A Unique Human-Made Trench at Tell eṣ- Ṣâfi/Gath, Israel: Anthropogenic Impact and Landscape Response

Transcription

1 A Unique Human-Made Trench at Tell eṣ- Ṣâfi/Gath, Israel: Anthropogenic Impact and Landscape Response Oren Ackermann, 1, * Hendrik J. Bruins, 2 and Aren M. Maeir 1 1 The Institute of Archaeology, The Martin (Szusz) Department of Land of Israel Studies and Archaeology, Bar Ilan University, Ramat Gan, Israel 2 Ben-Gurion University of the Negev, The Jacob Blaustein Institute for Desert Research, The Department of Man in the Desert, Sede Boker Campus, Israel Tell eṣ- Ṣâfi/Gath is situated in the semiarid foothills of central Israel, adjacent to the coastal plain. An enigmatic landscape feature, noted on aerial photographs, encircles the tell on three sides. This unique feature, unknown from other Near Eastern tells, was investigated. Methods of analysis include aerial photographs, field surveys, excavations, soil analyses, chronotypological ceramic classification, and radiocarbon dating. We concluded that (1) the peculiar landscape feature is a huge human-made trench, over 2 km long, 5 6 m deep, and more than 8 m wide, cut through bedrock; (2) the trench was excavated during the Iron Age IIA (ca B.C.E.), apparently as part of a siege system; (3) the extracted rock and soil material was dumped on the Iron Age landscape surface on one side of the trench, forming an elevated berm ; (4) erosion processes transformed this landscape scar, as the trench filled with sediment; (5) stratigraphic analysis indicates two major phases of filling, separated by a period of landscape stability and soil formation (A horizon); (6) the two filling phases, exhibiting Iron Age IIA and Byzantine pottery (ca C.E.), appear to coincide with more intense human activity; and (7) the possible effect of climatic variations seems less obvious Wiley Periodicals, Inc. INTRODUCTION The Mediterranean landscape has been under human pressure for a long time, at least since the Neolithic period. Grazing, woodcutting, and fires are prominent aspects of human utilization of the landscape (Naveh and Dan, 1973; Naveh and Kutiel, 1990). Such human pressure can reduce vegetation cover and lead to an increase in runoff and erosion (Bell and Walker, 1992). On the other hand, a decrease in human interference may enable a recovery of woody vegetation cover (Pignatti et al., 1995) and a decrease in soil erosion (Thornes, 1990). Naveh and Kutiel (1990) demonstrated that, in historical times, there were cycles of degradation and regeneration related to periods of land-use. They also *Corresponding author. Geoarchaeology: An International Journal, Vol. 20, No. 3, (2005) 2005 Wiley Periodicals, Inc. Published online in Wiley Interscience ( DOI: /gea.20051

2 ACKERMANN, BRUINS, AND MAEIR demonstrated a correlation between wood clearance and population density. During periods of terrace abandonment and neglect, intensive soil erosion occurred, followed by regeneration (Naveh and Dan, 1973). According to these observations, vegetation cover and erosion processes appear to be affected by human activity. Evidence of the sequence of erosion and sedimentation processes is usually found through stratigraphic studies of sediments on slopes and in valleys. Vita- Finzi (1969) suggested there was widespread valley sedimentation in the Mediterranean region during Roman-Medieval times, and referred to it as the historic fill. Concerning the possible effect of climatic variations, Goldberg (1984) and Bruins (1986) saw relationships between aggradation and relatively wet climatic periods in valley sediments in the desert region of northeastern Sinai, at the western edge of the Negev highlands. They concluded that degradation processes correspond to drier periods. Similar palaeoclimatic-landscape evidence was discussed by Rosen (1986, 1995) in a study of the Shephelah (Judean foothills) region of Israel, in the vicinity of Tell Lachish (situated 15 km south of Tell eṣ- Ṣâfi/Gath). However, Rosen (1986) also concluded that, in terms of human impact on erosion, the inclusion of worked stones in colluvial deposits on valley slopes the valleys near archaeological sites seems to be the result of neglect and abandonment of the sites and their surrounding agricultural areas. Wagstaff (1981) emphasized the importance of identifying the origin of the sediment in order to determine whether the erosion was caused by human or natural factors. However, in regard to alluvial fills in valleys, the sediment is often transported through a large basin, making the identification of its specific origin difficult. Filled ditches and trenches, such as those found adjacent to archaeological sites, contain eroded material derived from the surrounding slopes. Investigation of the fill layers in such structures may provide details about slope erosion history (Limbrey, 1975; Bell et al., 1996). Our research focused on a unique human-made trench that surrounds much of Tell eṣ- Ṣâfi/Gath. The investigations were carried out in conjunction with an ongoing excavation project that has been conducted at the site since 1996 (Maeir and Ehrlich, 2001). This article reports the results of geoarchaeological research at Tell eṣ- Ṣâfi/Gath, and presents: 1. Evidence for the anthropogenic origin of the trench. 2. The stratigraphy of the berm adjacent to the trench. 3. The stratigraphy of the fill that accumulated inside the trench. 4. The properties of natural soils in the immediate vicinity of the trench and berm. 5. Archaeological age-assessment of the berm and the fill layers inside the trench, and radiocarbon ages. 6. Evaluation of the fill stratigraphy in the trench vis-à-vis the landscape-response, and its relation to possible human impact and palaeoclimatic effects. 304 VOL. 20, NO. 3

