The stratigraphy and paleogeography of the Middle Paleolithic open-air site of 'Ein Qashish, Northern Israel

摘要

The Middle Paleolithic site of 'Ein Qashish is located on the floodplain of the Qishon stream, northern Israel, which drains into the Mediterranean Sea. It is located at the inlet to a narrow water gap between Mt. Carmel and Tiv'on Hills. The excavation and 3 trenches up to 5 m deep provide the stratigraphy and allow a reconstruction of the paleogeography and depositional environments. The archaeological layer, OSL dated to about 64 ± 4 ka, is composed of carbonate gravel and overlies 66 ± 4 ka (MIS4) black, heavy alluvial clays deposited by the Qishon Stream, which represents" marsh environment. The site is covered by another clay unit, representing a second marsh period between 50 ± 3 and 41 ± 3 ka (MIS3). This sedimentary complex is unconformably covered by coarse gravel and reddish clay matrix, dated to between 15.1 ± 0.7 and 10.5 ± 0.5 ka, which is derived from Wadi Qashish - a steep mountainous stream of Mt. Carmel. The mineralogical analyses of the clays indicate high quartz concentrations and smectitic IS, which support the interpretation of Qishon basin origin, versus illitic IS from Mt. Carmel slopes. The duration of the prehistoric human activity is estimated at ＜10 kyr, during which the Qishon stream transported fine clay by relatively low-magnitude flows over a relatively stable floodplain. The site is located over the toe of the gravelly alluvial fan of Wadi Qashish. During the end of the Pleistocene to the Holocene, the site was covered by coarse gravel from Mt. Carmel alternating with fine clay sed iments of the Qishon stream. Sea level during the occupation period was between 100 and 60 m b.s.l. and the coastline was located 10-7 km westward. The proposed mechanism for the marsh development is: (a) repeated episodes of blockage of the Qishon stream outlet at the narrow water gap by aeolian sand transported by westerly winds inland over the exposed continental shelf. The accumulation of sand and sandstone over the coastal plain during this period supports this idea. (b) Based on hydrological correlation with the Lake Lisan Levels the flows in the Qishon stream were low with large component of baseflows characterizing warmer and wetter periods that could not cut through the sand blockage and forced the water upstream into marshes. The marshes drained during the colder and drier Heinrich events H6/H5a and H4 which were characterized by higher frequency of large floods.