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931.
The factors which create crop marks at two archaeological sites, at Glenlochar, Kirkcudbrightshire and at Fisherwick, Staffordshire, are examined in some detail. Marks are best recorded at these places in cereals and show earliest over the shallowest soils. They appear when the potential soil moisture deficit, which occurs when water transpired by a crop exceeds rainfall, is greater than the amount of water in the soil available to the plant. Marks only show in grassland when the deficit is about 40 mm more than that calculated for cereals. Marks also appear in very wet years, but are fainter than those caused by a moisture deficit, and are probably caused by waterlogging in the soil. At both sites the soils are moderately stony and shallow over terrace sands and gravels, except for soils in infilled ditches over which crop growth is better.  相似文献   
932.
China is one of the few centers in the world where plant domestication evolved independently, but its developmental trajectory is poorly understood. This is because there is considerably less data from the terminal Pleistocene and early Holocene documented in China than in other regions, such as the Near East and Mesoamerica, and previous studies on Paleolithic subsistence in China have largely focused on animal hunting rather than plant gathering. To resolve these problems the current research investigated the range of plants used by late Paleolithic hunter–gatherers in the middle Yellow River region where some of the earliest farmers emerged. We employed usewear and starch analyses on grinding stones to recover evidence for plant use in a hunting–gathering population at a late Paleolithic site, Shizitan Locality 9 in Jixian, Shanxi (ca. 13,800–8500 cal. BP). The usewear analysis shows that all artifacts preserved a range of usewear patterns best matching multiple tasks and indicating multi-functional use. Starch remains recovered from these tools indicate that the Shizitan people collected and processed many types of grass seeds (Panicoideae and Pooideae subfamilies), acorns (Quercus sp.), beans (Phaseoleae tribe) and yams (Dioscorea sp.). The Shizitan people represented some of the last hunter–gatherers in the middle Yellow River region. Their broad spectrum subsistence strategy was apparently carried on by the first Neolithic farmers in the same region, who collected similar wild plants and eventually domesticated millets. The trajectory from intensified collection of a wide range of wild plants to domestication of a small number of species was a very long process in north China. This parallels the transition from the “broad spectrum revolution” to agriculture in the Near East.  相似文献   
933.
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