Holocene landscape reconstruction in the surroundings of the Temple of Pepi I at ancient Bubastis, southeastern Nile Delta (Egypt)

In ancient Egypt, lakes, canals, and other water bodies were an essential part of the sacred landscape in which temples were embedded. In recent years, geoarchaeological research at the site of the Temple of Bastet at Bubastis in the southeastern Nile Delta has proven the existence of two water canals surrounding the temple. It has now been investigated whether these canals were connected to the Temple of Pepi I (2300–2250 B.C.E.), located approximately 100 m to the west of the Temple of Bastet. To explore the Holocene landscape genesis of the Temple of Pepi I, 15 drillings and six geoelectrical profile lines were performed in the surroundings of the temple in spring 2022. The results show loamy to clayey sediments in deeper sections of all drillings with a maximum thickness of 1.70 m, indicating a marshy or swampy depositional environment. Based on the recovered sediment sequences and archaeological remains in the vicinity of the Temple of Pepi I, the marshy or swampy area existed before the Fourth Dynasty. During the Old Kingdom (ca. 2850–2180 B.C.E.), the former marshland either dried up through natural processes or was intentionally drained and filled with sediments for subsequent use for occupation. Regarding the original research question, there is as yet no evidence for a direct connection to the canals of the Temple of Bastet.


| INTRODUCTION
The development of ancient Egyptian cities was usually associated with the presence of a differentiated infrastructure, including temples of the local main deities as one of the most important elements (Bußmann, 2010).Besides their religious and cultic importance, local temples developed into institutions of great economic and administrative significance from the time of the Fifth Dynasty (from around 2500 B.C.E.).The temple areas (i.e., temenos) were shielded from the rest of the settlement by an enclosure wall, which encompassed not only the main sanctuary but also minor temples of related cults, buildings for the temple staff, archives, offices, storage areas, magazines, and other administrative and food processing installations (Wilkinson, 2000;Wilson, 2010).
An important element connected to temples were the so-called sacred lakes or canals.In specific cases, that is, when they surrounded the building in the shape of a bend lake or as canals, ancient Egyptian texts refer to them as Isheru.These Isheru were mainly related to temples of goddesses who could appear in the form of lionesses (e.g., Sakhmet, Mut, Wadjet, and Bastet) and who were considered unpredictable and fierce.The presence of a cooling water body near their temples was intended to calm their fiery temperaments and protect the inhabitants of the towns from their possible rage.Besides their pleasing effect on the temper of the goddesses, the Isheru provided water for purification rites and activities.They were also the place where the ceremony of rowing the sacred barque with the statue of the deity took place during religious temple festivals (Gessler-Löhr, 1983;Lange-Athinodorou, 2021;Richter, 2010;Tillier, 2010).While the existence of such canals has been archaeologically proven in the Nile Valley at Thebes, Luxor, and Memphis (Atya et al., 2012;Richter, 2010;Trampier, 2005), for a long time, knowledge of sacred waters in the Nile Delta was based mainly on religious texts.These indicate the existence of sacred water landscapes at Buto (Gessler- Löhr, 1983) and Sais (Gessler- Löhr, 1983;Wilson, 2006Wilson, , 2019) ) in the western Nile Delta, at Busiris (Gessler- Löhr, 1983) in the central Nile Delta and at Tanis (Leclère, 2008;Montet, 1966), and Bubastis (Lange-Athinodorou et al., 2019) in the eastern Nile Delta (Figure 1a).To date, however, a truly comprehensive and more exact reconstruction of a sacred landscape in the Nile Delta has only been achieved for the archaeological site of Bubastis, using sedimentological and geophysical methods in the surroundings of the Temple of Bastet, where two sacred canals have been identified (Meister, Garbe, et al., 2021).
To detect possible connections to the canals of the Temple of Bastet and to investigate the Holocene landscape evolution of the area on a wider scope, the geoarchaeological investigations were recently expanded into the surroundings of the Temple of Pepi I.In March 2022, we conducted two-dimensional (2D) electrical tomography resistivity (ERT) and geomorphological analyses in the relevant area (Figure 1c).Like in our previous investigations, we combined ERT measurements with drillings, an approach that has been used in multiple studies (e.g., El-Kenawy et al., 2013;Kasprzak & Traczyk, 2014;Maillet et al., 2005;Rowland & Strutt, 2012;Torrese et al., 2013).ERT and drillings can detect different sedimentological layers in the subsurface, for example, to identify and locate buried channels, as has been demonstrated in several studies in the Nile Delta and Nile Valley (e.g., Altmeyer et al., 2021;El-Gamili et al., 1994, 2001;Toonen et al., 2018;Wilson & Ghazala, 2021).

