594241 HOL0010.1177/0959683615594241The Holocene)Rosen et al. research-article2015 Special Issue: The Anthropocene in the Longue Durée The Anthropocene and the landscape of Confucius: A historical ecology of landscape changes in northern and eastern China during the middle to late-Holocene The Holocene 2015, Vol. 25(10) 1640–1650 © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0959683615594241 hol.sagepub.com Arlene M Rosen,1 Jinok Lee,1 Min Li,2 Joshua Wright,3 Henry T Wright4 and Hui Fang5 Abstract The Yellow River catchment of northern China was central to the rise of complex societies from the first Neolithic farmers through to early states and empires. These cultural developments brought with them rising populations and increasing intensity of land-use. This region provides an important record of landscape changes that mark the development of the Anthropocene in China. Geoarchaeological research in the middle reaches of the Yellow River catchment of Henan Province and eastward to the Si River drainage of Shandong Province illustrates human impact on vegetation and hydrological systems dating back at least until the middle Neolithic Yangshao Period in the mid-Holocene, ca. 7000 yr BP. This research provides geomorphological evidence that early human impact began in the Yangshao period with deforestation, soil erosion, and increased alluviation in the upper catchment of the Yiluo River. The increased alluviation allowed small-scale Neolithic farmers to intensify and supplement their production with rice paddy farming. Further east along the Si River of Shandong Province, Neolithic Dawenkou farmers were intensifying production by taking advantage of the already moist floodplains, but had little impact on the surrounding forests and hillslopes. At the beginning of the Zhou Period (ca. 1000 BCE), farmers along the Si River at Qufu began to intensify production by digging canals into the floodplain, and deforestation of the hillslopes led to the beginnings of widespread floods and silty floodplain buildup, culminating in the massive destructive floods of the later Han Period characterized by thick sand beds. Keywords agricultural intensification, Anthropocene, China, Han Period flooding, land-use, mid-Holocene Received 17 December 2014; revised manuscript accepted 8 June 2015 Introduction The Anthropocene was first introduced as a concept in 2002 by Paul Crutzen (Crutzen, 2002) to emphasize and bring attention to the critical point that human beings have had the same magnitude of impact on this planet’s natural systems as non-human geological transitions, and astronomical cycles which drive the change to new geological epochs. It was intended not to be purely a taxonomic delineator, but also a wake-up call to administrators and planners that we were quickly approaching a tipping point of no return in the manner in which we as a species have driven major changes to all segments of the earth’s natural systems. This article by Crutzen initiated a debate which in part focused on topics of geological nomenclature. Some researchers remained on message and pointed to the more urgent goal of drawing the public’s attention to the dramatic effects of human impact on the planet in the past few hundred years, primarily beginning with the Industrial Revolution in 18th-century Europe. However, in order to keep the Anthropocene in perspective, there are larger issues relating to who we are as a species, our dependence upon profoundly altering our habitats in order to exist, and how we can survive in our large numbers without having a damaging effect on the planet in which we live. These lines of inquiry touch directly on the nature of Homo sapiens. The only way we can resolve such issues is to reach back through deep time using historical accounts and archaeological data to examine our relationships with the natural world throughout our cultural development. Researchers such as Ruddiman (Ruddiman et al., 2008) have shown that we can trace the beginnings of major human impact on atmospheric gases such as methane (CH4) back to around 5000 BP with the spread of paddy fields in Southeast Asia. But other human impacts are also evident from much earlier times in the archaeological and paleoenvironmental records. Smith and Zeder argue that human impact on the earth became most significant with the origins and spread of crops and domestic herds as 1Department of Anthropology, The University of Texas at Austin, USA of Asian Languages & Cultures and Department of Anthropology, University of California, Los Angeles, USA 3Department of Anthropology, Oberlin College, USA 4Museum of Anthropology, University of Michigan, USA 5Department of Archaeology, Shandong University, China 2Department Corresponding author: Arlene M Rosen, Department of Anthropology, The University of Texas at Austin, 2201 Speedway, Stop C3200, Austin, TX 78712, USA. Email: amrosen@austin.utexas.edu Downloaded from hol.sagepub.com at University of Texas Libraries on November 1, 2015 1641 Rosen et al. Figure 1. Map showing the locations of the Yiluo River valley, Wangjinglou, and Qufu. agricultural lifeways became the primary means of subsistence for many human communities. This economic orientation, and the enhanced ‘niche construction’ that was integral to agricultural economies began to take hold at the Pleistocene/Holocene transition (Smith and Zeder, 2013). These human activities influenced the composition and distribution of biomes, including forest and grassland species, as well as erosive land-use practices that impacted river and stream catchments, significantly altering the alluvial/depositional regimes of these hydrological systems (see, for example, Abrams and Nowacki, 2008; Anderson, 2002; Dambrine et al., 