The Middle PPNB settlement of Beidha is situated on small terrace overlooking a small wadi system that today supports dry farming (Fig 2). Beidha was excavated during eight seasons of work between 1958 and 1983 during which time ca. 1,500 sq m of Neolithic deposits were exposed. Recent re-analysis of the stratigraphy distinguished three phases of occupation: the earliest (A) identified by the presence of circular stone buildings, followed by Phase B consisting of sub-rectangular stone buildings, and finally the latest occupation (C) defined by stone corridor buildings [20]. New excavations were conducted during 2014 with permission from the Jordanian Department of Antiquities to investigate one large Phase A structure, Building 37.

Based on previous and new radiocarbon determinations obtained from Phase A and contexts associated with Building 37, this structure was in use during the early MPPNB (ca. 8000 cal BC). Radiocarbon determinations associated with Building 37 include two charcoal samples, one obtained from a layer of collapsed structural material (141) (Poz 67013, evergreen oak, 8760± 50 uncal BP, 8166–7602 Cal BC at 95.4%) and the other from a layer of compacted, probably trampled material (109) (Poz 67011, Pistacia sp., 8770± 50 uncal BP, 8170–7609 Cal BC at 95.4%). Both samples were retrieved from above the burnt roof material and from contexts possibly deriving from the collapse of the wall. The third charcoal sample (Poz 67010, Quercus sp., 8720± 50 uncal BP, 7939–7601 Cal BC at 95.4%) is derived from the sterile sand (103, described below) underlying the Building 37 floor. These three samples yielded similar radiocarbon determinations dating to the early part of the MPPNB (8170–7601 cal BC, 95.4% probability), while the fourth date obtained from a piece of oak charcoal (Poz 67014, 8860± 50 uncal BP, 8224–7795 cal BC at 95.4%) retrieved from the fill of one of the postholes (126) located below the stone sub-floor sand was fractionally older, but still MPPNB in date. All dates are modeled in OxCal v.4.2, using IntCal13 calibration curve [36, 37].

Building 37 is part of the earliest (Phase A) occupation of Beidha which is broadly dated to the early MPPNB and divided into two sub-phases A1 and A2, although four phase A buildings cannot be separated into either sub-phase (Fig 1; [20]). Phase A architecture, previously described as ‘domestic dwellings’ [20], consists of circular semi-subterranean stone structures replete with post-sockets set along the interior face and, in most cases, a single central posthole. Phase A circular buildings range in size between 2m2 to 14m2 in area, with the interior floor area ranging between 1.7 m2 and 5.0 m2 for ‘small’ buildings (mean = 3.9 m2) and 7.4m2 to 14.9m2 for ‘medium’ buildings (mean 10.6 m2) [38]. Phase A buildings were laid out in tight clusters, frequently shared walls, and often had more than one entrance, although remodeling of the wall circuits and blocking of doorways suggests that only a single entrance may have been in use at any one time.

The six subphase A1 buildings lacked internal features other than a posthole, but contained rich inventories of in-situ material culture, including bitumen baskets, wooden bowls and boxes, bone tools, stone bowls, querns, pestles, groundstone axes, and shell beads set on floors [20]. Some of the eight sub-phase A2 domestic buildings lacked a central posthole hole, but several contained a single feature (e.g. a hearth set into a plaster floor or a raised stone platform); smaller in situ material inventories were also present on floors.

Phase A architecture was regularly repaired and modified, with new floors laid down, walls buttressed, and overall building configurations modified during their occupation. A2 constructions frequently re-used phase A1 building walls and it is possible that two subphase A1 buildings were continuously used into subphase A2, increasing the architectural density of the cluster of domestic structures. Several of the A1 buildings and two-thirds of the A2 buildings were destroyed by fire, evidenced by collapsed roofs containing considerable carbonized material including central posts, roof beams, and heavily burned roof clay imprinted with beams and reeds. Previous interpretations have attributed the burning to a single catastrophic fire that precipitated large-scale abandonment of the settlement [20]. However, recent experimental work at Beidha indicates that burning of Phase A type buildings requires a significant amount of effort to ignite and maintain, suggesting that firing buildings was an intentional activity and part of the formal process of closing structures [39].

The only human interments associated with Phase A are from subphase A1 Building 41, only a quarter of which was excavated. Seven individuals were interred in midden deposits that accumulated within the abandoned building as part of a succession of separate burial events, some of which disturbed earlier interments. Young adults, young children, and newborns all received burial treatment and were arranged in flexed and semi-flexed positions (McClelland unpublished report). Some individuals were placed on flat stone slabs (e.g. infant burials 3 and 7) or their head propped up on a ‘pillow’ stone (e.g. burial 5, five year old child). Notably, all buried individuals retained their cranium.