| Nile Delta evolution and settlement activities
The Nile Delta is an alluvial plain created by a long series of deltaforming processes since the Paleocene, controlled by natural factors such as climate, sea-level fluctuations, and tectonics (Butzer, 1976;Pennington et al., 2017;Said, 2012;Shata & El Fayoumy, 1970).
During the Quaternary, the alluvial deposits of the Mit Ghamr Formation (pre-Nile sediments) and the Bilqas Formation (neo-Nile sediments) shaped the surface morphology of the Nile Delta.The Mit Ghamr Formation consists mainly of medium to coarse quartzose sands but may also contain gravel layers and finer sediments that were eroded or translocated by ancient Nile branches up to about 6000 cal.B.C.E.Local mounds of these fluvial sands, often redeposited by aeolian processes, form the Geziracover Formation, widely known as Geziras or "turtlebacks" (Pennington, 2017;Pennington et al., 2017).
Between 6000 and 4000 cal.B.C.E., the humid conditions of the mid-Holocene African Humid Period led to increased Nile runoffs and, in combination with an enhanced sediment supply and high rates of sea-level rise, to higher accumulation rates in the Nile Delta region.
There, characterized by a widely interconnected network of small rivers and large flood plains (the so-called "Large-Scale Crevassing" delta), extensive swamps and marshlands developed, forming the bluish-black, silty-clayey to clayey-silty and organic-rich deposits of the Bilqas-2 Formation.Between 4000 and 3500 cal.B.C.E., due to increasingly arid conditions and the decline in sea-level rise, accumulation rates decreased, causing the fluvial landscape of the delta to change significantly.From this time on, well-drained flood plains with individual, large meandering river courses dominated the so-called "Meandering" delta.The brownish-grayish sediments of the Bilqas-1 Formation belonging to this phase covered most of the delta around 2500 cal.B.C.E.(Goodfriend & Stanley, 1999;Pennington et al., 2017Pennington et al., , 2020;;Stanley & Warne, 1993, 1998).River relocations and sedimentation processes have had an ongoing impact on the delta landscape.For the historical period, for instance, there is textual evidence of up to seven large Nile branches.At that time, the Canopic and Saitic branches flowed through the western delta, the Tanitic and Pelusiac branches through the eastern delta, and the Sebennitic and Mendesian branches through the central delta (Bietak, 1975;Butzer, 2002).Nowadays, only the Rosetta and Damietta branches remain.
The Holocene Nile Delta evolution, especially the change from a "Large-Scale Crevassing" to a "Meandering" delta, had a considerable impact on ancient settlement activity and potentials.The younger meandering river system created well-drained alluvial plains, suitable for pasture and agriculture, while the presence of large river courses favored the nearby development of early urban centers, as the river courses were used for regional and supraregional transport and communication (Pennington et al., 2017(Pennington et al., , 2020)).To protect the settlements from the annual Nile floods, they were usually built close to the river on Geziras or high riverbanks, with important structures such as temples and cemeteries set on the highest spot (Butzer, 2002;Garbe et al., 2023;Meister, Garbe, et al., 2021;Said, 2012Said, , 2013;;Van den Brink et al., 1987;Wunderlich & Andres, 1991).
The continuous transformation of the river landscape led to disruptive events in the settlement history of most cities in the Nile Delta, as they were abandoned when the nearby river course changed (Bietak, 1975;Butzer, 2002).One significant exception is the ancient city of Bubastis in the southeastern Nile Delta, which was continuously settled for over four millennia (Lange-Athinodorou, 2019a).

| The ancient city of Bubastis (Tell Basta)
The excavation site of the ancient Egyptian city of Bubastis (Tell Basta) is located in the southeastern Nile Delta, on the southeastern border of Zagazig, about 80 km northeast of Cairo (Figure 1).The ancient city of Bubastis was connected to the Pelusiac and possibly also to the Tanitic branch of the ancient river Nile, but the accurate courses have not yet been precisely pinpointed (Bietak, 1975;El Mahmoudi & Gabr, 2009;Ullmann et al., 2020) (Figure 1b).The proximity to the Wadi Tumilat, the traditional overland route to Sinai and Palestine, afforded the ancient city a beneficial geographic situation to operate as an important transregional trade center for the Levant and the southern Nile Valley.These advantageous circumstances not only led to the original founding of Bubastis, probably during the Predynastic Period (ca.3200 B.C.E.), but also ensured that the ancient city was able to maintain its importance on a constant level, before it gradually declined during the time of the Roman Dominion (ca.200 C.E.) (Meister, Garbe, et al., 2021).
A further important factor for the city's longevity was the significance of Bubastis as the major religious center of the local feline deity Bastet, whose temple increased its importance, especially at the beginning of the Sixth Dynasty (around 2300 B.C.E.) (Lange, 2006).Additionally, Bubastis was of great administrative importance, housing high-level provincial officials (Bakr & Lange, 2016), as suggested by discoveries of a mid-Fourth to Fifth Dynasty provincial palace to the west of the Temple of Bastet (Lange-Athinodorou & Es-Senussi, 2021).The importance of Bubastis as a regional center of provincial government during the Middle Kingdom is further evidenced by the large 12th Dynasty governor's palace and related cemetery (1830 B.C.E.) on the Kom (local elevation with remains of human occupation) in the northern part of the city (Bietak & Lange, 2014;Lange, 2015;Lange et al., 2016) (Figure 1c).
Bubastis reached the peak of its significance as the secondary residence of the Libyan kings during the 22nd Dynasty (ca.900-800 B.C.E.), leading to the modification and enlargement of the Temple of Bastet (Lange, 2008(Lange, , 2009;;Lange-Athinodorou, 2019a, 2019b), which is situated on the central elevation of a Gezira mound (the "Central Kom") (Kitchen, 1996;Lange-Athinodorou, 2019b;Naville, 1891).Several textual sources of the Late Dynastic and Ptolemaic Period refer to the existence of two sacred canals surrounding the Temple of Bastet, as was recently confirmed by geoarchaeological investigations (Lange-Athinodorou et al., 2019;Meister, Garbe, et al., 2021) While the landscape to the north and south of the Temple of Bastet has now been relatively well studied, there is no information about the former hydrogeographical situation in the area to its west, where the Temple of Pepi I is located.