2007; Dupouey et al., 2002; Heckenberger et al., 2007; Huang et al., 2006b; Yasuda et al., 2000). Over time, a palimpsest of continuously changing landscapes resulted in a deep-time historical ecology with each generation bequeathing altered ecologies onto the next – thus resulting in landscapes that have been profoundly transformed from their pre-human states. An excellent record of such changes comes from northern China and illustrates human impact on vegetation and hydrological systems dating back at least until the middle Neolithic Period in the middle Holocene, ca. 7000 yr BP. In this paper, we will present some of our geoarchaeological evidence which illustrates the magnitude of human impact on vegetation and hydrological systems in China from the middle Holocene Neolithic in northern China along the middle catchment of the Yellow River, through to the late-Holocene of the early Imperial Period in eastern China along the Si River in Shandong Province (Figure 1). Physical setting The middle and lower reaches of the Yellow River are characterized by deciduous broadleaf forests, fertile loess soil (yellow silt), and a temperate climate. Topographically, the area is demarked by the Songshan Mountains and loess tableland to the west and Mount Tai to the east. The Huai River lies at the southern end of the area. It consists of uplands in the west, great plains in the center, and a combination of highlands and alluvial lowlands in the east. The Yellow River rises in the far west of the Tibetan Plateau and flows eastwards across the Loess Plateau before emptying into the Bohai Sea. For much of the Holocene era, the Yellow River meandered over the area, inundating the vast area of the Central Plain (Shen et al., 1989). The Yiluo River valley is located within the middle reaches of the Yellow River catchment, in the southeastern portion of the Chinese Loess Plateau. The Yi and Luo Rivers flow from southwest to northeast through the basin to form a single channel of the Yiluo River, which discharges into the Yellow River. The Songshan Mountains, with an average height of 1000 m, descend to the Yiluo Basin, which is approximately 120 m lower in altitude than the Songshan Mountains. Small tributaries, including the Gangou, Wuluo, and Liu Rivers, flow downward from the mountains to the alluvial region before emptying into the Yiluo River. The landscape of the area consists of a combination of alluvial plains and terraces on loess tableland (Liu et al., 2004). Archaeologically, the Yiluo Basin was the core area of Erlitou culture, throughout which more than 200 sites are distributed on the alluvial plains and loess tablelands (Liu and Chen, 2012). Our third study area is in and around the modern city of Qufu. Qufu is located in the southwest of present-day Shandong Province. The surroundings are characterized by a broad and flat alluvial plain with gentle relief, sloping toward the southwest. At present, the area is situated in the lower reaches of the Si River, which rises in the southern foothills of the Mengshan Mountains and flows through Sishu county and Qufu before emptying into Lake Nanyang. Today, the region is primarily a wheat and maize producing area. It has a temperate, sub-humid monsoon climate, with a mean annual rainfall of 700 mm. The regional climate is affected by the seasonal shifts between the winter and summer monsoons. Due to the monsoonal climate, the majority of the rainfall occurs in the summer months (June–August), accounting for 70% of the annual total (Gongxian County Chronicle Editorial Board, 1991) cited by Liu et al. (2004). This region lies at the northern edge of the summer monsoonal systems, but also receives some precipitation in the winter months from the weaker winter monsoons. Downloaded from hol.sagepub.com at University of Texas Libraries on November 1, 2015 1642 The Holocene 25(10) Paleoenvironmental background Over the course of the Holocene period, there were significant changes in climate, vegetation, and human impact on the landscape in the region of the middle and lower Yellow River valley. These environmental changes have had direct and indirect impacts on the hydrology, vegetation, and landforms of the Yellow River basin. The environmental sequences in China have been related to local-scale environmental changes as well as global climatic events. In general, the regional climate in northern China has been conditioned by the interactions between the winter and summer monsoons (An et al., 2006; Tregear and Tregear, 1980). The East Asian monsoon is a principal determinant of the level of precipitation and therefore, is the most important atmospheric factor affecting lake levels, vegetation, river flooding, and human adaptation in the region. The strength of the East Asian monsoons has changed throughout the Holocene in response to changes of solar insolation caused by alterations of the Earth’s orbital parameters (Feng et al., 2006). In the early phases of the Holocene, around 10,000 BP, there was a general trend of warming and increase in precipitation across East Asia (Li et al., 2004). High temperatures in the high northern latitudes weakened the strength of the winter monsoon and thus enhanced the strength of the summer monsoon. This culminated in the interval of peak warmth and moisture known as the ‘Mid-Holocene Climatic Optimum’ which occurred at about 9000 BP throughout North China in response to the high latitude peak insolation (9000–8000 BP), and lasted until 3000 yr BP (Feng et al., 2004, 2006). The Megathermal episode is identified from sediment sections at various localities of the Yellow River catchment basin. Feng et al. (2004) analyzed bog deposits from Sujiawan and Dadiwan sections in Gansu Province and synthesized