Kirkbride’s excavation of Building 37 also revealed a floor composed of tightly packed irregularly shaped stones with at least one flat surface. The spaces between flooring stones were originally described as filled with gravel and no mention of a clay or plaster surface covering the flooring stones, although there is somewhat contradicting information reported mentioning the presence of a ‘thin layer of clayey occupation debris’ directly on the floor ([ 20 ]: 37). The original excavations also identified a stone lined posthole, ~ 50cm in diameter with a base ~ 75cm below the floor, in Building 37 and plaster of an unknown material preserved around the post itself. A series of large stone slabs sitting directly above the floor was also identified. Protruding from the western section profile, these slabs were interpreted as a platform that had collapsed onto the floor. One slab was originally described as being quite large (1.5 x 2.0m) size, but pictures and horizontal plans from the original excavations indicate a much smaller stone 1m x 50cm in size that remained partially covered by unexcavated deposits ([ 20 ]: 265–266).

During the Kirkbride excavations, a passage entrance that extended beyond the perimeter of the exterior of the primary Building 37 wall was identified on the east side of the structure ( Fig 2 ). Two threshold stones were also uncovered, evidenced in the original excavation photos although not discussed in the original excavation report. This entryway was later modified and turned into a small alcove which appears to have differed in construction from the rest of Building 37 according to Kirkbride’s original photographs, distinguished by small cobbles in the one-course wide wall construction and absence of wall-post-sockets. Although it is unknown if this alcove wall was removed during original excavations or collapsed later on after exposure, the absence of any remaining traces of the alcove wall suggests it was not bonded to the original construction and the alcove was a later installation that blocked the passage entryway. The alcove was later partially blocked with additional stone cobbles.

In addition to the domestic buildings identified in phase A, an unusually large, circular structure, Building 37, was partially uncovered during the excavations conducted during the 1950s and 60s. Located on the westernmost edge of the site alongside the edge of a wadi that runs along the settlement ( Fig 2 ), Building 37 was originally described as a large circular building ca. 6.2m in diameter constructed of large unmodified cobbles with the interior stone face lined with vertical post-sockets inset into the wall. At the time, it was thought that half of the structure had been excavated based on the estimated interior curvature of the Building 37 wall. Building 37 was interpreted as a structure that stood slightly apart from all other buildings in the settlement based on the absence of architecture abutting the exterior eastern and southern portions of the wall face.

Renewed excavations of Building 37

In light of recent research indicating the prominent role of communal buildings in structuring the earliest Neolithic societies in southern Jordan, we renewed excavations of the Building 37 in order to better 1) delineate the overall structural form and internal features, 2) document the construction history and 3) establish the chronology of construction and use of the building. Beidha is a part of the Petra World Heritage site, and the extent of the new excavations was tightly controlled in order to minimize its impact on remaining deposits and maintain the site and building for display. Renewed excavations revealed that Building 37 is distinguished from other contemporaneous phase A architecture by the manner in which the a) building site was prepared for construction, b) way in which Building 37 stood slightly apart from the other tightly grouped buildings, c) construction of a floor designed for heavy use as well as evidence for intensive use of the floor, d) presence of a group of shaped stone slabs in the building (although this is not unique–Building 54, for example, has a series of slabs set into its floor), and e) its large size. At the same time, Building 37 shares numerous features with other Phase A buildings, including a lack of interior divisions, passage entryways, and later blockage of entryways with stone cobbles.

The new excavations reveal that the site for Building 37 had been carefully prepared before the building was constructed. Although not explicitly mentioned by Kirkbride, examination of photographs suggests a foundation pit was excavated for Building 37 indicated by the difference in height between the stone surface in the building and the contemporaneous ground surface visible through the original entrance (pre-alcove) located on the east side of building of the interior stone floor ([20]: plate 173). The new excavations indicate that the pit reached, and may have truncated, an earlier occupation layer represented by post- and stake-holes cut into a layer of compact sand with a high ash content (Context 119). This occupation layer was overlain by ca. 10 cm of sterile sand (Context 103) which apparently functioned as lining of the presumed foundation pit prior to the construction of the Building 37 wall and floor. Outside of forming a level surface at the base of the pit, the sterile sand would not have provided any additional structural benefits to the building.