| MATERIALS AND METHODS
To reconstruct the Holocene landscape history in the vicinity of the Temple of Pepi I, geophysical and geomorphological surveys were conducted in March 2022.To achieve this, on-site drilling and 2D geoelectrical measurements were performed in the southwest, northeast, and east of the temple area (Figure 2).The area northwest of the temple is inaccessible for geoscientific survey.Since sample transport is restricted, the extracted sediments were macroscopically described and analyzed on-site.Following the KA5 (Ad-hoc-Arbeitsgruppe Boden, 2005), FAO (WRB-FAO, 2015), and

| Drillings and sediment analyses
Munsell color system (Munsell, 1907), the grain sizes, sediment color, texture, presence of redoximorphic features, and specific characteristics (ceramic and limestone fragments, plant remains, charcoal, etc.) of the sediments were documented.No additional laboratory analyses were carried out.To establish a chronostratigraphy, wellpreserved ceramic fragments embedded in the sediment cores were used, following a methodology similar to that used in other sites in Egypt (Toonen et al., 2018(Toonen et al., , 2022)).The ceramics were compared with well-dated collections from excavations in the Nile Delta (e.g., Ballet et al., 2018;Schiestl & Seiler, 2012) based on fabric, fabrication techniques, shape, and surface treatment and subsequently classified into the time periods of the Kingdoms.

| Electrical resistivity tomography (ERT)
To obtain areal information on the near-surface underground in the surroundings of the Temple of Pepi I, the boreholes were supplemented by ERT measurements.A total of six profiles (ERT 1-6) were measured, usually corresponding to the drilling transects (Figure 2).The 2D ERT data were acquired using an IRIS Syscal R2 instrument.The Wenner-Beta configuration, which is characterized by a high signal-to-noise ratio (Dahlin & Zhou, 2004) and is commonly applied in geoarchaeological research (Papadopoulos et al., 2006;Weston, 2001), was used to determine the apparent resistivity of the underlying sediments.It generally affords sufficient vertical resolution to allow structures in the subsurface to be identified, thus determining the location of possible channels or Gezira deposits.The geoelectrical measurements were carried out with 2-or 3-m electrode spacing reaching distances between 44 and 87 m, depending on the number of electrodes used (Table 1).A standard GPS device was used to locate the precise ERT positions (Garmin Overview of drilling locations and the two-dimensional electrical resistivity tomography (ERT) profiles (Database: © Esri Basemap).
T A B L E 1 Name, length, number of electrodes, electrode spacing, and drilling locations of 2D ERT profiles.| 21

GPSMAP 60CSx
).The varying electrode spacings were selected based on the results of previous investigations in the study area (Lange-Athinodorou et al., 2019;Meister, Garbe, et al., 2021) as well as terrain characteristics, causing different resolutions and penetration depths.The differences in terrain elevation were noted manually, although their influence on the ERT results is probably of minor importance as the terrain is relatively flat.
Inversion of the 2D resistivity profiles was performed using RES2DINV x64 ver.4.08.(Geotomo Software-Home, 2017).A quick inversion procedure for 2D ERT measurements was made possible by developing this software based on the smoothing-constrained leastsquares inversion method (Loke & Barker, 1996).A maximum of five iterations were used, performing the final inversion without bad data points or points with a root mean square (RMS) error greater than 80%.The RMS of the ERTs ranged from 2.0% to 10.4%.

| Distribution of sedimentary units
Using the in-field sedimentological investigations, all 15 boreholes were classified into three main lithological units based on their potential depositional milieu (units I-III; illustrated exemplarily for boreholes A4 and C1 in Figures 3 and 4).Simplified core stratigraphies are presented with the locations of the drillings in Figure 5 (see Supporting Information: SM_1 and SM_2 for detailed core descriptions and photographs).The different lithological units are described and interpreted as follows: Unit I: In all boreholes, the uppermost section is an anthropogenic layer characterized by varying modern and ancient debris, such as ceramics, limestone, charcoal, and brick fragments, as well as plant and root remains.Its thickness varies between ~290 and ~650 cm.
The texture is characterized by different grain size distributions, with silt or sand predominating.The sediment colors range from light brownish through dark brownish to grayish, depending on the type and number of artifacts.
Unit II: Below the anthropogenic surface layer, a layer of loamy to clayey sediments characterized by dark brown to grayish colors and higher soil moistures follows in all boreholes.The small grain size and dark coloration indicate a high organic content and suggest a fluvial or limnic depositional setting with relatively low flow velocity.These fine-grained sediments contain varying concentrations of anthropogenic debris, as well as limestone fragments in a few drill holes.The thickness of these sediments is relatively homogeneous and ranges between 20 and 170 cm.Geziracover Formation (Pennington et al., 2017).In some boreholes, the deposits of unit III overlie the sediments of unit II.

| Electrical resistivity ranges and distributions
The results and locations of the geoelectrical measurements are illustrated in Figure 6, together with the simplified core stratigraphies of the drillings.Although the resistivity values have a relatively small range between <1 and ~100 Ωm, which makes differentiation between individual layers more difficult, the different lithological units can be roughly assigned to the varying resistivity ranges.In general, resistivity values between ~20 and ~100 Ωm in the upper meters can be assigned with the anthropogenic deposits of unit I. Below this, resistivity values decrease, ranging from ~20 to <1 Ωm, which, in some cases, can be linked with the clayey-loamy deposits of fluvial/limnic origin (unit II), whereas the increasing resistivity values between ~20 and ~100 Ωm at the base of the tomograms can be related to the fluvial sediments of unit III.