existing data to search for the regional pattern of the Holocene Climatic Optimum. Through the analyses of magnetic susceptibility, particle size distribution, carbonate concentration, and pollen from lake sediments, they identified a widespread occurrence of wetland deposits dating from 8000 to 5000 BP. Based on this, they concluded that the Holocene Climatic Optimum, which is characterized by high moisture content in soils, occurred nearly contemporaneously in North China. The Climatic Optimum is also detectable from wind-blown deposits of the Loess Plateau. Since soils develop on stable land surfaces under warm and moist climatic conditions, soil formation in loess deposits is used as a proxy for the mid-Holocene Climatic Optimum. Feng et al. (2006) examined paleosol sequences in northern China and identified four stages of soilforming sequences (10,000–9000; 7500–5000; 4000–3000; and 2700–2000 BP) with 7500–5000 BP being the most pronounced soil-forming phase. An et al. (2000) also documented the bestdeveloped paleosol sequence on the Loess Plateau ranging from 9000 to 5000 BP. These favorable climatic conditions corresponded to dense and diverse ecosystems, as well. A comprehensive palynological study was carried out by Yi et al. (2003) in the Yellow River delta. Through the study of pollen preserved in deltaic sediments, they identified a vegetation dominated by monsoonal evergreen and broad-leaved deciduous forests, and increasingly diverse plant species during the times ca. 9800–4500 BP. These forest species were probably restricted to the littoral zones of streams, since pollen studies from the Yaoxian section in the southernmost portion of the Loess Plateau indicate that shrubs and grassland steppe were the dominant vegetation type on the interfluves throughout the Holocene, with more humid grasslands dominating in the wetter phases (Li et al., 2003). Sediment from the Yellow River delta is another source of climate proxy data, as the formation rate and chemical properties of deltaic sediments reflect sea-level fluctuations and sediment discharge, as well as depositional environments and vegetation of the upper drainage areas (Jiang and Piperno, 1999; Ren, 1992; Saito et al., 2001; Sun et al., 2011). Sun et al. (2011) examined geochemical proxies and molecular biomarkers for sediment cores from the Bohai Sea and documented an increase in organic matter derived from woody plant contents between 6000 and 3800 BP. They attributed this abrupt change to increased vegetation density and soil development under the warm and humid climatic conditions. The mid-Holocene Optimum came to an end around ca. 4000 BP and the climate became generally cooler and drier (Feng et al., 2004, 2006). As summer monsoons were weakened and retreated southward to the Yangzi River, a cool and dry climate regime prevailed in the Yellow River valley (Peng et al., 2005; Xiao et al., 2004). This climatic shift is also evidenced by multiple proxies, including isotope, pollen, and sediment profiles from throughout the Loess Plateau and Yellow Sea deltas (e.g. Peng et al., 2005; Zhou et al., 2004). Pollen data from coastal sediments clearly display a reduction in the percentage of deciduous broad-leaved plants in the arboreal total and an abrupt increase in grass taxa beginning ca. 3800 BP (Sun et al., 2011). Other proxy data also indicate that the cooling episode led to a sparsely vegetated ground surface, increasing channel incision and erosion, and therefore an increase in sediment flux delivered into rivers. It is noteworthy that the landscape changes primarily initiated by climate conditions were further amplified by anthropogenic activities. Rapid population growth during the late-Holocene has increasingly put high pressure on regional landscapes. Multiple pollen data have pointed to a sudden replacement of broad-leaved forest to secondary forest (Pinus) at around 4000 BP (Jiang and Piperno, 1999; Sun et al., 2011; Yi et al., 2003). Jiang and Piperno (1999) interpret the increased percentages of Pinus as marking the development of the secondary pine woodland which resulted from human-induced deforestation. Human impacts are also inferred by sediment data from both the Loess Plateau and the coastal delta. Saito et al. (2001) reported a sudden increase in sediment discharge that occurred ca. 3000 BP, which resulted from human interference, such as intensive land-use and deforestation on the Loess Plateau. Xu (2003) also documented an increase of the sedimentation rate in the lower reaches of the Yellow River at 1300 BP, which he interpreted as the result of human-induced soil erosion and land clearance. Results of geoarchaeological investigations Yiluo Basin Henan Province Work on this project began in 2000 with the initial goal of recording archaeological sites and the environmental setting of rising early complex societies in China (Liu et al., 2004; Figure 1). In the course of geoarchaeological research, Rosen identified evidence for the earliest paddy fields in this region, as well as major human impact on vegetation and hydrological systems beginning in the middle Neolithic Yangshao Period from 5000 to 3000 BCE (Rosen, 2007, 2008). Previous to this period, the first significant settlement in the Yiluo catchment occurred during the early Neolithic later Peiligang Period (6000–5000 cal. BCE). At this time, semi-sedentary forager-farmers moved into this region with a tradition of gathering wild resources and low-level cultivation (sensu Smith, 2001) of millet (Lee et al., 2007). Their settlements were sparsely scattered across the landscape and according to the geoarchaeological record, they had a minor impact on vegetation, and caused very little hillslope erosion (Rosen, 2008). This