• Jerash Hippodrome in Google Earth
  Jerash Hippodrome
  
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• General Plan of Jerash
  Plan of Jerash. North is to the right.
  
  Holger Behr - Wikipedia - Public Domain
  from Wikipedia
• Fig. 22 - Plan of hippodrome
  Figure 22
  
  P.1. Ground Plan 1: 1st half of 2nd and 3rd cent., 1st phase: construction and primary use of circus – chariot racing
  
  (A.O.1995)
  
  Ostrasz and Kehrberg-Ostrasz (2020)
  (2nd and 3rd centuries CE) from Ostrasz and Kehrberg-Ostrasz (2020)
• Fig. 19 - E-W cross section of
  Figure 19
  
  Schematic cross-section of hippodrome (A.O.1992)
  
  JW: Note varying thickness of uncompacted fill which would likely to lead to differential settlement
  
  Ostrasz and Kehrberg-Ostrasz (2020)
  Hippodrome showing potential foundation problems from Ostrasz and Kehrberg-Ostrasz (2020)
• Fig. 4 - Tumble layer
  Fig. 4
  
  Carceres.
  
  East half.
  
  Lowest stratum of tumble
  
  JW: Note uniformity of tumble where collapsed arches appear visible
  
  Ostrasz (1989)
  from mid 8th century earthquake from Ostrasz (1989)
• Fig. 21 - Perspective
  Figure 21
  
  Perspective view of part of carceres
  
  (A.O.1992)
  
  Ostrasz and Kehrberg-Ostrasz (2020)
  view of part of carceres from Ostrasz and Kehrberg-Ostrasz (2020)

• from Ostrasz and Kehrberg-Ostrasz (2020:402)

Figure 184

Schematic Chronological chart of the Hippodrome complex showing phases of primary use and secondary occupancies

Ostrasz and Kehrberg-Ostrasz (2020)

• from Ostrasz and Kehrberg-Ostrasz (2020:17)

• General Plan of Jerash
  Plan of Jerash. North is to the right.
  
  Holger Behr - Wikipedia - Public Domain
  from Wikipedia
• Fig. 22 - Plan of hippodrome
  Figure 22
  
  P.1. Ground Plan 1: 1st half of 2nd and 3rd cent., 1st phase: construction and primary use of circus – chariot racing
  
  (A.O.1995)
  
  Ostrasz and Kehrberg-Ostrasz (2020)
  (2nd and 3rd centuries CE) from Ostrasz and Kehrberg-Ostrasz (2020)
• Fig. 19 - E-W cross section of
  Figure 19
  
  Schematic cross-section of hippodrome (A.O.1992)
  
  JW: Note varying thickness of uncompacted fill which would likely to lead to differential settlement
  
  Ostrasz and Kehrberg-Ostrasz (2020)
  Hippodrome showing potential foundation problems from Ostrasz and Kehrberg-Ostrasz (2020)

Maps, Plans, and Figures

That the structure was destroyed by an earthquake is evident from the position of the fallen stones in the lowest layer of the tumble; nothing but an earthquake could make the masonry fall so. The amount of the fallen stones in the whole tumble shows that most of the masonry of the structure fell northward, onto the arena. Moreover, there is also evidence for the process itself of the fall. In this respect it has to be noted first that the standing remains of the carceres, that is to say the piers between the stalls, all stand at least two, but none more than three masonry courses high (originally the masonry of the stalls consisted of thirteen courses). Some stones in the standing masonry are slightly shifted from their original position but none was noticed to have lost its verticality. In all, the lowest parts of the masonry of the piers were little affected by the earthquake.

The case of the upper parts (originally seven masonry courses high, the course of the imposts of the archivolts included is different. Only one pier (3E/4E) of the east stalls provides full evidence for how its masonry collapsed but it can be maintained (infra) that its example is representative of the situation which, during the earthquake, was found also in the case of the others. All the stones but one of the four upper masonry courses of the north face of the pier (stones 73-82) were found in the tumble. The stones of courses 4-5 (lower) fall closest, immediately against the face of the pier, the stone of course 6 (higher) slightly further from it, and the two stones of course 7 (uppermost) yet further from the pier. The pattern of the falling of the stones of this particular pier is clear. The higher the position of the stones in the masonry the further from the pier they fell. A similar pattern is noticeable in the position in the tumble of the three stones identified of pier 4E/5E (stones 84 - course 3, and 90-91 - course 7) and there is an identical pattern in the tumble of stones of the north face of pier 4W/5W (stones W113, W132, W133-135, W137, courses 4-7). This pattern indicates that the earthquake disturbed fatally not only the static balance of the structure but that it also created the force which projected the masonry (particularly its whole northern vertical layer) forward that is to say northward.