| South of Temple of Pepi I (ERT profiles 1 and 2)
The profile ERT 1 extends from northwest to southeast and is located at the southwestern border of the Temple of Pepi I (Figure 6a,g).
Vertical resistivity changes separate the ERT profile into three The lowest section below can be differentiated into a southern section with slightly higher values up to ~100 Ωm and a northern section with values up to ~20 Ωm.In combination with the stratigraphic information from boreholes A1-A3, the higher resistivity values in the upper area can be assigned to the anthropogenic debris layer (unit I).While the underlying low-resistivity layer is likely to be influenced by the fluvial/limnic sediments of unit II, the higher resistivity bottom layer can be associated with the deposits of unit III.
Profile ERT 4 extends from southwest to northeast and is located at the eastern border of the Temple of Pepi I (Figure 6d

| Sedimentary units and ERT surveying
Three different lithostratigraphic units were discovered during the drillings in spring 2022 at the Temple of Pepi I, all of which have already been described and discussed in previous studies of the study area (Lange-Athinodorou et al., 2019;Meister, Garbe, et al., 2021;Ullmann et al., 2019).The differences between these sedimentary units in their grain size composition, moisture, traces of anthropogenic artifacts, and color allow them to be assigned to different depositional environments.
The sediments of the surface layer (unit I), dominated by silt or sand but also containing other grain sizes with coloring ranging from light brown to dark brown to grayish, were predominantly anthropogenically formed.This is confirmed by the large amount of modern and ancient anthropogenic artifacts in this unit, such as ceramic or brick fragments and charcoal remains, and other features such as limestone fragments and plant remains (Lange-Athinodorou et al., 2019;Meister, Lange-Athinodorou, et al., 2021).
Unit II consists of mostly loamy and clayey material of dark brown to grayish coloring, and is characterized by a high organic content, which can be attributed to its genesis within a fluvial or limnic depositional environment with relatively low flow velocity (Ginau et al., 2019) and associated with the Bilqas Formation (Pennington et al., 2017).Such deposits are typical for delta environments, for example, for paleochannels, ox-bow lakes, and cut-offs (Altmeyer et al., 2021;Brown, 1997;Ginau et al., 2019;Toonen et al., 2012).Comparable sediments have already been described for the site of Bubastis, where they were interpreted as infills of former water bodies, that is, canals, in the direct proximity of the Temple of Bastet, due to the basin-like distribution of the deposits and the parallel course of the resulting structures along the temple (Lange-Athinodorou et al., 2019;Meister, Garbe, et al., 2021) (Figure 1c).However, these kinds of Isheru were typical for temples of goddesses and are not expected at a royal veneration, such as the Temple of Pepi I (Gessler- Löhr, 1983).Furthermore, the fluvial/limnic sediments near the Temple of Pepi I are characterized by low thicknesses and lack basin-like structures, so in this case, they are not interpreted as canal sediments.It is more likely that these sediments are deposits of a marshy landscape, the origin of which is explained in the following Section 5.2.
The basal sediments of unit III belong to the Mit Ghamr Formation or the Geziracover Formation (Lange-Athinodorou et al., 2019;Meister, Garbe, et al., 2021;Pennington et al., 2017;Ullmann et al., 2019;Wunderlich & Andres, 1991), characterized by fluvial deposits with different grain size distributions caused by varying depositional conditions within the fluvial delta system during the Pleistocene (Said, 2012(Said, , 2013)).Compared to unit I and unit II, these deposits contain almost no anthropogenic debris.
To extrapolate the results of the stratigraphic analyses to a larger area, geoelectrical measurements were conducted, in addition to the sedimentological investigations.The geoelectrical results are generally in line with the standard literature (Reynolds, 2011;Telford et al., 1990), previous investigations at Bubastis (Lange-Athinodorou et al., 2019;Meister, Garbe, et al., 2021), but not with all the results of the sediment analyses.As the resistivity values are generally very low and the differences are small, it is complicated to assign the tomograms to the stratigraphic units, although the tomograms can be roughly divided into several sections.The coarser-grained sediments of unit I and unit III are mostly characterized by higher resistivity values (>20 Ωm).In contrast, the loamy to clayey deposits of unit II, which tend to have somewhat lower values (<20 Ωm), are often not clearly identifiable.The transition between unit II (values < 20 Ωm) and the Gezira sands of unit III (values > 20 Ωm) can be recognized quite well, with the exception of core A2 in ERT 3, and this is despite the fact that the vertical resolution of the ERT tomograms decreases with depth.The distinction of stratigraphic units based on resistivity values is in some cases consistent with the borings (e.g., cores B5 and C2 in ERT 6).
However, there are further methodological difficulties that become apparent through comparison with the drilling results.The anthropogenic debris layer, for example, occasionally shows significantly lower resistivity values, which is why the transition from unit I to unit II is not always recognizable in the tomograms (e.g., core C1 in ERT 1, core B1 in ERT 2, A1 in ERT 3, core A4 in ERT 4, and cores B6 and C3 in ERT 5).These inaccuracies mean that resistivity values cannot always be unambiguously assigned to the various Compared to the influence of grain size variations, the influence of groundwater appears to be generally small, as the tomograms do not show changes toward moisture-related lower resistivity values with increasing depth (Bai et al., 2013;Telford et al., 1990).
Another limitation of geoelectrical measurements can be erroneously measured values that lead to inversion artifacts during subsequent data processing, which are noticeable by markedly deviating resistivity values.In the ERT 6 tomogram, there is a small zone in the southeastern area with significantly lower resistivity values than in the surrounding area, which is interpreted as such an inversion artifact (Hauck & Mühll, 2003;Rings et al., 2008).
Overall, the ERT measurements provide good insight into the areal distribution of the sedimentological units in the subsurface.
However, a trustworthy interpretation of the data is only possible in conjunction with the stratigraphic results of the boreholes, which clearly provide the more reliable data regarding the transitions between different lithostratigraphic units.