An unusually well-constructed and robust floor designed for heavy use was installed in Building 37 with the robust circular wall identified during Kirkbride’s excavation, here named Wall 1. The new excavations revealed that this floor (Context 149) consisted of a 1cm thick, extremely compact sterile clay material worked in between and over tightly packed small, flat stones (Context 148) which mortared the stones together to create a smooth surface (Fig 3). The flat stones, originally interpreted by Kirkbride as the floor surface [40], instead served as a sturdy foundation for the clay that formed the actual floor surface. It is clear that the extremely compact clay is not occupation debris as described in the original report as it contained no cultural material or ash. Patches of gravel (context 157), also identified by Kirkbride, were also placed on some areas of the stone surface, probably to level uneven areas of the stone sub-floor before the clay surface was laid down.

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larger image TIFF original image Download: Fig 3. Building 37 floor surface and subfloor. View of Building 37 clay floor laid over tightly packed smaller stones. Bare patches located in the northern quadrant of the clay floor reveal the foundation stones underneath and suggest the clay surface was worn through from heavy use. https://doi.org/10.1371/journal.pone.0193712.g003

This robust floor design, not present in any other phase A structures which instead contained thin plastered floors, appears to have accurately anticipated intensity of use. Notably, the clay floor surface was not present in some areas, particularly in the northeastern portion of the building, leaving the foundation stones (148) exposed (Fig 3). The clay surface thinned out around these bare patches of stone surface, suggesting these patches were places where the floor wore out from repeated use.

Renewed excavations revealed a second substantial post-hole (context 150) inside Building 37, 35cm in diameter and 40cm deep, well-lined with flat elongated stones firmly wedged in with chocking stones; the carbonized remains of an upright timber were also identified in this posthole. Building 37 was apparently sufficiently large that its roof required two posts to hold it up, contrasting with the single post-holes found in other Phase A buildings.

No internal architectural features other than the post-holes were present in Building 37, but other, possibly portable, features were identified. The stone platform initially exposed in the 1960s was fully excavated revealing two large slabs (context 153 and 154) and a smaller slab (context 159), which lay between the larger stones, together forming a tight, overlapping group (Fig 4). All the slabs are made of local sandstone and are ca. 2cm thick. One slab (context 153) displays a series of incisions cut along its northern edge, almost identical to the incisions found on a stone slab at the nearby MPPNB site of Shkarat Msaied, there used as part of a stone burial cist in Building F ([27], 70, and Fig 2.48 p 365). The western end of the same slab had been flaked to produce a straight edge, while its eastern end was shaped in a convex form, making the slab similar in overall shape to the slab from Shkarat Msaied described as a stele ([27], Fig 2.52, p 368). Slab (context 154) had been flaked on its eastern end to produce a straight edge while its opposed, western end had been flaked into the shape of a truncated triangle. The smaller slab (context 159) had been shaped to produce the same form as (context 154), but lay with its straight edge to the west.

It is highly unlikely that these slabs in Building 37 functioned as a platform as initially thought during the original excavations. A very thin (<1cm) layer of clean sand (Context 158) was identified between the surface of clay floor 148 and the stone slabs, and, a few stones were wedged under some slabs. This suggests the slabs were laid carefully onto the clay floor with some protection and stability created by the sand deposit and wedging stones. The careful shaping of the slabs and the presence of a straight edge on all three of them may indicate they were originally intended to stand upright, perhaps to form a small feature such as the cist at Shkarat Msaied building F. The slabs are too thin to have stood on their own, and equally, would have been too fragile to have formed a functional platform surface. The slabs would have been relatively portable, and easy to support with clay buttressing, or even bound together with rope. A concentration of baked clay above and around the slabs was identified during excavation, but it was difficult to discern if this was detritus from roof collapse or was directly associated with the stones. It may be that the slabs were intentionally, and carefully, placed on the floor of the building before it was burnt down. While it would be facile to assume a ritual role for such shaped slabs, their similarity in material, shaping, and cut marks with slabs from Shkarat Msaied employed in mortuary architecture, suggests that they had some symbolic connotation.

An isolated stone slab (context 152) was also found near the newly excavated post-hole (context 150), which was situated on a thin layer of ashy material (context 146). Below this ash, another slab of approximately the same size and shape as stone 152 embedded in the clay floor (149) was identified. The upper slab appears to have been put in place to mark the location of the lower slab very soon after the roof burning took place, possibly even during the course of roof collapse, as it was buried below the main layer of charred timbers.