3 ANTHROPOGENIC IMPACT AND LANDSCAPE RESPONSE ENVIRONMENTAL AND ARCHAEOLOGICAL BACKGROUND OF TELL EṢ- ṢÂFI/GATH The tell is situated on the border between the Judean Shephelah (Judean foothills) and the southern coastal plain ( Philistia ; Figures 1 and 2). The foothills and the tell itself are primarily composed of white chalk covered by thick Nari (a local name for a calcareous caliche crust). The Eocene-age chalk belongs to the Maresha Member of the Zor a Formation, which has a marine origin. There are outcrops of the Pliocene-age Pleshet Formation, a calcareous, pebbly sandstone (Buchbinder, 1969). The soils around the tell consist of Brown Rendzinas on the Eocene hills that are covered by Nari, and Pale Rendzinas on chalk that lack Nari. The valleys and the eastern coastal plain have Dark Brown soils and/or Grumusols developed in aeolian or mixed aeolian-alluvial deposits (Dan et al., 1972, 1976; Bruins and Yaalon, 1979). The mixed aeolian alluvial deposits are composed of alluvium eroded from the hills, and clay-rich aeolian loess derived from the deserts located to the south of the site (Yaalon and Dan, 1974; Dan and Bruins, 1981; Bruins and Yaalon, 1992). The study area has a semiarid Mediterranean climate characterized by a hot, dry summer and a cool, rainy winter. The mean annual temperature is 20 C. The rainy season can last from October to May, and the mean annual rainfall is 500 mm (Department of Surveys, 1985; Israel Meteorological Service, personal communication, 2001). The vegetation of the study area is typical of the xeric Mediterranean phytogeographic region. It is dominated by dwarf shrub ( Batha ), including Rhamnus and Sarcopoterium spinosum (Naveh, 1989). Tell eṣ- Ṣâfi/Gath is one of the largest pre-classical archaeological sites in Israel (Figures 3 and 4). Most scholars identify the tell with biblical Gath of the Philistines (e.g., Rainey, 1975; Schniedewind, 1998; Maeir and Ehrlich, 2001), one of the most important Philistine cities during the early period of Philistine history (Iron Age I-II, ca B.C.E.) The tell was inhabited almost continuously from the Chalcolithic period (5th millenium B.C.E.) until modern times. It is a rich source of archaeological data for approximately the last six millennia (Maeir and Ehrlich, 2001). METHODOLOGY The geoarchaeological investigation included the use of aerial photographs; excavations of the trench fill, adjacent berm, and nearby natural soils; soil profile analysis and stratigraphic assessment; laboratory analysis of selected soil samples; chronotypological classification of ceramic sherds found in the berm and trench fill; and radiocarbon dating. Following aerial photography, a field survey was conducted to study the trench in its environmental and archaeological setting. Next, an excavation was carried out at a selected location along a cross-section spanning the width of the trench and the adjacent berm. The northeastern part of the trench was selected, in an area devoid of buildings or terraces, displaying minimal evidence of current grazing activity, and at some GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL 305

4 ACKERMANN, BRUINS, AND MAEIR Figure 1. A map of Israel showing the location of Tell eṣ- Ṣâfi/Gath. 306 VOL. 20, NO. 3

5 ANTHROPOGENIC IMPACT AND LANDSCAPE RESPONSE Figure 2. Map of the Shephelah region of Israel showing the location of Tell eṣ- Ṣâfi/Gath. GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL 307

6 ACKERMANN, BRUINS, AND MAEIR Figure 3. General view of Tell eṣ- Ṣâfi/Gath. distance from the main tell site. Excavation across the trench covered an area of 10 5 m. The excavated sections across the adjacent berm were two squares (nos. 1 and 2) measuring 5 5 m and one square (no. 3) measuring m (Figures 5, 6, and 7). Ceramic sherds were collected as they appeared, enabling a stratigraphic classification of the trench fill in relation to archaeological cultural periods. The trench fill is characterized by a sequence of layers or horizons that are distinguishable by color and structural differences. Samples were collected in stratigraphic order along six profiles: three in the trench and three in the berm adjacent to the trench, at intervals of cm. Laboratory analyses were conducted in the Geomorphology and Soil Laboratory at Bar-Ilan University. Sedimentation analysis (Wright, 1939) was carried out to determine particle-size distribution, and organic matter content was measured by the wet combustion dichromate method (Rowell, 1994). It is well known that organic matter content in the soil usually decreases with depth. Evidence of a buried palaeo-a horizon in the trench fill would indicate a stable period of soil formation and, by implication, would correspond to a period of minimal erosion on the slopes above the trench. Natural soils in the surrounding area were also investigated for comparison with soil properties in the trench fill and adjacent berm. Samples were extracted from 308 VOL. 20, NO. 3