first settlement occurred during the early phases of the period often referred to as the Holocene Climatic Optimum, when the summer monsoonal Downloaded from hol.sagepub.com at University of Texas Libraries on November 1, 2015 1643 Rosen et al. systems were strong and pushed further to the north in the context of warmer and moister conditions. Following this initial settlement, the Yangshao Period farmers moved into the region bringing with them a tradition of rice cultivation in addition to the more prevalent millet cultivation. This was also the period in which increased rainfall from stronger mid-Holocene monsoon systems coincided with growing populations and significantly increased deforestation and subsequent soil erosion (Rosen, 2007, 2008). Geoarchaeological evidence from this region shows an important interaction between human-induced soil erosion beginning with the Yangshao settlements, rapidly increasing alluviation in the drainages along the valley bottoms, and the beginnings of rice paddy farming in this area which is well outside the range of the natural habitat of wild rice, and distant from the region where the earliest rice was first cultivated (Crawford, 2006; Fuller et al., 2008, 2009; Liu et al., 2007). To make the point bluntly, the deforestation and subsequent hillslope erosion increased alluviation in the valley bottoms, leading to favorable conditions for paddy construction and the production of rice in this region. It is an excellent example of early farmers altering the landscape and hydrological systems to create a situation which was economically favorable to a developing agricultural economy (Rosen, 2008). This active valley alluviation and paddy-field construction continued to occur throughout the Yangshao Period and well into the late Neolithic Longshan Period (3000–2000 BCE). However, after around 2000 BCE, the hydrological systems began to change and long-term stream incision dominated the regime in this upper catchment area. This shift in stream regime coincided with the rise of the first state society in China, with its center at the large town of Erlitou located along the Yiluo River, a major tributary to the middle catchment of the Yellow River (Liu et al., 2004). The incision and downcutting carved out the valleys to a depth of around 15 m in the upper catchment of the Yiluo Basin. The trigger for this phase of downcutting may have been at least in part related to the beginnings of drier conditions that accompanied the late-Holocene, and the natural adjustments of the hydrological cycle to the weakening of the summer monsoons. The effect on human agricultural systems was to remove much of the irrigable land on the narrow valley bottoms of the upper catchment. This would have altered the agricultural economies of the smaller villages and towns in this region by removing the flat marshy floodplain where paddies could be easily constructed, and making it more difficult to cultivate a crop of rice. Geoarchaeology of Wangjinglou Moving to the middle reaches of the Yellow River catchment, the geological section at the early Bronze Age Erlitou/Erligang site of Wangjinglou (N34° 26′ 53.2″, E113° 43′ 05.9″) provided insights into the history of alluvial activity and human impact on the hydrology further downstream. This site is located 55 km south of the current channel of the Yellow River, within the modern city of Xinzheng, about 100 km southeast of the early Bronze Age site of Erlitou. As the center of the first state society in China, Erlitou is associated with a major increase in population in this area. The Wangjinglou sediment section is located at the edge of the ancient town, at the interface between the archaeological site and the ancient floodplain (Figure 2). The whole Wangjinglou sediment section gives us insights into the landscape history of this lower/middle portion of the Yellow River catchment. The section begins at the base with a massive sandy silt layer that appears to extend about 10 m down to the modern river channel. This sand-rich deposit seems to derive from streams that meandered over a broad floodplain. Subsequently, the alluviation waned and the landscape was stabilized to form a pre-Yangshao paleosol appearing in Unit 5. The paleosol unit is characterized by a high organic content and high magnetic susceptibility readings, indicating soil developed under prolonged stable conditions. It is thus probable that at the time of Unit 5, the small river that runs at the base of this site moved to the other side of the valley and stopped flooding this area for millennia. Although there are no dateable materials found from the unit, the soil sequence closely resembles mid-Holocene paleosols observed at other localities in the Yellow River valley, especially the paleosol identified as associated with Peiligang early Neolithic deposits in the Yiluo Basin (Feng et al., 2004; Huang et al., 2006a, 2007; Rosen, 2008). Therefore, we assign this unit to the early part of the mid-Holocene Climatic Optimum when the climate was warmer and moister, but before there was a major human impact on this area in the form of deforestation and resulting hillslope erosion. Above this paleosol, Yangshao people occupied the site and left behind the pit containing fragments of their ceramics (Unit 4). But unlike the Yiluo Basin, their impact on the hydrology of the stream system here appears to have been minimal. In the subsequent early Bronze Age Erlitou times, the occupants of Wangjinglou built a rammed earth wall (Unit 3), and the site was occupied until the early Iron Age Eastern Zhou Period. During this time, a fortification wall was constructed on top of the rammed earth walls. Finally, a subsequent flood cut into and destroyed part of the