Hydraulics

A recurrent theme throughout the 1998 excavation season was water. As the reconstruction plan of the pool in figure 19 illustrates, an elaborate water distribution system incorporated into the construction of the pool. In addition to its role as a retaining wall for the pool, the East-West Wall functioned as an aqueduct, transporting water in channels and pipes to a central holding tank and redistribution point. The aqueduct was apparently fed from the east by a V-shaped water tank perched on top of the eastern escarpment (see site plan). The interior walls and floor of the tank are lined with the same concrete as that lining the pool's interior. Narrow channels and ceramic pipelines transported water across the top of the East-West Wall (fig. 16, above).
fig. 8 (left) - Cutaway view of the island-pavilion based on evidence obtained during the 1998 season (by C. Kanellopoulos).
fig. 9 (above) - Aerial view of pool and island-pavilion (from the same angle as fig. 8) at the end of the 1998 season.
Excavation Results

Excavations focused mainly on the southern half of the 'Lower Market' where the only substantial architectural features were visible at the surface. Trench 1 was laid out to expose the northwest quarter of the rectangular structure located at the center of the plateau, north to the East-West Wall. A major clearing effort was conducted along the west half of the East-West Wall while Trenches 3 and 4 revealed important features at the center and further east along the wall. Trench 2 provided limited exposure of a stone wall at the center of the earthen terrace (see site plan).

The unexpected result of the 1998 season was the discovery of a monumental
open-air pool (interior dimensions: 43 m x 23 m x 2.5 m) with island-pavilion that
occupies the entire southern half of the "Lower Market". It was determined that
the 'Lower Market' was not, in fact, a marketplace, but the site of a luxurious
pool-complex, most likely associated with a formal garden.


Island-Pavilion

The island-pavilion is rectangular in plan (11.5 x 14.5 m) and open on at least three sides (fig. 8). The front (northern) doorway measures 4.6 m across, occupying almost half of the façade's width; the two lateral doorways each measure approximately 3 m in width. All three doorways have double-recessed frames, a feature found on many of the Assyrian-type tomb façades in Petra. It is possible that the pavilion was open on all sides, with an fourth doorway located in the rear (southern) wall.
fig. 8 (left) - Cutaway view of the island-pavilion based on evidence obtained during the 1998 season (by C. Kanellopoulos).
fig. 9 (above) - Aerial view of pool and island-pavilion (from the same angle as fig. 8) at the end of the 1998 season.
The pavilion is founded on a rectangular pedestal--a solid foundation of tightly packed sandstone bonded with a white impervious mortar--2.5 m high (fig. 10). Water was prevented from seeping into the structure through its submerged foundation by lining the exterior with a thick coat of concrete, the same concrete that lines the interior wall and floor of the pool. The walls of the pavilion, which are preserved three to five courses high, are constructed of two rows of sandstone blocks bonded with impervious mortar. In addition, the interior floor of the pavilion was covered with a thin layer of white plaster topped by a thick layer of water-resistant gray mortar made from a mixture of lime and ash. At one time, the floor was originally covered with rectangular pavers that were robbed out in antiquity, leaving their impression in the underlying lime-ash mortar (fig. 11). A channel cuts diagonally across the floor and connects with another channel that encircles the exterior perimeter of the pavilion, just above the maximum water level of the pool (fig. 10). It is likely that this exterior channel was originally capped and functioned as an overflow channel between the pavilion and the pool (see fig. 8, above).
A single sandstone pedestal stands in the interior of the pavilion, near the western lateral doorway (fig. 11). The sides of the pedestal are pitted with deep holes, many still imbedded with iron fragments.  Such "attachment holes" were used to anchor plaster to the vertical surfaces to prevent slumping. Remnants of plaster and light gray marble paneling are preserved around the base. This pedestal is most likely one of four column pedestals arranged symmetrically around in the pavilion's interior and spanned by wooden beams to support the roof structure. The general absence of roofing material in Trench 1, may be considered evidence against a pitched roof design (there is no evidence for an entablature and only a few roof tiles were found in later fill). A flat, earthen roof, much like that proposed for the contemporary temple, Qasr el-Bint (McKenzie 1990:Pl.68b) must be argued ex silentio in lieu of further excavations. Based on the width of the front doorway, a minimum proportional height of 10 m (above floor level) is proposed for the pavilion (fig. 8, above).
Several fragments of marble capital, including two volutes were found in the fill around the column pedestal and may be from a corinthian capital that topped the column (fig. 12). Also found in the vicinity was a unique five-petaled marble flower in high relief (fig. 13). Numerous fragments of worked limestone and marble (capitals, tiles, inlay, moulding), some of non-local origin, testify to the investment given to the elaborate adornment of this unique building. A small patch of white lime plaster in the northwest corner is all that is preserved of the interior wall decoration. Several fragments of painted stucco --dark red, orange, and bright blue--and fragments of stucco moulding with dentils (fig. 14), were found in the fill and give some indication of the décor and color scheme inside the pavilion.
fig. 12 - Marble volutes, probably from a corinthian capital, found inside  the pavilion..
fig. 10 - The  north façade of the island-pavilion, looking south. In the foreground is the south pier of the bridge, vault springers visible just above the line of unexcavated fill. The deep probe in the lower right corner was excavated down to the pool's floor, 2.5 meters below the surface.
Pool

