Faunal changes in farming communities from Basketmaker II to Pueblo III (A.D. 1–1300) in the San Juan Basin of the American Southwest

The San Juan Basin of the American Southwest is home to some of the best known architecture in pre-Columbian North America. Although many faunal assemblages have been reported for individual sites, there has been little synthesis of hunting and husbandry in these farming communities. In an attempt to understand changing animal usage over time in the San Juan Basin, we use three indices to investigate the usage of artiodactyls, lagomorphs and turkeys. These three taxonomic groups formed the bulk of meat diets between Basketmaker II and Pueblo III times (A.D. 1–1300). Our analysis indicates that artiodactyls declined over time in relation to lagomorphs. Turkeys increased in the northern regions when compared to lagomorphs. Cottontails increased when compared to jackrabbits over time. We suggest that as human populations increased in the San Juan Basin, artiodactyls were more intensely hunted. People then began to raise more turkeys in favorable regions, and also hunted more lagomorphs in relation to artiodactyls. Deforestation, also as a result of increased human populations, would have created conditions more favorable for cottontails than jackrabbits in many areas.     

关于柴达木盆地自然生态变迁的人文考察

柴达木盆地自然生态环境十分脆弱,这种状况不但由其禀赋所决定,更与近50多年来人类在盆地开展的大规模生产活动不无关系。该时段的大部分时间,盆地内人与自然的关系基本上是对立的,从而在很大程度上导致了其自然生态环境更加脆弱并向恶化的方向持续变迁,已经严重威胁到该区域人类正常的生产生活。因此,在统筹柴达木盆地各种关系、构建和谐社会时,要更加重视其人与自然关系的和谐,以确保我国生态安全和资源安全。     

The Terminal Pleistocene/Early Holocene archaeology of the Great Basin

The archaeological record of the Terminal Pleistocene and Early Holocene in the Great Basin consists largely of surface lithic artifacts, and consequently research has concentrated on typological and technological studies. The small suite of radiocarbon dates available suggests human presence in the Great Basin by at least 11,500 B.P., but evidence of subsistence is scanty. Technological analyses as well as artifact distributions suggest that the earliest occupants of this region subsisted primarily by hunting, possibly large terrestrial game. As elsewhere in North America, the earliest occupants of the Great Basin faced a rapidly changing environment, with the drying of shallow pluvial lake remnants and the creation of new habitats. Paralleling these changes, significant subsistence resource diversification coupled with expansion into new environments is evident by the close of the Pleistocene.     

尼罗河流域文明与地理环境变迁研究

本文根据对尼罗河流域文明区地理环境变迁研究的结果,认为正是由于距今9000-4000年前亚非季风势力增强、季风雨量增加给尼罗河流域带来的湿润气候,为文明的形成和初步发展创造了优越的地理环境。因而尼罗河流域文明不仅仅是\"尼罗河的赠礼\",而应当更准确地说它是\"季风雨的赠礼\"。也正是由于季风雨的多寡在很大程度上制约着文明的盛衰,因此,由于从距今4000年前后开始的季风势力衰退和季风雨量锐减而导致的干旱化、沙漠化,则逐步吞噬了这一古老的文明。     

高质量发展视角下黄河流域城市网络的结构演变与影响因素研究

城市作为人口、产业等要素聚集地,基于多要素解构城市网络对明确城市高质量发展的内涵具有重要作用。本文通过修正经典引力模型和社会网络方法,分析了高质量视角下黄河流域城市网络结构演变特征,利用QAP方法探求其影响因素。结果表明：(1)黄河流域城市网络基本形成了以郑州、西安、济南、太原、兰州等省会城市为核心,辐射至周边城市的网络结构,网络密度逐渐增大但整体较低,网络通达度相对较高且稳定。(2)城市网络社群内部关联高于社群间关联,说明高质量发展视角下黄河流域城市网络社群溢出效应主要以社群内溢出为主,社群外溢作用较少。(3)区位条件、交通基础设施、产业结构、政府支持强度、科技创新的差异对黄河流域高质量发展的城市网络演变有显著影响。     

Emwadea microcarpa gen. et sp. nov.—anatomically preserved araucarian seed cones from the Winton Formation (late Albian), western Queensland,Australia

Dettmann, M.E., Clifford, H.T., Peters, M., June 2012. Emwadea microcarpa gen. et sp. nov.—anatomically preserved araucarian seed cones from the Winton Formation (late Albian), western Queensland, Australia. Alcheringa, 217–237. ISSN 0311-5518.

A new genus and species, Emwadea microcarpa Dettmann, Clifford & Peters, is established for ovulate/seed cones with helically arranged cone scales bearing a centrally positioned, inverted ovule from the basal Winton Formation (late Albian), Eromanga Basin, Queensland. The cones are small, prolate ellipsoidal (9.5–14 mm vertical axis, 6.3–8.7 mm transverse axis) with wedge-shaped cone scales bearing winged seeds attached adaxially to the scale only by tissues surrounding the vasculature entering the ovule. Ovuliferous tissue that is free from the cone scale extends distally from the chalaza; the seeds' lateral wings are derived from the integument. Foliage attached to the cones is spirally arranged, imbricate and with spreading and incurved bifacial blades with acute tips; stomata are arranged in longitudinal files and are confined to the adaxial surface. The cone organization testifies to placement within the Araucariaceae, and is morphologically more similar to Wollemia and Agathis than to Araucaria.

Mary Dettmann [mary.dettmann@qm.qld.gov.au] and Trevor Clifford, Queensland Museum, PO Box 3300, South Brisbane, Q 4101, Australia; Mark Peters, PO Box 366 Gumeracha, SA 5233, Australia. Received 31.3.2011; revised 23.8.2011; accepted 5.9.2011.

     

Abnormally pressured beds as barriers to diffusive solute transport in sedimentary basins

Diffusion can drive significant solute transport over millions of years, but ancient brines and large salinity gradients are still observed in deep sedimentary basins. Fluid flow within abnormally pressured beds may prevent diffusive transfer over geologically significant periods, if the abnormally pressured bed is surrounded by normally pressured beds. Analytic solutions based on sediment loading and unloading demonstrate that this effect should be considered in beds with a compressibility exceeding 10^?8 Pa^?1, with a thickness of 100 m or more, or a sedimentation rate exceeding 10^?5 m year^?1. Conditions favourable for our model of abnormally pressured beds appear common in sedimentary basins. Large salinity gradients associated with clay beds have previously been attributed to membrane effects, but flow patterns associated with abnormally pressured beds appear more robust in the presence of heterogeneity and discontinuities than membrane effects. Calculations suggest that thick underpressured shales in the Alberta basin may have allowed ancient evaporatively concentrated brines to be preserved beneath a vigorous topography‐driven flow system over the last 60 My. In the Illinois basin, drained overpressured beds may have limited solute transport across the New Albany shale until approximately 250 Ma. It is unlikely, however, that overpressures could have persisted long enough to explain concentration gradients observed in the modern basin. These gradients may instead reflect relatively recent halite dissolution above the New Albany shale.     

论典型河谷盆地型城市兰州的发展模式

本文从兰州的自然条件、政治、军事、交通、经济贸易、工业化等角度讨论了兰州城市的兴起与发展模式,分析了这个河谷盆地型城市的空间结构模式,阐述了河谷盆地型在城市建设与发展过程中应特别注意的城市环境与土地以及自然灾害等关键性问题。