Characterization of Bedrock Features at Paleolithic and Epipalaeolithic Archaeology of Izeh Plain, Northeastern Khuzestan

Bedrock features, such as mortars, cup-marks, cupules, grooves, slicks, basins, and grinding surfaces, are a type of rock alteration. These features have been observed in Paleolithic contexts and were used in certain regions until the 20th century. Unlike many other categories of archaeological remains, bedrock features have received relatively little scholarly attention. Until recently, there have been only a few focused field projects dedicated to studying them. This is partly because of the challenges in dating these features and identifying their cultural context. This research focuses on investigating bedrock features discovered during an archaeological survey of Paleolithic caves and rock shelters in the Izeh Plain, located in northeastern Khuzestan. These features, which are found on exposed rock ledges and floors of the caves and shelters, do not have a clear association with datable remains. The goal is to understand the morphological variation of these features and determine their relative dating.

Izeh is an alluvial plain situated in the northeastern part of Iran's Khuzestan province. It has an average elevation of 750 meters above sea level and covers an area of 140 square kilometers. This region is a section of the folded foothills of the Zagros mountains, and its plains consist of scattered sediments. Archaeological surveys have revealed the significant potential for studying the Stone Age in Izeh Plain. After Wright's brief visits in the 1970s (Wright, 1979), the exploration for caves and rock shelters in Izeh was resumed and carried on in the 2000s and 2010s. As a result, over 150 caves and rock shelters from the Upper Palaeolithic and Epipalaeolithic periods were documented (see Jayez, 2023). During the most recent survey season, in addition to caves and rock shelters, we also documented 39 rock cut installations, specifically bedrock mortars and basins. These were mostly found in the outer areas of the sites. Similar features have been documented in Late Paleolithic sites in the Zagros region (see Alibeigi, 2013: 53; Conard and Ghasidian, 2011: 36, 40; Heydari-Guran and Ghasidian 2020: 10). At this point, it is not possible to determine an exact date for these findings. They were discovered in open areas outside of caves and rock shelters, so it is difficult to confirm if they are from the same time period as the prehistoric cultural remains.

The bedrock features of Izeh Plain can be categorized into three types: cup-marks (round shallow holes), mortars (round, usually bowl-like and deep holes), and basins (oval or round shallow features), each serving different purposes. Similar features have been mostly reported from Natufian sites, which are found in various geographical and ecological areas. These include the Mediterranean eco-zone, the Negev desert, the Jordan Valley, and the high sandstone mountains in southwestern Jordan (Nadel and Rosenberg, 2010). The large-scale production of human-made bedrock holes became common during the Late Natufian period. The dominant types were deep narrow specimens, as well as smaller and/or shallower examples. During the PPNA, the most common type of feature was the small and shallow cup-mark, often found on slabs placed on house floors. The production and use of these bedrock features continued into later prehistoric periods, such as the Chalcolithic and Iron Age of the Levant, and even in later historical periods (van den Brick, 2008).In Iran, there have been reports of similar bedrock features in the southern and central Zagros regions, which are believed to date back to the Epipalaeolithic Period (Conard and Ghasidian, 2011: 36, 40; Heydari-Guran, 2014: 228-229). Neolithic sites such as Chia Sabz and Teppeh Sarab Yavari have recorded bedrock mortars in their surroundings, but their dating is uncertain (Darabi, 1395; Alibaigi, 2013).Some scholars believe that, according to extensive research on the bedrock features of the Levant, during the early Neolithic period, activities such as grounding and pounding started taking place in residential areas. This could indicate a practical division of tasks, with noisy and messy activities being done in open public spaces, while the final stages of processing were carried out in enclosed spaces (Belfer-Cohen and Hovers, 2005: 303).

Ground stone assemblages, including portable and bedrock features, were crucial in the Neolithization process in Western Asia. The increasing sedentism observed during the Natufian period is often considered a significant factor in the development of ground stone tools. These tools, particularly the larger ones, may have served as fixtures within specific sites. Their presence, designs, and on site may have varied depending on the level of pre-planning and anticipation of site re-occupations. The different shapes of bedrock features near caves and rock shelters in Izeh Plain align with the relative dating of these archaeological sites. This dating suggests that the region experienced a high level of settlement during the late Paleolithic and early Neolithic periods. These features likely played a significant role in the semi-sedentary lifestyle of the last hunter-gatherers. They were also likely used during the beginning of the Neolithic Period and in later occupations of the Izeh Plain.