The East-West Wall functioned as a dam across the site transforming the quarried-out space to the south into a large reservoir or pool (fig. 15). Clearance of earth and rubble from the East-West Wall revealed a monumental construction 2.2 m high and 3.5 m wide. The exterior faces are made up of close-fitting sandstone ashlars typical of Nabataean masonry (much of the north face is robbed out); between them is a solid construction composed of alternating rows of roughly hewn sandstone blocks and rubble bonded with an impervious white mortar (fig. 16). The south face of the East-West Wall--the interior of the pool--is lined with a thick coat of concrete (fig. 17) such as is typically used to line the reservoirs and cisterns found
fig. 16 - The East-West Wall with "west channel", looking east.
fig. 15 - Aerial view of pool with island-pavilion as they appeared after the 1998 season (north is at top).
fig. 17 - The interior north-
west corner of the pool with concrete lining.
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Unless otherwise indicated, all photos, illustrations and text on this site
by Leigh-Ann Bedal ©1999. All rights reserved
Last updated: February 2000
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fig. 11 - Interior of the island-pavilion, looking north. The impressions of robbed out pavers are preserved in the floor.
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fig. 13 - Front and side views of a marble flower found  inside the pavilion.
fig. 14 - Fragments of moulded stucco with dentils
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in many Nabataean settlements (Hammond 1967) and described by the ancient Greek historian Diodorus Siculus (19.94.7). The northwestern and northeastern corners of the pool were located 43 m apart, equidistant from the site's central north-south axis. The top four steps of a staircase leading to the pool's floor were uncovered in the northeastern corner (fig. 18). Four rectangular pavers found in situ along the eastern edge of the pool (fig. 18) are the only evidence for a nicely paved promenade around the pool's perimeter.
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fig. 18 - The northeast corner of the pool with staircase and pavers, looking north. Channel with impression of two parallel pipelines is at top.
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Hydraulics

A recurrent theme throughout the 1998 excavation season was water. As the reconstruction plan of the pool in figure 19 illustrates, an elaborate water distribution system incorporated into the construction of the pool. In addition to its role as a retaining wall for the pool, the East-West Wall functioned as an aqueduct, transporting water in channels and pipes to a central holding tank and redistribution point. The aqueduct was apparently fed from the east by a V-shaped water tank perched on top of the eastern escarpment (see site plan). The interior walls and floor of the tank are lined with the same concrete as that lining the pool's interior. Narrow channels and ceramic pipelines transported water across the top of the East-West Wall (fig. 16, above).

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Positioned along these channels are shallow basins--one at each corner and one 4 m east of the holding tank--that acted as filters for sand and silt as the water passed through. In addition to the narrow channel described above, the east half of the East-West Wall had a much larger channel in which two parallel pipelines were installed. Although no pipes were found, their rounded impressions were preserved in the concrete lining on the floor of the channel
(fig. 18, above, and fig. 20)
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Excavations in Trench 3 uncovered a central holding tank built into the wall immediately east of its central axis. All of the conduits in the East-West Wall--the east and west channels and the double pipeline--converged at this point and emptied into the holding tank, or castellum divisorium, where water  was collected and then redistributed (figs. 20, 22 and 23). That the castellum was originally roofed is indicated by the remnants of a supporting arch springer mid-point on its south wall. Immediately to the west of the arch springer is an overflow passage (60 cm high x 80 cm wide) that originally allowed water to pass between the castellum and the pool. At some point, this passage was sealed, probably at the time of the construction of the bridge (see below) which would have blocked the passage.
fig. 19 - Plan of pool and hydraulics; blue lines = stone water channels; orange lines = ceramic pipelines.
fig. 20 - The castellum (bottom) fed by a large channel once installed with two ceramic pipelines, looking east.
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Three postholes near the southeast corner of the castellum, may have secured a lever or sluice gate used to control the flow of water into the tank (fig. 21). Water exited the castellum through a hole near its base and was fed into stone channels which run north and northwest, underneath a pavement that is laid out along the southern edge of the earthen terrace (figs. 22 and 23).
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figs. 22 and 23 - The castellum and redistribution conduits, looking south (far left), and from above looking north (left). The water exited the castellum through a hole in the base
of the north wall and was distributed northward across the earthen terrace in stone channels located underneath the pavement.
Based on the presence of a monumental pool with island-pavilion and an elaborate system of water conduits converging onto the earthen terrace, these channels may best be interpreted as part of an irrigation system for a garden, which occupied this large, flat unbuilt space. In other words, instead of functioning as a hub of economic activity, the so-called "Lower Market" was apparently a formal garden, a place of refuge within the city's civic center. One of the goals of future excavations seasons will be the systematic study of the earthen terrace aimed at uncovering important details about the general layout of the garden and the varieties of plants cultivated there.
The Pool-Complex at Petra
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