7 ANTHROPOGENIC IMPACT AND LANDSCAPE RESPONSE Figure 4. Topographic map of the excavation areas at Tell eṣ- Ṣâfi/Gath. Areas A and E are located on the main site. Areas C1 C6 are located along the trench. excavated soil pits located at 25 and 50 m downslope from the trench, and 25 m upslope from the berm (Figure 6). Two very small pieces of charcoal were found in the lower part of the trench fill deposits. These samples were submitted to the Centre for Isotope Research at the University of Groningen (The Netherlands) for 14 C accelerated mass spectrometry (AMS). RESULTS Human Origin of the Trench An aerial photograph (Figure 8) shows a dark feature, which encircles the tell on three sides. Initially, there was no clear explanation for the occurrence of this unique phenomenon, since similar features have not been reported from other Near Eastern tells. Field surveys indicated that this dark feature was a trench of extraordinary dimensions. The trench is 8 10 m wide and 2.5 km long, encircling the eastern, southern, and western sides of the tell. It is important to emphasize that the trench cuts through the slopes and valleys of the existing landscape (Figures 8 and 9). GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL 309

8 ACKERMANN, BRUINS, AND MAEIR Figure 5. Aerial photograph of area C6 (view to the south). Preliminary excavations at various points along the trench were first carried out in 1997 and These excavations showed the trench to be at least 3.5 m deep (the bottom had not been reached) and almost completely filled with sediment derived from the adjacent slopes. An initial hypothesis proposed a human origin for the trench (Boas and Maeir, 1998; Maeir and Ehrlich, 2001), and suggested that it was carved out in the landscape around Tell eṣ- Ṣâfi/Gath, to serve as a siege moat part of an ancient siege system (with a similar function as the Roman circumvallation walls, well known from sites such as Masada in Judea and Alesia in Gaul [e.g., Kern, 1998]). A more detailed survey carried out in the 2000 season revealed a slightly elevated berm parallel to the trench. The berm was not noticed in previous surveys, because of the presence of dense shrub. It was first observed on a slope without much vegetation (Figure 9). Subsequently, the berm was also followed under denser shrubbery along the entire length of the trench. The berm occupies a remarkable spatial position in the landscape, as it is always situated on the far side of the trench, which does not face the tell (Figure 9). Excavation of the berm, discussed below in detail, showed that it is composed of dumped soil and rock material that was obviously removed from the trench during its construction. The slopes across the trench can be divided into four parts: (1) natural Nari-chalk surface, (2) berm, (3) trench, and (4) natural Nari-chalk surface (Figure 9). 310 VOL. 20, NO. 3

9 ANTHROPOGENIC IMPACT AND LANDSCAPE RESPONSE Figure 6. Schematic plan of area C6 (plan view and cross-section). Excavation of the Berm The berm was found to be composed of quarried stone flakes and soil, clearly dumped by the ancient people who cut the trench into the landscape. Nari surface GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL 311

10 ACKERMANN, BRUINS, AND MAEIR Figure 7. View of square 2 excavated in the berm. The Nari that was uncovered during excavation is visible in the foreground (a); a section revealing the stratified material that was placed on top of the Nari can be seen at the back of the photo (b); the layer of dense stone quarry flakes is clearly visible (c). bedrock and pockets of original Dark Brown Rendzina soil below the berm were reached at depths ranging from cm (Figures 7 and 8). In squares 1 and 2, sherds from the Middle Bronze, Late Bronze, and Iron Age I periods (ca B.C.E.) were found in the original topsoil. They were covered in at least one spot by an occupation level dating to the Iron Age IIA (ca. the end of the 9th century B.C.E.). This level was found below stone quarry flakes, part of the material that was dumped to form the berm, during the construction of the trench. The quarry flakes are quite diagnostic, and show unambiguously the extent of the human-made deposit above the original soil surface (Figure 7 and Table I). The stratigraphy indicates that the trench was made during or after the Iron Age IIA. Excavation of the Fill Deposits Inside the Trench Excavation at the selected location within the trench demonstrated the great vertical dimension of the trench, as the bottom was reached at a depth of 5.5 m. Analysis of the fill deposits inside the trench revealed the presence of eight distinguishable layers (Figures 10 and 11). The main characteristics of these layers are outlined in Table II. 312 VOL. 20, NO. 3

11 ANTHROPOGENIC IMPACT AND LANDSCAPE RESPONSE Figure 8. Aerial photograph of Tell eṣ- Ṣâfi/Gath. Figure 9. View of the trench, berm, and Nari. GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL 313