This projecting force is best evidenced by the tumble of the masonry which made up the upper part of the north façade of stalls 1E-4E (courses 8-13, from the level of the spring stones of the archivolts to the level of the crowning cornice). While in place, this part of the façade was about 23m long and 3.3m high, and its surface was about 75m². After the fall, it covered an area of almost the same length, width (former height) and surface. In the process of falling, it described in the air a curve very close to a quarter of a circle of which the radii of the particular masonry courses were approximately concentric and of which the centre was approximately at the level and face of the top of course 3 of the piers. While the masonry of the north façade stood intact, the top of the comice course was 5.4m, the apex of the archivolts 3.6m and the spring stones of the archivolts were 2m above that level. After the fall, these elements lay at a distance of 5.5 - 6.5m, 4 - 4.4m and 2 - 2.5m, respectively, from the façade. Figuratively speaking, the whole vertical layer of the masonry making up the north façade fell from the vertical to the horizontal position just as a solid platform of a drawbridge would fall, its hinges being at the level of about 2m above ground.

Two factors contributed additionally to this pattern of collapse for which the earthquake was, of course, instrumental. One was the tectonics of the piers and especially of the upper parts of the carceres. As all other parts of the hippodrome, they were built of dressed stones on the outside while the inside was filled with boulders and stone chips set on earth. In consequence, the masonry was not cohesive in its entirety; a slightest disturbance of the static stability of the structure could (and did) immediately detach the dressed stone facing from the inner `core' of boulders, stone chips and earth. The other factor was the physical condition of most stones in the lowest courses of masonry of the piers. As in the case of the lowest courses of masonry in most parts of the hippodrome, these stones deteriorated in a much greater degree than the stones of the upper courses (for the reasons cf. infra:...). They lost most of their resistance to pressure of the masonry above; any movement of the structure combined with the pressure of that masonry could not fail to make them disintegrate instantly.

All the above considered, the process of collapse can be reliably reconstructed. The earthquake caused the structure momentarily to lean forward (northward). In that instance and in that position two things occurred simultaneously: the force of gravity made the masonry of the north façade detach itself from the inner core and the deteriorated stones making up the lower courses of the face of the piers gave way, as the support for the upper parts of the façade. In this situation the masonry could not fail to collapse. However, the gravity force alone could have made the stones of the masonry fall roughly vertically and in a rather haphazard order. They did not fall so. Instead, they described in the air a part of a circle and fell `orderly' and far from their vertical position. This shows that apart from the force of gravity there was another force, the force which catapulted the stones first horizontally before the force of gravity `pulled' them down onto the ground. This ejecting force must have been created in the moment of leaning of the whole structure forward and this shows in turn the leaning occurred instantaneously and violently.

Considering the fact that the structure fell northward it must be assumed that during the earthquake the ground under the structure moved upward at its south side and/or downward at its north side in a split second and with a great force (speed). That movement made the structure lean violently which created the force catapulting the stones forward. This force naturally increased in direct proportion to the height of the structure as is clearly witnessed by the position on the ground of the fallen masonry of the upper parts of the north façade of the carceres. To make it all happen as it happened, the earthquake must have been extremely strong.

The fallen stones show the direction of fall of the carceres. It has been observed that `During an earthquake the columns, pilasters, and walls of structures have a tendency to collapse in the opposite direction of the quake's epicenter or hypocenter.' (Russel 1985: 51-52) Accordingly, the directional pattern of collapse of the carceres indicates that the epicentre or hypocentre of the earthquake which destroyed the structure was to the south of Gerasa. The reconstruction of the process of the collapse points to a forceful earthquake. The recent studies of the earthquakes in the region of Palestine and northern Arabia from the 2nd throughout the 16th century elucidate the stronger and weaker earthquakes known in that period and region. Accordingly, both phenomena - the directional pattern of collapse and the strength of this earthquake - are, then, additional evidence (beside the deposit sealed by the tumble) for dating the occurrence (infra).

The stone tumble contained no ceramic or coin deposits. It was only the excavation of the top layer of the ground underneath the tumble that yielded the ceramic and coin material (Compendium B: Kehrberg 1989, 2004 and 2016a). The surface of the ground sealed by the tumble in front of the stalls was about 140m² (about 7m by 20m). This surface was not level, that is to say it was not the original top surface of the arena.

... Ceramic deposit. (see Compendium B: Kehrberg 1989-2006, fc 2018)

Stm.2, Stm.3, and possibly Stm.1 - 1600 potsherds, 2 intact lamps and 62 lamp fragments. Most pieces are fragmentary and worn, especially the lamp fragments. A very small proportion of the material (%)²⁰ dates from the lst throughout the 3rd century, the bulk (%) dates from the 4th throughout the 6th century, and the remainder (%) dates to the 7th and 8th centuries. In the first group, the proportion of the sherds and lamp fragments dating to the 3rd century is the least. In the second group, the proportion of the material dating to the 4th, 5th and 6th centuries was found to be roughly equal, respectively, and so was the material in the third group dating to the 7th and 8th centuries.