| Holocene landscape reconstruction
Based on the sedimentological investigations, the Holocene landscape evolution in the vicinity of the Temple of Pepi I in ancient Bubastis can be described as follows (Figures 7 and 8).
During the late Pleistocene, the Nile Delta was influenced by a (braided) Prenile regime, depositing medium-coarse sands (with some finer layers) of the Mit Ghamr Formation, occasionally containing pebbles or clayey lenses (Figure 7a).The associated sediments of unit III therefore record a variety of depositional processes that likely occurred during the late Pleistocene (Pennington, 2017).It is part of this unit that usually forms "turtlebacks" or "Geziras," where its top surface rises above the modern-day floodplain surface (Butzer, 1976;Pennington, 2017;Said, 2012) (Figure 7a).
In the surroundings of the Temple of Pepi I, we find atop these sediments loamy-clayey deposits of unit II, which are interpreted as representing Holocene deposits (Bilqas Formation) of a swampy-marshy landscape or even a small lake for a number of reasons.The extremely fine-grained nature of the deposits suggests deposition in very slow-flowing or standing water, while the existence of large amounts of vegetation is indicated by the darker sediment colors of the sediments, most likely influenced by considerable amounts of organic matter (Pennington et al., 2017).
In contrast to the surroundings of the Temple of Bastet (Meister, Garbe, et al., 2021)  728 B.C.E.), so the Isheru canals were most likely built during the early settlement and temple phases and then used for several centuries to millennia (Meister, Garbe, et al., 2021).Due to the low thickness of the fluvial/limnic deposits in this area, however, it can only have been the marginal area of such a canal.Moreover, this potential canal was most likely artificially filled with surrounding sediments at the end of the New Kingdom at the latest, as indicated by the large amount of Old Kingdom pottery contained in the anthropogenic layer of unit I in core A6.

| CONCLUSIONS
The objective of this study was to reconstruct the landscape around the Temple of Pepi I during the Holocene.The intention was to investigate whether the Temple of Pepi I was also surrounded by the Late Pleistocene (Said, 2012).Between these two layers, loamy/ clayey sediments are present in all boreholes at a depth between ~0.5 and −2.5 m a.s.l. and a maximum thickness of 1.7 m.Characterized by dark colors, typical for an increasing organic content, these can be associated with a fluvial/limnic depositional environment (unit II) with very low flow velocities (Ginau et al., 2019;Said, 2012).
Location of selected ancient and modern cities in the Nile Delta with ancient and modern Nile branches.(b) Location and extent of ancient Bubastis in Zagazig with possible Nile branch courses after Bietak (1975) and Ullmann (2020, 2022) (Database: Digital Elevation model of the TanDEM-X-Mission).(c) Current extent of Bubastis with ancient and modern features and the verified canal paths.
Using a vibracorer (Wacker BH 65; Wacker Neuson) with open steel drill heads of 1 m length and 80, 60, and 50 mm diameter, 15 percussion boreholes were drilled.Drilling continued until the Pleistocene Gezira deposits were reached at a maximum depth of 8 m.The boreholes were drilled in transects running from the southwest to the northeast of the temple to optimally detect possible channel/canal courses or other hydrogeographical features.The locations of the boreholes were determined using a standard GPS device (Garmin GPSMAP 60CSx).The altitude given in meters above sea level (m a.s.l.) was measured using an optical leveling instrument (Leica TS06; Leica Camera) and based on a local reference system, launched by the archaeological mission of Bubastis in 2018 (Lange-Athinodorou et al., 2019).Based on archaeological evidence, the ancient floor level of the Temple of Pepi I is situated at 3.4 m a.s.l.
Unit III: In the lowermost layer of all boreholes, medium to coarse sandy sediments with varying contents of gravel occur, often alternating with clayey fine sandy material.Depending on the dominant grain size, we refer to them hereafter as Gezira sands or Gezira clays.While the Gezira sands are composed of sands, the Gezira clays contain either strongly clayey sand or strongly sandy clay.The main difference between the Gezira clay and the unit II sediments is a very sandy component in the Gezira clay.These Gezira deposits usually include no anthropogenic features and are yellowish to grayish-blue in color, depending on the groundwater influence.Generally, the deposits of unit III are of fluvial origin, most likely of Pleistocene age, and associated with the Mit Ghamr Formation or the F I G U R E 3 Core stratigraphy of A4 showing the three major lithological units (a); anthropogenic surface layer (unit I), loamy to clayey fluvial/ limnic sediments with little cultural debris (unit II), and the Pleistocene Gezira deposits (unit III).Limestone fragments (b); pottery fragments (c); loamy to clayey fluvial/limnic sediments (d); Pleistocene Gezira sands (e); and Pleistocene Gezira clay (f).The white striped area marks the collapsed sediments.Photos: P. Garbe.
Transect A extends about 50 m south to east of the Temple of Pepi I and includes six boreholes (Figure5a,d).In all boreholes, finegrained sediments of unit II were detected under a several-meterthick anthropogenic debris layer (unit I).The thickness of unit I ranges from ~290 cm (A2) to ~650 cm (A3).The distribution of the underlying unit II is relatively homogeneous.The thicknesses vary between ~60 and ~130 cm at depths of 0.5 to −2.30 m a.s.l.In borehole A2, unit II is overlain by ca.1-m-thick deposits of unit III.Below the fluvial/limnic sediments of unit II follows unit III.In boreholes A1, A4, A5, and A6, there are segments of unit III with increased Gezira clay content reaching thicknesses between ~20 cm (A4) and ~240 cm (A5).The sediment deposits of transect A contain 19 dated ceramic fragments.Ceramics in the boreholes A1 to A4 can be assigned to the Old Kingdom (ca.2850-2180 B.C.E.), or indeed to the Early Old Kingdom (ca.2850-2570 B.C.E.) and the Late Old Kingdom (ca.2570-2180 B.C.E.).In contrast, the age determinations of the ceramic artifacts in drilling A5 range from the Old Kingdom (ca.2850-2180 BCE) to the Middle Kingdom (c.2055-1650 B.C.E.) and in drilling A6 between the Old Kingdom (ca.2850-2180 B.C.E) and the New Kingdom (ca.1550-1070 B.C.E.).4.1.2| Drilling transect B About 40 m further north to northwest of transect A is transect B with six boreholes, which show a comparable picture to transect A (Figure 5b,d).The uppermost anthropogenic debris layer (unit I) varies in thickness from about 385 cm (B2) to 550 cm (B4).This layer lies on top of relatively homogeneous fluvial/limnic sediments (unit II) found at depths of 0 to −2.5 m a.s.l., which are present in all boreholes of this transect with thicknesses between 20 cm (B4) and 120 cm (B5).In borehole B5, unit II is overlain by ~60-cm-thick fluvial sediments of unit III.Under unit II, fluvial sediments of unit III follow, with clay-rich sections varying in thickness from 45 cm (B6) to 70 cm (B1 and B5).In transect B, 18 ceramic artifacts were dated from all stratigraphic units, but especially from unit I, at depths between ~2.5 and ~3.2 m a.s.l.All fragments can be assigned to the Old Kingdom (ca.2850-2180 B.C.E.) or the Early Old Kingdom (ca.2850-2570 B.C.E.) and the Late Old Kingdom (ca.2570-2180 B.C.E.).Usually, the age of the ceramic fragments increases with increasing depth.4.1.3| Drilling transect C Transect C lies about 30 m north to northwest of transect B. It contains three drillings and shows a similar picture to the other two transects (Figure 5c,d).