12 ACKERMANN, BRUINS, AND MAEIR Table I. Main characteristics of the stratigraphic layers in the berm in square 3. Archaeological Depth Ceramic Age Assessment Layer (cm) Color Texture Finds of the Sherds Notes YR 6/2 Clay loam Iron Age IIA B.C.E /25 10YR 5/3 Clay loam Iron Age IIA B.C.E. Quarry flakes YR 6/2 Clay loam Iron Age IIA B.C.E. Quarry flakes 4 90 Iron Age IIA B.C.E. Dense quarry flakes Near the bedrock at the bottom of the trench, several intact or largely reconstructable Iron Age II vessels were found. These articulated vessels probably fell into the trench not long after the trench was quarried (see below). Table II shows a distinct gap between the sedimentation of Iron Age Layers 4, 5, 6, 7, and 8 and Layer 3. Whereas Layers 4, 5, 6, 7, and 8 contain Iron Age II sherds, the sherds in Layer 3 are from the Byzantine period. This may indicate a gap of at least 800 years between the deposition of Layer 4 and Layer 3. The color of Layer 3 is significantly lighter than the other layers. In contrast, Layer 4 is particularly dark, exhibiting buried A horizon properties. Quarrying/stonecutting marks are visible on the bedrock, while quarry flakes are evident in the fill material in Layers 7 and 6. The rock flakes were first carved from the bedrock, then removed from the trench and dumped onto the berm. Later, these quarried rock flakes slid back into the trench, as slope processes and gravity caused erosion of the berm and fill accumulation inside the trench. Table II and Figures 10 and 11 show that the bottom of the trench was filled by pebble- to cobble-sized stones. Coarse bedrock material, the last stage of trench excavation, seems to have been the first material to fall back into the trench. Upper layers of the fill are characterized by finer material. Radiocarbon Dating The excavation of the fill deposits inside the trench revealed two tiny spots with very small pieces of charcoal. The two samples are derived from different sections of Layer 6 in the northern and northeastern part of Locus 40019, at depths of 3.55 and 4.04 m, respectively. The charcoal became incorporated in the fill deposits, either in situ or through slope erosion and redeposition. The stratigraphic details and radiocarbon ages are presented in Table III. The radiocarbon ages of both samples are nearly identical: years yr B.P. (GrA-17241) and years yr B.P. (GrA-15355). The 14 C dates have a standard deviation of 40 and 60 years, respectively, but the calibrated dates have a very wide age range of several hundred years. This is due to the so-called Hallstatt plateau in the calibration curve, caused by one of the most pronounced short-lived increases in atmospheric 14 C content between calendar years 850 and 760 B.C.E. (Van Geel and Renssen, 1998). As a result, there are about 300 radiocarbon years in less than 100 calendar years during this time interval. Radiocarbon years during that period 314 VOL. 20, NO. 3

13 ANTHROPOGENIC IMPACT AND LANDSCAPE RESPONSE Figure 10. View of the section exposed in the excavated trench. The fill layers are visible in the background. Dense stone fragments and quarry flakes can be seen at the bottom of the section. A large boulder located near the middle of the section marks the transition from Layer 4 to Layer 3. Sherds dating from the Iron Age II were found below the boulder; sherds from the Byzantine period were found above. GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL 315

14 ACKERMANN, BRUINS, AND MAEIR Figure 11. Cross-section of the trench showing fill layers and organic matter content. (ca yr B.P.) were of a very short duration. Consequently, the 14 C age remained at about 2750 yr B.P. during the following 300 calendar years, from ca cal B.C.E. The 1 calibrated date of GrA ( yr B.P.) gives four possible age ranges: B.C.E. (27.0%), B.C.E. (9.4%), B.C.E. (21.6%), and B.C.E. (10.2%). The first subrange, covering the first half of the 8th century B.C.E., has the highest relative probability (27.0%) of the four options. This period also seems to correlate best with the Iron Age IIA sherds found in Layer 6. The other charcoal sample, GrA-15355, is somewhat younger. As with the other sample, the highest relative probability (22.4%) of the four calibration options, cal B.C.E., is with the Iron Age. Natural Soils in the Vicinity of the Trench and Berm The natural soil was examined in three pits that were dug in the vicinity of the trench and berm. The natural soil is a Brown Rendzina, with a dark brown Munsell (1998) color 316 VOL. 20, NO. 3

15 ANTHROPOGENIC IMPACT AND LANDSCAPE RESPONSE Table II. Main characteristics of the stratigraphic layers in the trench fill deposits. Archaeological Depth Ceramic Age Assessment Layer (cm) Color Texture Finds of the Sherds Notes YR 6/2 Clay loam Ottoman Topsoil YR 6/2 Clay loam Byzantine C.E. Dark layer YR 7/2 Clay loam Byzantine C.E. This layer has a remarkably light color; one large pebble, 50 cm in diameter, imbedded YR 6/3 Silty clay Iron Age II A B.C.E. Dark layer: buried A- horizon; one cobble, 75 cm in diameter, embedded YR 7/2 Silty clay loam Iron Age II A B.C.E YR 7/2 Silty clay Iron Age II A B.C.E. Part of this layer contains many stones; charcoal samples are derived from silty clay matrix; few boulders Stony Iron Age II A B.C.E. Compact quarrying flakes YR 5/3 Clay Iron Age II A B.C.E. Thin soil layer Table III. Radiocarbon dating ages and stratigraphic information. Layer Calibrated Sample and Ceramic Lab 14 C Date Date* cal No. Depth Comment Area Locus Culture No. yr B.P. B.C.E. Basket Layer 6 Charcoal Area C-6, Iron GrA : (27.0%) m pieces in Square A Age II ( 9.4%) trench fill (21.6%) (10.2%) 2 : (95.4%) Basket Layer 6 Charcoal Area C-6, Iron GrA : (22.4%) m pieces in Square A Age II ( 8.8%) trench fill ( 3.5%) (21.0%) (12.5%) 2 : (95.4%) * Based on the 1998 calibration curve (Stuiver et al., 1998) and the OxCal program (Bronk Ramsey, 1995). GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL 317