early Bronze Age fortification and deposited the silts shown in Unit 2. Our field observations and grain-size analysis indicate that Unit 2 consists of several layers that are different in particle size and sediment characteristics. The lower portion of Unit 2 is dominated by finer-grained silt lamina that was sourced from a suspended sediment load in a floodwater overbank flow. This silt-dominated layer is overlain by sandy alluvium. On top of the section is sandy silt alluvium (or possibly colluvium) mixed with ceramic sherds dating to the later Eastern Zhou Period. These finely laminated sediments indicate low-energy overbank flow that is often associated with levee deposits. Importantly, they are indicators of a renewed destabilization of the alluvial system. It is highly likely that this is a result of human-induced soil erosion resulting from renewed deforestation in the upper catchment due to ever-increasing population and growing extensive agricultural systems during the Zhou Period. In summary, the geological section at Wangjinglou shows that the rammed earth walls from the Erlitou Period are blanketed by later period finely laminated alluvial sandy silt, dated by ceramic inclusions to the Eastern Zhou Period or later. These floodwater sediments also directly overlay an early Holocene paleosol which is a sign of a stable land surface from Neolithic times until the Eastern Zhou Period. The paleosol was cut by pits containing Yangshao Period pottery, which is indicative of the first Neolithic settlement in this region. Interestingly, however, unlike the upper catchment of the Yiluo Basin, the alluvial system of the tributaries to the Yellow River in this vicinity was stable during the Neolithic, suggesting that the sediment load which increased because of human impact on the hillslopes further upstream in the Yellow River system did not impact this middle zone until well into the late Bronze Age. Jing et al. (1995) also recorded stable land surfaces during the Neolithic Periods from the lower Yellow River. Geoarchaeology of Qufu We were able to obtain further information about human impact on landscape and hydrology of the major river systems that flow from west to east in northern China from our work in Shandong Province in the area around Qufu (Figure 3). Qufu was the seat of a major regional center dated to the Zhou Period, and it supported a palace complex, rammed earth fortifications, and a large population. It is also notable as being the city in which Confucius and his students lived and operated in the 6th century BCE. We conducted Downloaded from hol.sagepub.com at University of Texas Libraries on November 1, 2015 1644 The Holocene 25(10) Figure 2. Grain size, magnetic susceptibility, and Loss on Ignition data for the Wangjinglou section. Figure 3. Locations of geological sections in Qufu. geoarchaeological investigations in this town and its surroundings using a simple but highly effective strategy of ‘crane chasing’ (originally suggested by H Wright), in which we located major modern-day building sites of hotel, apartment complex, and shopping center construction, and took advantage of the deep excavation pits, sometimes around 6–10 m deep, to examine elements of landscape history of this region. This has proven to be a highly effective means of extensive geoarchaeological survey Downloaded from hol.sagepub.com at University of Texas Libraries on November 1, 2015 1645 Rosen et al. Figure 4. Photo of Wanjia geoarchaeological section in Qufu, showing Zhou Period canal features cut into the early/midHolocene backswamp sediment, and subsequent late-Holocene flood deposits. across the town of Qufu. This allowed us to conduct an intensive study of deep sections from the modern-day surface extending down well into the Pleistocene sediment deposits. In most cases, the period of time spanning the Holocene consisted of sediment sections in the upper ca. 6 m of deposits, and we were fortunate enough to find these deposits and dateable material within them from almost all of the sections we investigated across the town. Qufu is located in the present-day Si River drainage in the southwest part of Shandong Province. Since it is located on the broad floodplain of an active river system, it is very sensitive to hydrological changes caused by climate and human land-use in the surrounding catchment. The Pleistocene record can be used as a base-line indicating very minimal human impact on the surrounding landscape. This Pleistocene record consists of undated sets of well-sorted river sands deposited as bars within a broad meandering stream, and thick very clayey red or gleyed floodplain deposits. There are many sand units that show evidence of strong gley as well as units of iron pan formations. These Pleistocene deposits extend down for at least 30 m, based on cores and core logs taken by engineering geologists prior to the construction of the Shangri-La Hotel in central Qufu (notes of cores on file at the Environmental Archaeology Laboratory, Anthropology, University of Texas at Austin). These deposits indicate a very active river regime that was probably driven by strong summer monsoons of interglacial periods, punctuated by weaker summer monsoonal activity in the cooler/drier glacial episodes, as well as the placement of the meandering river as it migrated across the broad floodplain of the Pleistocene Si River. The Holocene deposits represent an abrupt change in the sediment regime. They rest on top of the Pleistocene deposits with an unconformable contact indicating a profound erosional event between the late Pleistocene and the early Holocene. This erosional contact appears in all of our geological sections around Qufu and could be indicative of the 1300-year