F
I G U R E 4 Core stratigraphy of C1 showing the three major lithological units (a); anthropogenic surface layer (unit I), loamy to clayey fluvial/ limnic sediments with little cultural debris (unit II), and the Pleistocene Gezira deposits (unit III).Pottery fragments (b and c); loamy to clayey fluvial/limnic sediments (d); Pleistocene Gezira sands (e); and Pleistocene Gezira clay (f).The white striped area marks the collapsed sediments.Photos: P. Garbe.F I G U R E 5 (a-c) Generalized results of drilling transects A-C in the vicinity of the Temple of Pepi I and their locations (d).The dashed green line marks the floor level of the Temple of Pepi I (3.4 m a.s.l.).The first meters consist of the anthropogenic debris sediments (unit I), reaching thicknesses between 330 cm (C3) and 460 cm (C1).In borehole C2, these sediments are interspersed by two sandy layers of unit III, each a few decimeters thick.At a depth of 0 to −2.5 m a.s.l., fine-grained sediments of unit II follow, reaching thicknesses between 85 cm (C1) and 170 cm (C2).In borehole C3, ~85-cm-thick fluvial deposits of unit III overlay unit II.Below unit II, the fluvial sediments of unit III are found.In boreholes C1 and C2, layers of Gezira clay occur with thicknesses between 30 cm (C1) and 100 cm (C2).Seven ceramic fragments were dated in transect C, mainly from the anthropogenic debris layer (unit I) from depths between ~1 and −2.5 m a.s.l.While the ceramic fragments in borehole C1 can be dated to the Late Old Kingdom (ca.2570-2180 B.C.E.), the ages of the fragments from the other boreholes range from the Old Kingdom (ca.2850-2180 B.C.E.) to the New Kingdom (ca.1550-1070 B.C.E.).
sections.The uppermost layer reaches resistivity values between ~5 and ~35 Ωm.The area below shows slightly lower resistivity values of ~5 to ~15 Ωm, before values in the lowest layer increase again slightly to ~20 to ~50 Ωm.In combination with the stratigraphic information from boreholes B1, B2, and C1, the higher resistivity values in the upper area can be assigned to the anthropogenic debris layer (unit I) and in the lowest layer to the fluvial sands of unit III.The intermediate area with slightly lower values can possibly be associated with the fluvial/limnic sediments of unit II, although it is very complicated to distinguish between the layers because of the marginal resistivity differences.The profile ERT 2 extends from southwest to northeast and is situated at the southern border of the Temple of Pepi I (Figure 6b,g).The ERT tomogram can be divided into several sections due to the different resistivity ranges.The northern part shows resistivity values of up to ~100 Ωm, the southern part between ~5 and 50 Ωm, while in between, values of ~10 to ~30 Ωm are reached.The central section displays a differentiated pattern at higher depths.While in the southern direction, the resistivity values increase with higher depth up to ~40 Ωm, they decrease in the northern direction to ~8 Ωm.Higher resistivity values in the upper areas can be attributed to the anthropogenic debris layer (unit I) when combined with the stratigraphic data from boreholes B1-B3, and higher resistivity values in the deeper areas in the southern direction can be attributed to the deposits of unit III.In the central area in the deeper layers, only low resistivity values of ~8 Ωm are reached.The fluvial/limnic sediments of unit II are not indicated by lower resistivity values.4.2.2 | East of Temple of Pepi I (ERT profiles 3 and 4) The profile ERT 3 extends from southwest to northeast and is positioned at the southeastern border of the Temple of Pepi I (Figure 6c,g).Because of the vertical differences in resistivity values, the ERT profile can be divided into three sections.The topmost layer displays resistivity values between ~8 and ~50 Ωm.This is followed by a layer reaching low-resistance values between <1 and ~8 Ωm.
,g).Vertical resistivity changes separate the ERT tomogram into three segments.In the upper meters, resistivity values between ~5 and ~50 Ωm are reached, which can be associated with the anthropogenic debris layer (unit I).Below this follows a low-resistivity section several meters thick, with values ranging from ~8 to <1 Ωm, which, based on the stratigraphic characteristics of borehole A4, may also be influenced by the anthropogenic sediments (unit I).At the base, resistivity values increase with depth up to ~100 Ωm, which can be linked to the sediments of unit II and unit III.4.2.3 | North of Temple of Pepi I (ERT profiles 5 and 6) The profile ERT 5 extends from northwest to southeast and is situated at the northeastern border of the Temple of Pepi I F I G U R E 6 Two-dimensional electrical resistivity tomography (ERT) profiles combined with drillings and their locations (g).The profiles ERT 1 and 2 are situated south of the Temple of Pepi I (a and b); profiles ERT 3 and 4 are located east of the Temple of Pepi I (c and d); and the profiles ERT 5 and 6 are positioned north of the Temple of Pepi I (e and f).The dashed black line marks the ground level of the Temple of Pepi I (3.4 m a.s.l.).RMS, root mean square.(Figure 6e,g).The ERT tomogram can be differentiated into three layers due to the different resistivity ranges.The top layer, several meters thick, displays resistivity values of ~3 to ~10 Ωm.This is followed by a low-thickness section reaching values between ~10 and ~20 Ωm.In the lowest area of the tomogram, the resistivity values increase and display resistivities of ~80 Ωm.Although the values in the upper section are very low, this can be assigned to the anthropogenic debris layer (unit I).While the higher resistivity section in the lower layers can be assigned to the fluvial deposits of unit III, it is complicated to relate the low-thickness middle layer to the fluvial/ limnic sediments of unit II because of the low resistivity changes.The profile ERT 6 extends from northwest to southwest and is positioned at the northeastern border of the Temple of Pepi I (Figure 6f,g).The different resistivity values divide the ERT profile into three sections.The southern section shows resistivity values ranging from ~2 to ~100 Ωm, while the northern section shows consistently high resistivity values of up to ~100 Ωm.These are interrupted by a central section that displays values between ~10 and ~50 Ωm in the upper meters.Below that, values in the central segment decrease to ~20 to ~5 Ωm before increasing again to ~50 Ωm.In combination with the results from boreholes A4, B5, and C2, the higher resistivity values in the upper sections can be associated with the anthropogenic debris layer (unit I) and in the lower sections with the deposits of unit III, while the lower values in the central segment are probably related to the fluvial/limnic deposits of unit II.
This may be caused by the influence of salinity and moisture or grain size variations(Choudhury et al., 2001;Shaaban & Shaaban, 2001), or the fact that the fluvial/limnic sediments of unit II occur with relatively low thickness.The combination of 2-or 3-m electrode spacing and the mostly very thin fluvial/limnic sediments of unit II make them difficult or impossible to detect in the ERT tomograms due to their weak signal.Moreover, the fine-grained Gezira clays of unit III, for instance, should generally have lower resistivity values than the Gezira sands, but probably cannot be detected in the ERT because of their low thickness.Only the Gezira clays with a thickness of 240 cm in borehole A5 can be associated with low resistivity values in ERT 4.
, the spatial distribution and the absence of basinlike structures do not indicate the existence of channels or artificial canals.Rather, the fine-grained sediments of this unit are relatively low in thickness (c.1.5 m) and occur at similar depths areally, indicating that they represent a homogeneous, poorly drained landscape unit at the time of deposition (Figure8).At this time, a depression existed between the Central and Western Kom, which was most likely seasonally or periodically filled with water from the annual Nile floods, forming a marshy landscape before the Fourth Dynasty (Figure7b).Although the ceramics can be displaced by natural and anthropogenic processes such as fluvial transport or relocation processes, they can be used as a suitable proxy for dating the stratigraphic units.The general presence of pottery fragments in the fluvial/limnic deposits of unit II in almost all transects dating to both the Early Old Kingdom (ca.2850-2570 B.C.E.) and the Late Old Kingdom (ca.2570-2180 B.C.E.) proves that this depositional environment was influenced by human activity during this period.Based on the pottery finds in the overlying anthropogenic deposits of unit I, most of which date to the Old Kingdom, and the observed construction activities, the area apparently fell dry during the Early Old Kingdom, where it was used as a construction site for a governor's palace during the Fourth and Fifth Dynasties (ca.2550-2350 B.C.E.) (Lange, 2006; Lange-Athinodorou & Es-Senussi, 2022) and later for the Temple of Pepi I during the early Sixth Dynasty (ca.2300-2250 B.C.E.) (Figure 7c,d).The swampy or marshy area was thus either drained by human activities during the Old Kingdom to be used for cultic and settlement activities or dried up naturally through the ongoing process of aridification after the African Humid Period (Kuper & Kröpelin, 2006).However, a precise date for the drainage cannot be determined without further geoarchaeological investigations (Figure 7b-d).Excavations about 50 m west of the Temple of Pepi I have shown that a cemetery of the First to Second Dynasty (ca.3100-2686 B.C.E.) was situated directly on top of a Gezira hill, which rises considerably in a westerly direction to a maximum of 3.74 m a.s.l.(Ashmawy, 2021) (Figure 7b).The relatively rapid rise of the western Gezira hill, the location of the swampy/marshland landscape in the depression between the Western and Central Kom, and sedimentation processes explain why the deposits of unit II are between ~0.5 and −2.5 m a.s.l., significantly below the ground level of the Temple of Pepi I at ~3.4 m a.s.l.(Figure 7d).By the time of the 22nd Dynasty and the peak of importance of the Temple of Bastet (ca.900-800 B.C.E.), the depression between the Western and Central Kom was filled with anthropogenic sediments of unit I (Figure 7e).In addition, the occurrence of Pleistocene Gezira deposits (unit III) on top of the fluvial/limnic deposits of unit II, as in boreholes A2, B5, C2, and C3, suggests anthropogenic sediment relocation, especially as anthropogenic artifacts were present in all relocated layers.The redistribution of sediments in this area was likely the result of digging and leveling F I G U R E 7 Generalized model of the landscape development in the study area for different time slices: the Late Pleistocene (a); the Early and Late Old Kingdom (b-d); the peak of importance of the Temple of Bastet during the 22nd Dynasty (e); and the present time (f).activities during the construction of the buildings and settlement activities.By the present time, the former depression was completely filled with sediments or even slightly raised by anthropogenic deposits.The surface structures in the area of the Temple of Bastet show no evidence of the Central Kom, while the Western Kom, west of the Temple of Pepi I in the area of remains of the First to Second Dynasty cemetery (ca.3100-2686 B.C.E.), is still exposed on the surface (Figure 7f).