16 ACKERMANN, BRUINS, AND MAEIR (7.5 YR 3/2). The soil lies above the hard Nari and is generally very shallow, with an average depth of 15 cm. There are pockets in which the soil extends to a depth of 50 cm. The A horizon has a granular or crumb structure, a clay-loam texture, and contains gravel fragments up to 5 cm in diameter. In shallow soils, the A horizon lies directly on the Nari crust. In deeper soils, the A horizon is underlain by a stony C1 horizon, containing 35-50% rock fragments that are up to 25 cm in diameter. Under the C1 horizon lies a clayey C2 horizon. The transition from C2 to the underlying Nari bedrock is rather sharp. Laboratory Analyses of the Trench Fill, Berm, and Nearby Soils Organic Matter Content The organic matter content of the trench fill generally decreases with depth in the three profiles that were investigated (Table IV). The organic matter content in the topsoil ranges from 4.50% to 5.93%. The deepest fill layers in the trench have an organic matter content of only %. However, the steady decline in organic matter content shows a reversal in some horizons. This is most significant in Layer 4, in which the organic matter content shows a relative increase of approximately 20%, from about 0.60% to 0.80% (Figure 11). The organic matter content in the berm generally decreases with depth in the three profiles that were investigated. In the topsoil, it ranges from 3.20% to 6.72%. In Layer 2, it ranges from 1.94% to 2.48%. In Layer 3, it ranges from 0.62% to 0.67%. Two profiles show an increase in the deepest layers closest to the bedrock. In Berm Profile 1, the organic matter content increases from 0.67% to 1.02% between 47.5 cm and 90 cm; in Berm Profile 3, it increases from 0.62% to 0.74% between 77.5 cm and 95.0 cm. This increase in organic matter seems to indicate the level of the original topsoil, prior to deposition of the berm material by humans. The three pits that were dug into the natural soils nearby show a general decrease in organic matter with depth, from 4.72% to 6.46%. In Pit 2, it declines from 5.20% to 4.5%; in Pit 3, it declines from 6.46% to 2.29%. However, Pit 1 initially shows a decline in organic matter, from 4.72% to 1.69% at a depth of 35 cm, and then shows an increase to 2.27% at a depth of 45 cm, close to the bedrock. Particle-Size Analysis The particle-size distribution of the various layers in the trench fill, the berm, and the natural soil pits, are summarized in Table V. In the trench, Layers 1, 2, and 3 contain somewhat more sand and less clay, relative to the deeper layers. The texture of these upper layers is predominantly clay loam. The clay content fluctuates in the range from 30% to 34%. The fine silt content is comparatively low (20.6%) in the uppermost layer, Layer 1, and remains low in Layer 2 (about 25 26%). The important transition in the trench, from Layer 3 to the darker Layer 4, is accompanied by an increase in clay content from 32.8% to 36.6%, and a texture change from clay loam to silty clay. The highest clay and lowest fine silt content is found just above the bottom of the trench in Layer 8, being 47.2% and 16.1%, respectively. 318 VOL. 20, NO. 3

17 ANTHROPOGENIC IMPACT AND LANDSCAPE RESPONSE Table IV. Organic matter content of the trench fill, berm, and natural soils. Profile 1 Profile 2 Profile 3 Depth (cm) Organic Depth Organic Depth Organic Layer of sample Matter (%) (cm) Matter (%) (cm) Matter (%) Trench Quarry flakes Quarry flakes Quarry flakes Quarry flakes Quarry flakes Quarry flakes Berm Bedrock Natural Soils Bedrock The results from the berm show that all the layers have a clay loam texture. The clay content is 31 36%, and the fine silt content is 18 24%. The fill deposits in the trench show a significantly higher fine silt content in Layers 3 6, ranging from 28% to 32%, as compared to the berm. The natural soils show an even lower fine silt content of only 6 18%. These differences are most interesting and need to be evaluated in terms of slope erosion, GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL 319

18 ACKERMANN, BRUINS, AND MAEIR Table V. Particle-size distribution* of the trench fill, berm, and natural soils. Coarse Fine Layer Depth Sand Silt Silt Clay Total Texture Trench Clay loam Clay loam Clay loam Clay loam Clay loam Silty clay loam Clay loam Silty clay Silty clay Silty clay loam Silty clay loam Silty clay loam Silty clay loam Silty clay Silty clay loam Quarry flakes Clay Berm Clay loam Clay loam Clay loam Clay loam Clay loam Natural Soil Pit Clay loam Clay loam Silty clay loam Silty clay Clay Natural Soil Pit Clay loam Clay loam Natural Soil Pit Clay loam Clay loam Clay Silty clay Clay * The size limit dividing sand and coarse silt is mm. 320 VOL. 20, NO. 3