interval of the Younger Dryas cold/dry episode that has been recorded in other proxy data sets in China (Li et al., 2004; Liu et al., 2008; Madsen et al., 1998; Porter, 2001; Yi et al., 2003). A lowered Pleistocene sea level might also be responsible, which would have dropped the base level of all of the rivers flowing into the sea, resulting in downcutting upstream. Wherever we find these early Holocene deposits, they are around 2 m thick and typically consist of massive dark-brown clayrich sediments with a strong prismatic soil structure (Figure 4). They indicate a broad slowly accumulating organic-rich marshy floodplain, signaling a return to a stable stream regime in which the Si River system consisted of gentle seasonal flooding and the accumulation of backswamp deposits, most likely on a yearly basis during the period of stronger summer monsoons that accompanied the Holocene Climatic Optimum. Zhuang et al. (2013) reported on floodplain aggradation from the nearby site of Yuezhuang in the lower Yellow River catchment, also in Shandong Province. They found a series of alluvial episodes punctuated by periods of stability. The stable floodplains corresponded with phases of Neolithic occupation. Given this more stable stream regime, we can postulate a landscape containing forested uplands with shrubs and gallery trees in the valley bottoms. This vegetation was not greatly impacted by the presumably small populations of foragers and lowlevel farmers that might have lived here in the early Neolithic. We identified the first significant human impact on the river valley in the deep section recorded under the site of the ShangriLa hotel. Here we found the same early Holocene dark-brown clayey floodplain deposits that we identified within all of the sections under modern Qufu. The marshy backswamp deposits had been cut into U-shaped features, possibly indicative of canals for drainage or for irrigation. These channels were subsequently filled with gleyed sandy silt deposits that were dated by 14C to cal. 3270–2910 BCE (4406 ± 28 BP; ZK3403; Upper canal fill – ca. 6 m below surface) and cal. 3630–3370 BCE (4701 ± 28 BP; ZK3404; Lower canal fill – ca. 6.2 m below surface), coinciding with the middle Neolithic Dawenkou Period (equivalent to the Yangshao Period of the Yiluo Basin). This was a time of growing populations and incipient complex societies consisting of a network of walled-towns and villages. These populations were beginning to impact the landscape and floodplains of this region in significant ways, but it is likely that they still had only a very minimal effect on the upland hill country that surrounds the Si Basin. We postulate this based on the lack of evidence for significantly increased sediment yields that would constitute evidence for soil erosion, and the lack of indicators for a rapid increase in flood deposits. In all of the four deep geological sections we worked on within Qufu, we found similar sediment sections showing this sequence of changes from Pleistocene deposits to Holocene backswamps, and then a cessation of backswamp development during the Neolithic Dawenkou Period. The early Holocene stream system consisting of a stable regime of slow floodplain accumulation lasted for several thousand years of the early to mid-Holocene, preceding the Dawenkou Period occupation. It coincided with the episode of strong summer monsoons, and its cessation corresponded to the weakening of the monsoonal system, and resulting reduction of stream flow and smaller, more constrained overbank flooding. The construction of canal-like features into the dark-brown marshy deposits signals the end of this alluvial regime of gentle overbank flow and backswamp formation. Archaeologically, we have no evidence of further interference with either the hydrological regime of the Si, or the surrounding mountain vegetation throughout most of the roughly 1500-year period from the beginning of the Bronze Age around 2000 BCE until the beginning of the early Iron Age Zhou Period (1046–256 BCE; Rapp and Jing, 2011). In this portion of the Si floodplain, we found several instances of both Dawenkou and Zhou Period ceramic fragments mixed together within the uppermost 10 cm of the dark-brown clayey deposits of Unit 4. This strongly suggests that there was little hydrological activity from the Si which would have impacted this portion of the floodplain. This would indicate a relatively stable stream system that remained within the confines of the main channel with little overbank flow or downcutting. If this is a representative picture of the Si stream regime, it indicates that throughout the early and mid-Holocene, and well into the lateHolocene, there was little anthropogenic impact on this region of eastern China. The lack of human impact coincides with the reduction in population and settlement in the lower Yellow River Downloaded from hol.sagepub.com at University of Texas Libraries on November 1, 2015 1646 The Holocene 25(10) Figure 5. Grain size, magnetic susceptibility, and Loss on Ignition data for the Wanjia section. Although Sample WJ-15 appears to have a high sand content, it actually consists of almost pure clay, with sand-sized particles of flocculated clay conglomerates. valley during the late Neolithic and early Bronze Age (Underhill et al., 2008). All of this changed rapidly and quite dramatically with the early Iron Age in the Eastern Zhou Period, and even more markedly and more extensively with the subsequent Han Imperial Period. All of our four geological sections from Qufu and our one geological section from the Nishan Mountains north of Qufu demonstrate this profound change in stream regime quite clearly. The full sequence is best described and analyzed in our geological