Paleoecological perspectives on human adaptation in central Panama. II the Holocene

A 17.5 m sedimentary core from Lake La Yeguada, central Panama provides the first complete Holocene sequence for the Pacific watershed of Lower Central America. Phytolith, pollen, and charcoal records document a long lowland history of foraging and food production. Human modification of tropical forests can be described as systematic during the early Holocene and was possibly associated with small-scale (garden?) horticulture involving native tubers. The incorporation of seed crops like maize and development of slash and burn techiques for larger-scale field systems is indicated by the increase of secondary forest taxa and removal of primary trees between 7000 and 4000 years ago. After this time, agricultural intensification in an essentially deforested landscape proceeded to the point where, by the time of Christ, agricultural abandonment of the lake watershed may have occurred as a result of loss of soil fertility. Events such as this in the interfluve forests may have, in part, precipitated the coalescence of population and settlement around the river valleys and the emergence of sedentary village life.     

Paleoecological perspectives on human adaptation in central Panama. I. The Pleistocene

Paleoecological data from two sites in central Pacific Panama have allowed the reconstruction of Late Pleistocene climate and vegetation in lowland areas, the timing of important environmental changes, and the generation of predictions concerning Paleoindian settlement and subsistence. The last 9000 years of the glacial period, from 20,000 B.P. until 11,050 B.P. were marked by climates cooler and drier than today's. The period from ca. 16,000 B.P. until 11,000 B.P. appears to have been the coolest and driest. We postulate that the major effects of these conditions were to have brought montane vegetation 900 m lower than its present range and to create tracts of open landscape along the Pacific coast. Forests, however, were widespread in extent and many lowland forest taxa apparently persisted, creating the basis for the rejection of refugial theory as an explanatory model for early human occupation. Neither the admittedly limited archaeological or paleoecological data indicated the presence of pre-Clovis populations in Panama, and we chose to view Clovis as the first human expression on the Isthmus. Correlation of reconstructed environmental setting with Paleoindian site location suggests that Clovis adaptations were fluid and flexible, and utilized a wide variety of vegetation types. Occupation and modification of tropical forest appear to have been integral parts of Clovis subsistence and settlement strategies.     

顾功叙

某车站,一队人员正在等待SEG(美国勘探地球物理工作者协会)的往返列车前往美国的阿纳海姆会谈中心。该队人员包括由中国学生组成的3名代表,1名展览人员,名义会员顾功叙以及他的夫人,另外还有1名SEG的职员。除此外,这里呈现的完全是普通公交车站的情形。开始的时候,大家好像达成     

The institutional foundations of economic performance of mussel production: The Spanish case of the Galician floating raft culture

This paper analyses the institutional foundations of the mussel production sector in Galicia, which is one of the leading producers in the world. After demonstrating the importance of the sector and presenting the theoretical framework and an historical introduction, the paper formulates an agenda of institutional analysis topics from a positive perspective. This agenda includes the problem of the common pool, the role of the State, the legal norms, the property rights system, the organisation of the sector, the rules and public policies and the status quo. This paper presents a case analysis dealing with the relationships between institutions and economic organisation, and furnishes evidence and relevant knowledge for the elaboration of comparative analysis in the economics of natural resources.     

New eucrite Dar al Gani 872: Petrography,chemical composition,and evolution

Abstract— Dar al Gani 872 (DaG 872) is a new meteorite from Libya that we classified by means of Instrumental Neutron Activation Analysis (INAA), electron microprobe, and optical microscopy. According to our results, DaG 872 is a Mg‐rich main group eucrite, i.e., a monomict noncumulate basaltic eucrite displaying a predominant coarse‐grained relict subophitic and a fine‐grained granulitic texture. The meteorite also shows pockets of late‐stage mesostasis and is penetrated by several calcite veins due to terrestrial weathering. Finally, it exhibits shock phenomena of stage 1–2 including heavily fractured mineral components, undulose extinction of plagioclase, kinked lamellae, and mosaicism in pyroxenes corresponding to peak pressures of ?20 GPa. In view of petrographic criteria as well as compositional and exsolution characteristics of its pyroxenes, the sample represents a metamorphic type 5 eucrite. Assuming the metamorphic type to be a function of burial depth on the parent body and taking into account the relatively high shock stage, the excavation of DaG 872 was likely induced by a major impact event. Prior to this point, DaG 872 apparently underwent a 4‐stage geological evolution that is reflected by intricate textural and mineralogical features.     