19 ANTHROPOGENIC IMPACT AND LANDSCAPE RESPONSE fill deposition, weathering, pedogenesis, and dust accretion. The highest clay content in the natural soils, 47.5% (Pit 1) and 48.9% (Pit 3), occurs in the deepest layer/horizon, just above the Nari bedrock. Finally, the highest sand content is consistently found in the surface layers/horizons of the trench (29.8%), berm (29.9%), and natural soils (28.5% Pit 1; 32.8% Pit 3). The only exception is the shallow soil in Pit 2, which is only 15 cm deep. DISCUSSION AND CONCLUSIONS The trench is clearly of human origin. This conclusion is securely based on: (1) the geomorphic position of the trench on the landscape and its spatial position visà-vis the tell; (2) the presence of abundant quarrying rock flakes dumped onto the berm adjacent to the trench; (3) the remnants of the berm covering earlier cultural remains; (4) tool marks on the chalk bedrock inside the trench; (5) the presence of complete Iron Age II vessels at the bottom of the trench below the fill deposits; and (6) the presence of Iron Age II sherds in the lower fill layers. The berm, located along the entire length of the trench, is composed of dumped soil and rock material that was removed during the excavation of the trench. It is quite significant that the material was dumped on only one side of the trench; the side that does not face the tell, in most cases uphill from the trench. The dumped material that formed the berm buried a section of the natural landscape surface along the entire length of the trench. Imbedded ceramic sherds indicate that the construction of both the trench and the berm date to the Iron Age II. This conclusion can be substantiated by the following evidence: 1. The dumped material (berm) covers archaeological cultural deposits on the former landscape surface that date to no later than the Iron Age IIA (ca. late 9th century B.C.E.). Thus, the earliest date for the deposition of the berm is Iron Age IIA. 2. In the lower layers of the trench fill, several intact (or largely restorable) vessels dating to the Iron Age IIA were found. It is assumed that these vessels fell into the trench during the filling process. Since the vessels were intact (or relatively articulated), they could not have fallen into the trench very long after the time of their original use. Otherwise, they would have shattered, and the pieces would have dispersed over a wider area prior to having fallen into the trench. Thus, the initial phases of the filling of the trench could not have occurred much later than the Iron Age IIA. From these two reasons, we have both a terminus post quem and terminus ante quem for the original excavation and initial filling of the trench, both within a limited time frame, during, or not long after, the Iron Age IIA. Following its excavation and use, the human-made trench gradually filled with sediments. Soil and rock fragments moved down from the berm and the surrounding landscape due to natural processes. However, part of the excavated material stabilized in the berm and has not eroded back into the trench until today. An excavated section of the berm reveals Iron Age sherds and quarry flakes of chalk lying directly on Nari rock outcrops. Therefore, the former Iron Age surface GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL 321

20 ACKERMANN, BRUINS, AND MAEIR prior to the construction of trench and berm is quite similar to the current surface area of the slopes. The principal overall slope appearance of Nari rock outcrops and soil pockets has not changed in the last 3000 years. Research conducted in the Mediterranean region of southeastern Spain (Thornes and Gilman, 1983; Gilman and Thornes, 1985) showed that highly eroded slopes close to archeological sites underwent only limited soil erosion since the Bronze Age. Studies of trenches constructed in nonstable material have shown that fill deposits can include material from collapsed trench walls (Limbrey, 1975; Bell et al., 1996). However, the trench around Tell eṣ- Ṣâfi/Gath was generally dug in solid rock, i.e., chalk with a very hard upper calcrete crust (Nari). We did not find any evidence of collapsed walls. Ancient quarry signs on the trench walls became clearly visible as we removed the fill during excavation. It shows that the original trench walls have remained stable. The fill material in the trench seems to be derived primarily from the berm and the surrounding landscape with a continuous, but relatively small influx of aeolian dust (Bruins and Yaalon, 1979, 1992). Eight fill layers were identified in the trench. Larger rock fragments dominate in the lower layers, and fine soil material prevails in the upper layers. Experimental studies of ditches and trenches in Britain have demonstrated that large fragments usually fall in before fine material slides down (Limbrey, 1975; Bell et al., 1996; Evans and O Connor, 1999). Sometimes a mixture of coarse and fine fill material may be deposited together because of human activities such as cultivation or grazing (Bell et al., 1996). An evaluation of the fill layers shows that Layer 8, which represents the first stage of the filling process, is a thin layer (5 10 cm deep) containing clay and fine material, similar to the deepest natural Brown Rendzina soil horizon that overlies the Nari bedrock. Although this layer contains fine material, it is considered primary fill. A possible explanation for the combination of material is that the loose upper part of surface area soil moved down during the quarrying of the trench. Some of this soil would have been removed during quarrying and some would have remained in the trench. Alternatively, the fine soil material of this layer may be aeolian in nature or it may have been washed into the trench during the first rainy seasons after its construction (Limbrey, 1975). Layer 7 is characterized by large, pebble- to cobble-size rock fragments. It is a fill comprised of quarry fragments that probably fell in from the adjacent berm. It seems that coarse chalk and Nari rock material, the last material excavated from the deepest part of the trench and dumped on top of the berm, was the first to slide back into the trench. Layer 6 contains both large, pebble- to cobble-size rock fragments and fine soil material. Large fragments prevail in the western part of the layer and fine soil material dominates in the eastern part of the layer. This might indicate that more intense human interference occurred during the deposition of this layer, such as deliberate filling of the trench. Only Layer 6 exhibits this combination of fill types, suggesting that if intense human activity was its cause, the activity ceased or significantly decreased, after this layer was deposited. Another possible explanation for the composition of Layer 6 could be that the surface area to the west of the trench contained a greater quantity of coarsegrained material than the surface area in the east during the period of sedimentation. 322 VOL. 20, NO. 3