section from the Wanjia neighborhood in Qufu (Figures 4 and 5). This is located just across a main road from the now-completed Shangri-La Hotel. The base of the Wanjia section clearly shows how the early/mid-Holocene dark-brown backswamp deposits were cut by a series of canal-like features. The upper 10 cm of this deposit (Unit 4) also contains a mix of late Neolithic and Zhou Period sherd fragments. Unlike the Shangri-La Section, the sandy/silty alluvium which fills these canals (Unit 3b) returned 14C dates of 921–831 cal. BCE (2740 ± 20 BP; UCI AMS#131664) and 1005–900 cal. BCE (2795 ± 20 BP; UCI AMS#131665). This is consistent with the Zhou Period, suggesting a similar type of land-use and canal use from the middle Neolithic to the early Iron Age indicating a long period of stability on this surface between the Dawenkou and Zhou Periods. Above Unit 4, and the canal features, there are several meters of lighter brown silts signaling the renewal of overbank flooding (Unit 3a) from the Si River. These deposits indicate an abrupt change in the stream regime from a very stable system with low sediment yield, gentle overbank flow events, and backswamps, to Downloaded from hol.sagepub.com at University of Texas Libraries on November 1, 2015 1647 Rosen et al. Figure 7. Photograph of Han Period sandy alluvium at Nishan, showing graded and cross-bedded sands. Figure 6. Grain size, magnetic susceptibility, and Loss on Ignition data for the Nishan section. one of a rapidly alluviating system that built up meters of sediment just within the time period of the Zhou settlement. The brown color and composition of the deposit suggests that the source of sediment derived from former soils on the hillslopes of the upper catchment of the Si River and its surrounding tributaries. As such, it indicates the first stages of massive soil erosion probably due to the rapid expansion of population into these localities, deforestation for building, industry, and agriculture, and erosive agricultural practices during this period. In two of our geoarchaeological sections (Wanjia and CGL – not discussed in this paper), these brown floodplain silts contained in situ roof tiles, pits, and a possible collapsed farm house all dating to the Zhou Period, showing that populations at that time period were farming and conducting other activities at intervals on that floodplain. It is likely that by the end of the Zhou Period, the upper catchment was completely stripped of its soil cover deep into the B-Horizon in much of the area surrounding Qufu. The evidence for this determination comes from the subsequent Han Period sediment deposits which are almost devoid of silt and clay, and composed primarily of sandy sediments suggesting a source material of parent rock or the exposed C-Horizon and regolith under the soils that were previously eroded during the Zhou Period occupation. The upper catchment of the Si River extends into the Nishan Mountains (Figure 3). Here, we have a geoarchaeological section that illustrates very clearly the coarse nature of the flood sands, suggesting a sandy sediment source with no overlaying soil deposits at the time of entrainment (Figures 6 and 7). The Nishan section has a counterpart with equally thick Han Period alluvial sediments down on the floodplain at Qufu, where we recorded an exposure at Qufu Section 1 (QS1; N35° 33.078′, E116° 58.597′). At QS1 (Figure 8), the basal layer, Unit 5, from 660 to 690 cm below the modern surface (temporally and stratigraphically equivalent to Unit 4 from Shangri-La and Wanjia) is a dark-brown backswamp deposit that is equivalent to early Holocene basal layers found in all of the other sections located around the modern town of Qufu. Directly above this, Unit 4 is a lighter brown silty deposit that is stratigraphically and lithologically similar to the deposits that have been dated by 14C to the Zhou Period and contain Zhou Period pottery in the other Qufu sections. Overlaying this Zhou Period floodplain is a deposit (Unit 3) composed of at least 2 m of thick fluvial sands with Han Period sherds resting at the base. The sands are well-sorted with crossbedding near the top and graded bedding in some locations. This deposit is likely related to the well-documented episodes of Han Period flooding, and the character of the grain-size and sedimentary structures indicate that these flood deposits were laid down by well-sustained and powerful flows. The upper two units of QS1 show a return to low-energy floodplain deposits and contain medieval pottery in them. Han Period flooding is well-known from historical documents which record major episodes of destructive floods that devastated whole towns and villages along the Yellow River. Kidder et al. (2012) have reported on the geoarchaeological evidence for these ancient catastrophic floods in the Han Period from the site of Sanyangzhuang along the middle reaches of the Yellow River. Discussion If we combine the results from Huizui, Wangjinglou, and Qufu, we have a picture of human impact that varies in intensity and degree depending upon the region and the location within the catchment. In the Yiluo Basin at the middle reaches of the Yellow River, the deforestation and resulting impact of the hydrological systems began relatively early – within the middle Neolithic Yangshao Period when large numbers of farming villages began to appear in the region. Unlike the Peiligang inhabitants, they were fully invested in agriculture and had more intensive farming systems including limited-scale rice agriculture (Lee et al., 2007). The deforestation associated with this settlement contributed to major soil erosion, higher sediment yields, and increased buildup of clayey silts on the valley floors. The alluvium