Evolution and classification of acapulcoites and lodranites from a chemical point of view

Abstract— We examined 15 bulk samples of the acapulcoite‐lodranite clan for their major, minor, and trace element concentrations using INAA techniques. Among the analyzed meteorites are 2 new acapulcoites (Dhofar [Dho] 290, Thiel Mountains [TIL] 99002) as well as an additional acapulcoite that has been described previously only in very brief form (Graves Nunataks [GRA] 98028). The petrographic attributes of these 3 samples are addressed thoroughly. We also include petrographic information on 2 acapulcoites from Africa: Northwest Africa (NWA) 725 and NWA 1058. In general, our study strongly supports the widely accepted idea that acapulcoites and lodranites evolved through partial melting and melt migration of metal/sulfide phases and plagioclase. Furthermore, we concur with previous researchers that the original bimodal classification scheme for acapulcoites and lodranites proves to be too simple. Based on our data set, we introduce an alternative, extended scheme. With respect to their elemental distribution patterns, we distinguish 5 subtypes comprising primitive, typical, transitional, and enriched acapulcoites on one hand and lodranites on the other. The chemical distinction between the primitive, typical, and transitional acapulcoites is rather subtle and gradual. It stands in contrast to the clear modifications observed for the signatures of the enriched acapulcoites and the lodranites. The definition of subcategories basically reflects the concentrations of 2 key elements: K and Se. We note, however, that the assignment of subgroups may not be exclusively inferred from elemental abundances but should also consider additional petrographic information.     

The Fountain Hills unique CB chondrite: Insights into thermal processes on the CB parent body

Abstract— We report the results of an extensive study of the Fountain Hills chondritic meteorite. This meteorite is closely related to the CB_a class. Mineral compositions and O‐isotopic ratios are indistinguishable from other members of this group. However, many features of Fountain Hills are distinct from the other CB chondrites. Fountain Hills contains 23 volume percent metal, significantly lower than other members of this class. In addition, Fountain Hills contains porphyritic chondrules, which are extremely rare in other CB_a chondrites. Fountain Hills does not appear to have experienced the extensive shock seen in other CB chondrites. The chondrule textures and lack of fine‐grained matrix suggests that Fountain Hills formed in a dust‐poor region of the early solar system by melting of solid precursors. Refractory siderophiles and lithophile elements are present in near‐CI abundances (within a factor of two, related to the enhancement of metal). Moderately volatile and highly volatile elements are significantly depleted in Fountain Hills. The abundances of refractory siderophile trace elements in metal grains are consistent with condensation from a gas that is reduced relative to solar composition and at relatively high pressures (10^?3bars). Fountain Hills experienced significant thermal metamorphism on its parent asteroid. Combining results from the chemical gradients in an isolated spinel grain with olivine‐spinel geothermometry suggests a peak temperature of metamorphism between 535 °C and 878 °C, similar to type‐4 ordinary chondrites.     

Hydrogeology of the Nurra Region, Sardinia (Italy): basement-cover influences on groundwater occurrence and hydrogeochemistry

The Nurra district in the Island of Sardinia (Italy) has a Palaeozoic basement and covers, consisting of Mesozoic carbonates, Cenozoic pyroclastic rocks and Quaternary, mainly clastic, sediments. The faulting and folding affecting the covers predominantly control the geomorphology. The morphology of the southern part is controlled by the Tertiary volcanic activity that generated a stack of pyroclastic flows. Geological structures and lithology exert the main control on recharge and groundwater circulation, as well as its availability and quality. The watershed divides do not fit the groundwater divide; the latter is conditioned by open folds and by faults. The Mesozoic folded carbonate sequences contain appreciable amounts of groundwater, particularly where structural lows are generated by synclines and normal faults. The regional groundwater flow has been defined. The investigated groundwater shows relatively high TDS and chloride concentrations which, along with other hydrogeochemical evidence, rules out sea-water intrusion as the cause of high salinity. The high chloride and sulphate concentrations can be related to deep hydrothermal circuits and to Triassic evaporites, respectively. The source water chemistry has been modified by various geochemical processes due to the groundwater–rock interaction, including ion exchange with hydrothermal minerals and clays, incongruent solution of dolomite, and sulphate reduction.     

Phytolith analysis of an archaeological site (longshan period) in Zhumadian City,Henan Province,China: Paleoenvironmental and cultural implications

With phytolith analysis of an archaeological site (Longshan Culture Period, 4800-4000 B. P.) in Zhumadian City of Henan Province, environmental and cultural information have been obtained. Phytolith assemblages both from the site and from a nearby ancient lake deposit of the same period indicate a warm and wet climate. Since this area is in an environment outside the natural distribution of wild rice, abundant “scooped” bilobate and special glume epidermal phytoliths found in all of the cultural layers and two samples of the lake deposits suggest that rice was cultivated in this region by the local people. © 1994 John Wiley & Sons, Inc.