21 ANTHROPOGENIC IMPACT AND LANDSCAPE RESPONSE Clearly, Layer 6 is an intermediate layer between the coarse fill found in Layer 7 and the fine fill found between Layer 5 and the present surface. In addition to the Iron Age II sherds, two tiny charcoal samples were extracted from Layer 6 for AMS radiocarbon dating. The small size of these samples may suggest that they were derived from local shrubs. The somewhat older date of yr B.P. (GrA-17241) is situated some 50 cm above the younger date of yr B.P. (GrA-15355). This may point to variability in slope erosion and filling processes, by which older trench material may be deposited above younger material. However, as the samples are not from exactly the same profile, the fill surface may have been wavy (not horizontal), so that the depth at different spots may not correspond exactly to the same stratigraphic (age) layer. Regardless, the calibrated dates of both samples largely overlap, and both are affected by the Hallstatt plateau in the calibration curve. The wide calibrated age ranges of both samples allow them to be associated with Iron Age events from 800 to 585 B.C.E., the end of the Iron Age. Despite this rather wide age range, more precise dates can be argued based on the cultural remains and historical evidence. The ceramic sherds from Layer 6 and below can be dated to the Iron Age IIA (ca. late 9th century B.C.E.) and not later. In addition, there were no remains in or around the trench that could be dated to later phases of the Iron Age, and/or to periods immediately after the Iron Age (Persian and Hellenistic). On the nearby tell, the late 9th century B.C.E. is represented by a large and substantial settlement that was destroyed in a large, encompassing fire. Subsequently, the tell was not intensively settled for several centuries. Historically, there is no evidence for intense military activity at this site in the Iron Age after the early 8th century B.C.E. In fact, a most likely scenario for the construction of the trench and the related siege would be the capture of Gath by Hazael, king of Aram Damascus, at the very end of the 9th century B.C.E., as mentioned in II Kings 12:17 (Dion, 1997; Lipiński, 2000). In the next stage of the filling process, finer material was eroded from the berm and slope, forming Layers 5 and 4. Apparently, there was a pause in the filling process after the gradual sedimentation of Layer 4. This can be deduced from the pottery sherds embedded in the fill layers, as Layer 4 contains pottery dating to the Iron Age IIA ( B.C.E.), while Layer 3 contains Byzantine period sherds ( C.E.). This may indicate a depositional hiatus of approximately 1 millennium. Moreover, it is important to emphasize that the organic matter content increases in Layer 4. This seems to indicate the presence of a buried A horizon, formed during a relatively long period of landscape stability, when the geomorphic surface of the trench fill remained at about m below the present surface. Such soil formation is a sign of stable conditions (Rapp and Hill, 1998; Limbrey, 1975). During or after Byzantine times, this stable period ended, slope erosion increased, and sediment composing Layer 3 was deposited in the trench. Layer 3 has a lighter color (light gray 10YR 7/2 [Munsell, 1998]) than the layers below and above it. This may indicate a period of more rapid sedimentation with a lower rate of soil and humus formation, resulting in a lighter color. Rapid sedimentation may have been due to decreased surface vegetation cover that may have resulted from drier climatic conditions or an increase in the intensity of human activities such as grazing. The Byzantine pottery sherds in Layers 3 and 2 allow correlation with the historic fill in the GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL 323