on the valley floors made an important contribution to farming systems by contributing a much broader area for wet floodwater farming and paddy construction. These alluvial soils were water-logged, and with a small amount of canal and basin construction the water could be retained for the cultivation of rice and other moistureloving crops. This situation ensued throughout the Yangshao and subsequent late Neolithic Longshan Period (Rosen, 2008). However, we could not detect this Neolithic alluvial episode further downstream, and it is possible that either the sediment remained for the most part in storage in the upper catchment of the smaller tributaries of the Yiluo River, or possibly the sediments that made it further downstream were simply buried by tens of meters of subsequent alluvium along the Yellow River system. Downloaded from hol.sagepub.com at University of Texas Libraries on November 1, 2015 1648 The Holocene 25(10) Figure 8. Grain size, magnetic susceptibility, and Loss on Ignition data for the Qufu section. The earliest alluvial events we detected further downstream are the floodplain deposits that overlay both the in situ Yangshao surface and the Bronze Age rammed earth construction at the site of Wangjinglou. Further east, early Iron Age Period alluvium also appears along the Si River at Qufu. This Zhou Period alluvium is superseded by at least 2 m of Han Period flood sands. Conclusion In this study, we identified three distinctive episodes of soil erosion, flooding, and massive alluvial buildup on former stable floodplains in north central China. These are dated to the Yangshao (middle Neolithic) through Longshan (late Neolithic) periods in the upper catchment of the Yiluo River, a tributary to the Yellow River, and massive flood deposits from the Eastern Zhou and Han Periods along the Si River near Qufu in Shandong Province. These deposits indicate destabilized landscapes and are directly related to human impact on the landscape of China. All of these episodes are attributed to major increases in soil erosion caused by both widespread deforestation and the intensification of agriculture that comes with rapidly increasing populations on the landscape. The Neolithic Period flooding was also likely enhanced by the stronger monsoons that brought higher rainfall amounts to northern China during the mid-Holocene Climatic Optimum. However, the monsoons alone were not solely responsible for the build-up of alluvium, since there were strong monsoons and moister conditions during the early Neolithic Peiligang Period as well as in the middle and late Neolithic Yangshao and Longshan Periods, yet significant alluviation only began in the Yangshao Period. Here, we argue that the new alluvial regime which began in the Yangshao Period was a result of purposeful landscape management on the part of middle Neolithic populations who moved into these upper valleys of the Yiluo catchment. The rapid floodplain buildup that accompanied deforestation allowed the construction and management of wellwatered paddy fields and canals, as well as increasing the irrigable farmland as the V-shaped valleys began to fill with fine-grained alluvium (Rosen, 2007, 2008). This situation in which the landscape and hydrology appear to have been carefully managed by Neolithic Yangshao and Longshan populations is in stark contrast to the situation in the Zhou and Han Periods, when massive destructive floods were responsible for the rapid buildup of the floodplains in Qufu. These floods devastated numerous farming towns and villages (Kidder et al., 2012), and in the Han Period particularly, also deposited large quantities of sand on what was once presumably a very fertile floodplain surrounding the ancient town of Qufu. These landscape changes which began in the Zhou Period mark the beginning of the most disruptive and destructive effects on the hydrologies of the large river systems that drain from west to east in China. This human impact has historically led to numerous destructive flooding events which rebounded with catastrophic tolls of human life, livelihood, and property, earning the Yellow Downloaded from hol.sagepub.com at University of Texas Libraries on November 1, 2015 1649 Rosen et al. River the infamous distinction as ‘China’s Sorrow’ (Ball, 2015). This historical ecology of land-use in northern and eastern China is a legacy that continues into the modern era. Acknowledgements We would like to particularly thank Rachel Lee and Wang Huan for help in the field and in the Geoarchaeology Laboratory at Shandong University. Shandong University staff and students were very helpful and accommodating during our field seasons. Brian Damiata prepared and ran the 14C determinations. We also acknowledge support from the Cotsen Institute of Archaeology, and a UCLA Faculty Research Grant to M Li; The Institute of Archaeology, University College London and the Environmental Archaeology Laboratory, Department of Anthropology, University of Texas at Austin supported additional laboratory analyses. We also thank the two anonymous reviewers for their helpful comments and suggestions on an earlier draft of this paper. Funding Fieldwork and analyses were partially funded by the Liching Guest Professor Fellowship from Shandong University to A Rosen, a Henry Luce Foundation for East Asian Archaeology Grant to M Li, and a Ministry of Education of China 111 Project Grant to H Fang. References Abrams MD and Nowacki GJ (2008) Native Americans as active and passive promoters of mast and fruit trees in the eastern USA. The Holocene 18: 1123–1137. An C-B, Feng Z-D and Barton L (2006) Dry or humid? MidHolocene humidity changes in arid and semi-arid China. 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