fig. 2. Stratigraphically, there is no doubt the pumice was buried beneath the floor of the building's final phase.

The pumice was examined by Charles Vitaliano at the Department of Geology, Indiana University. Its index of refraction (1.509 ± 0.002) matches that of the pumice from the LM IA eruption of Thera (Ninkovich and Heezen 1965), and the mineralogy of the sample also matches that of the Theran eruption. The samples contained orthopyroxene, apatite, albite, and clinopyroxene, minerals which are the hallmarks of the Theran eruption products from the eruption of the Minoan period.

WINDBLOWN TEPHRA: THE SETTLEMENT

Earth samples were examined from several buildings in order to see if traces of windblown volcanic ash were present at the site. A series of four samples from the Shrine came from the following contexts (for the locations see Fig. I): 1) AC 9-2 (MM ?); 2) AC 14-2 (MM ?); 3) AC 1-4 (LM IA); 4) AC 10-2 (LM IB).

The earth samples came from three successiye levels: a Middle Minoan (?) terrace beneath the level of the LM I strata (contexts AC 9-2 and AC 14-2); the LM IA rubble beneath the floor in Room AC 1 (context AC 1-4); and the LM IB destruction that marked the end of the building's use (context AC 10-2). None of the contexts had been disturbed by Seager's excavations.

The samples were examined at the Geology Laboratory, Indiana University, by Charles Vitaliano. A number of constituents were noted; they are listed in Fig. 3. Although volcanic ash particles from other eruptions were noted in three samples, particles whose index of refraction matched that of ash from the LM I eruption of Thera were found in only one sample, the LM IA sample from the lower level of the same stratum that yielded the pieces of waterworn pumice (for the location of the trench into the LM IA level in Room AC 1 see Fig. 1). The date is well documented both stratigraphically and by the presence of LM IA sherds (Fig. 2).

WINDBLOWN TEPHRA: AGRICULTURAL TERRACE G2

The archaeological survey of Pseira Island is studying many aspects of the use of the island, including its exploitation for agricultural purposes. As a part of the study of the Minoan terraces, selected examples are excavated to document the stratigraphy and the nature of the soils retained behind the walls. A section of terrace G 2 is shown in Fig. 4. The Minoan date of the terrace is proved by the inclusion of Minoan sherds within its soil as well as by the presence of such sherds on the surface. Two chronological horizons were noted, a lower one with Middle Minoan sherds and a higher one with LM I sherds. It is possible that the sherds arrived at the terrace along with refuse used as fertilizer.

Earth samples from the superimposed stratigraphic levels in terrace G 2 were collected as consolidated blocks of earth. They were examined as micromorphology samples by Paul Goldberg at the Institute of Archaeology, Hebrew University of Jerusalem. For micromorphological investigation, the samples are impregnated with polyester resin, sawed, and prepared as thin sections. They are viewed under the polarizing microscope using conventional petrographic procedures and techniques. A wide range of microscopic observations are available with the technique.

A substantial number of windblown volcanic ash particles were detected in the upper 20 cm of the earth from terrace G 2. No ash was noted from the lower levels of the terrace fill. The stratum with the ash (the upper part of stratum B in Fig. 4) dates to LM I. The sherds are not diagnostic enough to distinguish between LM IA and LM IB.

THE ARTIFACT OF PUMICE

The Plateia House, a large building at the north of the town square in the Pseira settlement, was destroyed in LM IB. A shaped and drilled piece of pumice, perhaps a float for fishing, was found in the LM IB level of the building. The artefact is illustrated in Fig. 5. Although it has not been analysed for its index of refraction, the artefact is visually identical to the other pieces of pumice from Pseira.

DISCUSSION

The finds of pumice and ash from Pseira are of interest as a means of fixing the chronological relationship between the eruption of Thera and the coastal towns of eastern Crete. As both the windblown tephra and the pieces of waterworn pumice indicate, the eruption must be equated with LM IA at Pseira, not with LM IB. The presence of both classes of volcanic material below a floor in a building that was used in LM IB prove definitely that the eruption cannot have been responsible for the final destruction of the town. The artefact of pumice, which is most likely from the same eruption, provides additional evidence for the lapse of some time between the eruption and the destruction of the settlement.

The tephra from the agricultural field is the first such find in Crete. More samples are needed for a final evaluation of this evidence, but one possibility is certainly that the ash was deposited over Pseira during the eruption, and that root action and/or cultivation practices mixed it to a depth of c. 20 cm within the upper part of the soil.

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(For figures and tables please refer to book)

Source: "Thera and the Aegean World III, Vol.3" (pp. 96 - 99)

Authors: P.P. Betancourt (,Department of Art History, Temple University, Tyler School of Art, Philadelphia, USA), P. Goldberg (Institute of Archaeology, Hebrew University of Jerusalem, Israel) , R. Hope Simpson (Department of Classics, Queen's University, Kingston, Canada), and C.J. Vitiliano (Department of Geology, Indiana University, Bloomington, Indiana, USA)