22 ACKERMANN, BRUINS, AND MAEIR Mediterranean valleys (Vita-Finzi, 1969), although the trench is obviously a very unusual valley. Bruins (1986) also found clear evidence for extraordinary valley aggradation in northeastern Sinai during the period between 1200 and 1700 C.E. Aggradation may have started in Roman-Byzantine times, but a period of incision in the Early Islamic period seems to divide the historic fill into two separate parts (Bruins, 1986). The eight layers identified in the trench fill seem to represent eight fill phases. The transition from one layer to the next may attest to a change in the conditions of the surrounding environment, either as a result of climatic variation and/or human influence. With respect to climatic history, Bell and Walker (1992) show that erosion increases during periods of high rain intensity. In our case, fill processes in the trench might have been pronounced at the beginning of the rainy season, when rain intensity can be high and vegetation cover is low after the dry summer period that lasts for about 5 months. Moreover, following the construction of the trench, there was probably no protective vegetation cover on the berm during the first years, when fill processes may have been strongest. Two palaeoclimatic reconstruction records were used in this research. The first record (Bar Matthews et al., 1998; Schilman et al., 2002) is based on speleothems in the Soreq Cave (located 18 km east of our research site) and planktonic foraminifera Globigerinoides rubber marine deposits off the Ashdod Coast (approximately 23 km northwest of our research site). The second record is based on Dead Sea water level history (Frumkin, 1997). Study of both records indicates that the period B.C.E. was characterized by relatively drier conditions. Most of the fill (Layers 4, 5, 6, 7, 8) accumulated during the beginning of this period, as indicated by Iron Age IIA pottery sherds and two radiocarbon dates. During the next period, from 500 B.C.E. to 300 C.E., both palaeoclimatic records show that the conditions turned from drier to wetter. In the trench, this period is characterized by stable conditions, evident in the presence of a palaeo-a horizon. Deposition of the palest layer (Layer 3) occurred during the Byzantine period (ca C.E.). According to Frumkin s (1997) record, this period was relatively wetter, changing around 400 C.E. to relatively drier. According to Schilman et al. s (2002) record, the period was relatively wetter until 700 C.E. Both records show that wetter conditions began prior to the Byzantine period. In conclusion, there does not seem to be a clear relationship between climate history and the fill accumulation history of the trench. On the other hand, there seems to be a distinct chronological relationship between human activity and fill deposition. The quantity of pottery sherds in a certain fill layer may be related to the level of human activity near the trench during or just after the cultural period represented by the sherds. On the basis of this premise, there was significant human activity during the Iron Age II, as indicated by the large amount of pottery from this period. The erosion/filling rate was comparatively high, as the lower 3.9 m out of the total 5.5 m of fill deposits contained Iron Age II sherds. Persian, Hellenistic, or clearly datable Roman pottery (as opposed to sherds that date roughly to the Roman-Byzantine period) were not found in the fill layers. Moreover, low human activity from the end of the Iron Age until the Byzantine period 324 VOL. 20, NO. 3

23 ANTHROPOGENIC IMPACT AND LANDSCAPE RESPONSE seems to correlate with a low erosion/filling rate. The pottery from the Byzantine period, which was less abundant than the Iron Age pottery from the earlier layers, reflects activities during and/or immediately after this period in the vicinity of the trench. The fact that Layers 3 and 2 contain no sherds from the Early Islamic or other Medieval periods seems to indicate that this filling phase did not occur much later than the Byzantine period. In addition to possible climatic influences, renewed fill deposition during and/or immediately after the Byzantine period may also be correlated with intense human activity. Byzantine period pottery sherds characterize the upper layers almost up to the present surface. Only the uppermost 10 cm of fill deposits contain Ottoman period pottery sherds. It might be concluded that berm slope erosion and trench deposition more or less ceased at some time after the Byzantine period. At this time, the trench was almost completely filled. Fluctuations in the level of human activity during these periods are not only seen in pottery inclusions in the trench fill, but also seen in the archaeological evidence at Tell eṣ- Ṣâfi/Gath (Boas and Maeir, 1998; Maeir and Ehrlich, 2001), and the archaeological survey of the site and the adjacent region (Dagan, 1992, 2002). According to these studies, human population in the region increased during the Iron Age and the Byzantine period. Such increases probably resulted in more intensive human activities that exacerbated the conditions necessary for soil erosion. While the effects of human activity on vegetation cover in ancient times cannot be measured directly, a study of human impact in modern times may enable historical-environmental reconstruction. In subhumid Mediterranean areas susceptible to slope erosion (Morgan, 1995), vegetation cover is a major influence on slope erosion processes (Kirkby et al., 1996). Human activities cause clearance of vegetation and an increase in soil erosion. In our study area, there is no evidence of agricultural terraces. The land is nonarable, contains Nari outcrops and small soil pockets, and seems most conducive to human activities such as grazing and wood-cutting. A reduction in human activity allows for revegetation, a process that requires at least a few decades (Svoray et al., 2003). Revegation leads to a reduction in slope erosion processes and increased slope stability (Thornes, 1990; Perevolotsky and Pollak, 2001). Therefore, the stable conditions that existed after the fill deposition of sediment composing Layer 4 were apparently the result of revegetation caused by a reduction in human activity. The authors wish to acknowledge the financial support of the Dr. Simon Krauthammer Chair in Archaeology, the Irving and Cherna Moskowitz Chair for the Study of the Historic Land of Israel, the Koschitzky Family Foundation, and the Joe Alon Center Rimon Association. The authors also thank Professor Hanoch Lavee, Dr. Sarah Pariente, Dr. Helena Zhevelev, and Dr. Natan Fragin, from the Laboratory of Geomorphology and Soil of the Department of Geography at Bar Ilan University, for their advice and assistance in the field and in the laboratory. We are grateful to Professor Hans van der Plicht (Head, Radiocarbon Lab, AMS and PGG facilities) of the Centre for Isotope Research (Groningen University, The Netherlands) for the radiocarbon dating. Finally, we thank Dr. Arlene Rosen and an anonymous referee for their constructive comments. Needless to say, the authors take responsibility for any errors in the text. This article is a portion of the forthcoming Ph.D. thesis of the first author, Oren Ackermann. The research was carried out at the Institute of Archaeology, The Martin (Szusz) Department of Land of Israel Studies, Bar Ilan University, within the framework of the Tell eṣ- Ṣâfi/Gath Archaeological Project, which is directed by the Aren M. Maeir. GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL 325

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