Complete excavation of Building 37 revealed that the structure was not circular in shape as anticipated by Kirkbride (Fig 5). Instead, the renewed excavations indicate that that the original building ground plan was initially oval in shape, with its long axis running east-west, so the original interior area would have been considerably greater than initially assumed by Kirkbride (Fig 6). Moreover, the new excavations revealed that the western portion of the wall section was not part of the original Building 37 wall construction (Wall 1), but a later addition. This later wall (Wall 2) addition was constructed using the same methods used in the original wall and other Phase A domestic architecture (i.e., a thick stone rubble wall with post-slots present on its interior face), but unlike the original Wall 1, this later wall addition was not semi-subterranean. The later Wall 2 addition also sits on a different alignment to the original Wall 1. This is most clearly visible where Wall 2 springs off from the southern part of the original wall line at an angle much sharper than the expected curvature the original wall should have followed if it was to create a symmetrical elliptically-shaped building (Fig 5); the later wall addition meets the northern part of the original wall at a similarly sharp angle. Further evidence that Wall 2 was a later wall addition is found in the section profile that cross-cuts the southernmost edge of the original wall. Here, remnants of collapse originally from the western section of the original wall are visible; the rest of the original wall likely fell in to the eroding wadi (Fig 7). A second entryway and accompanying threshold stones were also identified in the southwestern portion of Wall 2; this entryway was not blocked (Fig 8).

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larger image TIFF original image Download: Fig 5. Horizontal plan of Building 37. Ground plan of new excavations indicating positioning of stone slabs, stone-lined posthole, and posthole identified during the Kirkbride excavations (grey circle). Arrows indicate contact between original Wall 1 and later addition Wall 2. https://doi.org/10.1371/journal.pone.0193712.g005

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larger image TIFF original image Download: Fig 6. Sub-floor deposits in Building 37. Overhead view of Building 37 after removal of the clay floor surface (eastern half of structure) and sub-floor paving stones (western half of structure). Deposits and features visible under the sub-floor paving stones are pre-Building 37 and include packed ash layers, shallow pits, and several postholes. Note the close proximity of the wadi on the west side of the Building 37; sediments in between Wall 2 and the wadi edge are largely overburden from the original Kirkbride excavations. The linear arrangement of stones west of Wall 2 were placed to define the edge of the excavation trench for tourists. Further to the west, rectilinear stones are a modern stairway also for tourist use. https://doi.org/10.1371/journal.pone.0193712.g006

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larger image TIFF original image Download: Fig 7. Wadi edge outside Wall 2. View of the steep slope into the wadi contemporary with Wall 2. The angle of slope makes it clear this wall is not in a semi-subterranean position, and is exposed to erosion. https://doi.org/10.1371/journal.pone.0193712.g007

Maintaining the size of Building 37 after the partial collapse of Wall 1 was clearly important. Even after the installation of Wall 2, the building was extremely large exhibiting a maximum north-south dimension of 6.5m, and east-west 7m, with an internal area of ca. 35m2. This is more than double the size of the next largest Phase A building and three times the mean interior area of all Phase A architecture (ca. 10m2).

However, the alignment of the new wall along the eroding wadi edge, while maximizing Building 37’s remaining interior space, left the wall exposed and risked continued collapse. The poor preservation of Wall 2, which is much reduced in height compared to the original wall and had also lost its exterior face, suggests the position of the later wall addition was quite precarious and, eventually, continued to tumble down the eroding wadi slope. The overall instability of the western portion of Building 37 is further attested by a series of crack lines and slumping visible within the westernmost portion of the clay floor surface (Fig 3), which was preserved when Building 37 was destroyed by fire and the floor surface baked after the burning roof collapsed.

Some (ca 4m2) later PPNB unexcavated deposits remain outside the south side of Building 37 and may conceal an additional Phase A building although this is unlikely given the small area of unexcavated deposits and absence of walls eroding out of the western, wadi-side edge of these deposits. The combination of open space to the east of Building 37, the wadi edge located immediately to the west of the structure, a lack of a space suitably large enough to accommodate an additional building between 41/56 and 37, and the likely absence a structure immediately south of Building 37, together suggests that Building 37 was set at least slightly apart from contemporaneous Phase A buildings. The relative isolation provided by the space around Building 37 is in marked contrast to the majority of the other Phase A buildings which are closely packed together, regularly share walls with one another, and often incorporate older Phase A walls into newer Phase A structures. The separation of Building 37 from other Phase A buildings appears intentional and designed to mark Building 37 as distinct (Fig 2). Communal buildings located in the northern Levant and dating to the earliest PPNB, for example at Jerf al Ahmar, show a similar isolation from contemporary structures [41].