Finally, the excavation yielded evidence for dating the collapse of the carceres. The latest potsherds and lamps found in the area sealed by the tumble are of the Umayyad period. The latest coin underneath the tumble is datable to the first half of the 8th century. The sealed deposit contained no artefacts of a later date. Of all the material, the coin provides the relatively strictest terminus post quem for the destruction of the carceres - the first half of the 8th century. The terminus is based on the evidence ex silentio of the material of a date later than of the first half of the 8th century, but this evidence can securely be accepted as reliable considering other parts of the monument (supra....).

Maps, Plans, and Figures

The archaeological context of the excavated sections of the cavea was found to be the same almost everywhere. On the outside of the remains of the outer and podium walls, and contiguous to them, was the stone tumble of the upper parts of the walls. The inside of the chambers was filled mainly with the tumble of the stonework of the cavea proper (seat stones and voussoirs of the stepped arches which supported the seating tiers) and with a number of stones of the outer wall. In many chambers the position of the stones displayed clearly that the stonework collapsed during an earthquake. The tumble was subsequently quarried for stone. The quarrying was very extensive; only a small proportion of the stones which made up the particular parts of the masonry was left in the tumble. The parts of the masonry which survived the disaster were also robbed of stones.

The stratigraphy of the fill in the chambers was very simple. In most chambers there was only one stratum (from 2 to 4 m thick) over the `floor' level: masonry tumble composed of dressed stones, boulders and rubble, all immersed in earth. <sup>7</sup> The tumble lay directly on the `floor' which in chambers E40-E55 is the unlevelled surface of rock and in all others the top of the fill within the foundation walls of the chambers. The fill itself is another, the lowest stratum. Is is composed of thick layers of earth and thinner and irregular layers of stone chips. In some chambers there was an intervening thin layer of earth and rubble between the top and bottom of the two strata mentioned above. The tumble outside the outer wall lay on top of a residual layer from 0.3 m to 0.8 m thick. Underneath, there is the same kind of earth with which the space within the foundation walls of the chambers (and the arena) is filled. The masonry tumble outside the podium wall lay directly on the surface of the arena ⁸.

The archaeological context of the carceres was very similar to that of the cavea. On both sides of the remains in situ and contiguous to them, as well as inside the staffs, there was the tumble of the upper parts of the masonry destroyed by an earthquake (fig. 4). Most of the masonry collapsed northwards, on to the arena. The bulk of the tumble was not disturbed by quarrying for stone and every stone retained its tumbled position. The tumble lay on the surface of the arena.

Footnotes

8 Except the middle section of the east part of the building where the tumble lies on the slope of the depression.

The excavated sections of the hippodrome displayed clearly that the building was finally destroyed by an earthquake. The best attested examples were found in the carceres, in chambers E40-E43 and E25-E28 (currently under excavation), and in the neighbouring church of Bishop Marianos. The coins and the ceramic material from the deposits sealed by the tumble provided evidence for dating the occurrence. No material dating beyond the Umayyad period was found in any of the deposits. The latest coin from the deposit under the tumble of the carceres is datable to the first half of the eighth century and the latest ceramic material found in it dates to the eighth century (Kehrberg 1989: 88). The latest coins recovered from under the tumble in chambers E40, E41, E42 and E43 were minted in 383-395, 498-518, 575/6 and between 527 and 602, respectively. The latest pottery, lamps and lamp fragments from the same deposits date to the seventh century. The only coin found under the tumble of the church of Bishop Marianos was minted in the first half of the eighth century and the objects are dated to the same period (Gawlikowski/Musa 1986: 149-153).

The finds prove that the south-east part of the cavea stood high in the seventh century and the carceres and the church still stood high in the first half of the eighth century. The lack of material dating after the middle of the eighth century shows that this part of the building was either abandoned or destroyed at, and never occupied after, this date. The archaeological context of the finds in the church clinches the matter. It shows that ...the church remained in use to its end. (Gawlikowski/Musa 1986: 141), that is until the earthquake which must then have occurred about the middle of the eighth century.

Only one earthquake is securely attested in the region of ancient Palestine in the eighth century and this is the earthquake of 748 (747) (Russell 1985: 39, 47-49). It is also well attested at Jerash (Bitti 1986: 191-192; Crowfoot 1929: 19, 25; id., in Kraeling 1938: 221, 242, 244; Parapetti 1989a: passim; Parapetti 1989b: passim; Rasson/Seigne 1989: 125, 151; Seigne 1986: 247; Seigne 1989: passim). The hippodrome of Gerasa is yet another well attested example of that disaster.

Ostrasz, A. A. (1989) The Hippodrome of Gerasa: a report on the excavations and research 1982-1987', Syria. Archéologie, Art et histoire 66-1-4 pp. 51-77

Ostrasz, A. A. and I. Kehrberg-Ostrasz (2020). The Hippodrome of Gerasa: A Provincial Roman Circus, Archaeopress Publishing Limited.

Photos of Jerash Hippodrome at wikimedia commons