5. 3 |
Connection to the canals of the Temple of Bastet One of the initial objectives of this study was to clarify whether there were once canals east of the Temple of Pepi I that were connected to the sacred Isheru canals of the Temple of Bastet.This hypothesis could neither be confirmed nor rejected by the results of the sedimentological and geoelectrical investigations.As for the southern canal of the Temple of Bastet, it is certain that there was no connection in the direct proximity of the Temple of Pepi I and the canal therefore probably ran further south.In the northeastern corner of the survey area of the Temple of Pepi I, a connection to the northern canal of the Bastet temple cannot be completely ruled out.This is due to pottery fragments from the Middle Kingdom (ca.2055-1650 B.C.E.) and the New Kingdom (ca.1550-1070 B.C.E.) found in boreholes A5 and A6.While the sporadic incorporation of Middle and New Kingdom pottery in the upper sedimentary layers (unit I) of cores C2 and C3 could be the result of ancient and/or modern settlement activities, a possibility alsosupported by the relocated Gezira deposits within these sedimentary sequences, pottery of this age is also found in the loamy-clayey deposits of unit II in the boreholes A5 and A6.One possible explanation is that this area may have been at least temporarily connected to the northern Isheru canal of the Temple of Bastet, which is documented to have been in use until at least 450 B.C.E., although its construction date remains unknown(Lange-Athinodorou et al., 2019;Meister, Garbe, et al., 2021).Ceramic fragments within the southern and northern Isheru canal roughly date from the Old and Middle Kingdom (ca.2700-1650 B.C.E.) to a period before the 25th Dynasty (before ca.

