9 CHAPTER TWO GEOLOGY OF AN EARLY HOLOCENE SINKHOLE (NRQN), ISRAEL Amos Frumkin and Micka Ullman 2.1. INTRODUCTION Te PPNB (Pre-Pottery Neolithic B) site at Nesher-Ramla quarry is located in a natural sinkhole, 31.9150°N –34.9291°E, ~100 m asl, central Israel, ~21 km east of the Mediterranean coastline (Fig. 2.1). Tis sinkhole, dubbed NRQN (Nesher-Ramla Quarry Neolithic), is one of several sinkholes within the surrounding area (Frumkin et al. 2015). Sinkholes (dolines in the European literature) are characteristic karst landforms, ofen considered the diagnostic surface features of karst terrains (Waltham, Bell and Culshaw 2005; Kranjc 2013). Although most sinkholes in carbonate terrains are associated with epigenic karst (Ford and Williams 2007; Gutiérrez and Cooper 2013; Kranjc 2013), the clusters of sinkholes in the Nesher-Ramla area were formed over cavities generated by hypogene or ascending hydrothermal water (Frumkin and Gvirtzman 2006; Frumkin et al. 2015). Te global abundance of such voids has been noted in recent studies (Salvati and Sasowsky 2002; Bayari, Ozyurt and Pekkans 2009; Garašić 2000; Dublyansky 2013; Frumkin 2013; Klimchouk 2013; Palmer 2013; Klimchouk et al. 2017). Te area around the NRQN sinkhole comprises gently undulating chalk hills of the Senonian Menuha Formation, around 40 m thick. Tis bedrock is a part of the late Cretaceous carbonates deposited in an epicontinental sea on the northeastern edge of Gondwana. Te local Judean Lowland hills that are adjacent to Israel’s Coastal Plain are ofen covered with pedogenic limestone calcrete nari crust, or caliche, up to 2 m thick (Wieder, Sharabani and Singer 1993) (Fig. 2.2), overlain by alluvium and rendzina soil, with pockets of terra rossa and brown soils (vertisols) (Singer 2007). Te chalk is underlain by Turonian limestone of the Bina Formation. Te Nesher-Ramla cement factory has been quarrying the limestone and chalk since 1953. Te bottom of the quarry lies a few meters above the water table of Israel’s largest aquifer, Yarkon-Taninim. Its recharge zone extends along the western slopes of Israel’s central mountain ridge (Fig. 2.1a). Te aquifer discharges at the Yarkon and Taninim springs, north of Nesher-Ramla Quarry. Te aquifer rocks are predominantly Cenomanian-Turonian (late Cretaceous) carbonates interbedded with thin marl layers, with a total thickness of about 800 m. Most wells use the water of the “upper sub-aquifer,” consisting of late Cenomanian and Turonian rocks, while the Albian to lower Cenomanian “lower sub-aquifer,” has hardly been drilled, so its properties are less known. Te Yarkon-Taninim