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I G U R E 8 Overview of the detected swampy-marshy landscape in combination with the locations of the boreholes and the two-dimensional electrical tomography resistivity (ERT) profiles.canals that were potentially connected with the Isheru canals of the Temple of Bastet.To investigate the temple surroundings, 15 boreholes and six 2D geoelectrical measurements were undertaken to the south, east, and north of the Temple of Pepi I in spring 2022.Mostly coarse-grained sediments from the anthropogenic debris layer (unit I) dominate the upper meters, whereas the basal layers of the boreholes consist of Gezira deposits of the Pleistocene (unit III), which are typical for the region.These fluvial deposits are characterized by different grain sizes (sands and clays) caused by varying depositional conditions within the fluvial delta system during However, based on the spatial distribution, the low thickness of this layer, and the absence of basin-like structures, no channel(s) or artificial canal(s) could be identified.The sediments of unit II are rather interpreted as deposits of a swampy-marshy environment formed in a depression between the Western and Central Kom (i.e., the temples sites of Pepi I and Bastet), which was probably seasonally or periodically filled with water by Nile floods.The pottery fragments found in unit I and unit II were assigned by in situ dating mainly to the Old Kingdom (ca.2850-2170 B.C.E.), demonstrating that the area was strongly influenced by human activities during this time.This is also in line with the recent discovery of a Fourth to Fifth Dynasty provincial palace (ca.2550-2350 B.C.E.), which was overbuilt by the Temple of Pepi I during the early Sixth Dynasty (ca.2300-2250 B.C.E.).During of the Old Kingdom, the former marshland thus either dried up through natural processes or was intentionally drained and filled with sediments to make the area usable for ritual and settlement purposes.Over time, anthropogenic sediments have increasingly filled the former depression, so that there are no traces of it in today's topography (Figures7 and 8).However, a precise date for the drainage cannot be determined without further geoarchaeological investigations.With regard to the sacred Isheru canals of the Temple of Bastet, no evidence of their continuation could be found in the investigated surroundings of the Temple of Pepi I, even if a former connection in the northeastern area of the site cannot be completely ruled out.Overall, the results provide important evidence for the reconstruction of the Holocene landscape and settlement development in the vicinity of the Temple of Pepi I. To find the connections of the canals of the Temple of Bastet to the ancient Nile branches and to specify the temporal development of the paleolandscape at Bubastis, further geoarchaeological investigations in the wider surroundings of the temple sites are necessary, although this will be extremely difficult due to modern building development.
(Meister, Garbe, et al., 2021)bends in a south-easterly direction, while the northern canal turns in a northerly direction(Meister, Garbe, et al., 2021)(Figure1c).Around 100 m west of the Temple of Bastet is another elevation, the "Western Kom," where temples of the late Old Kingdom for the veneration of the royal Ka of Teti and Pepi I (beginning of the Sixth