Analysis of Winter and Summer Glacier Mass Balances

Seasonal mass balance components b_w (winter balance) and b_s (summer balance) as well as c_t (total accumulation) and a_t (total ablation), can be used directly to infer climate variables. In contrast, a_c (net balance of the accumulation area) and a_a (net balance of the ablation area), and b_a or b_n (annual or net balance) can not. The traditional Alpine system of observations of a_c and a_a , however, can be converted to true seasonal values b_w and b_s if both pairs of components are simultaneously observed for some years, because a correlation between the two pairs of components exists. We analyzed b_w and b_s data and their mean, standard deviations and ratios of these to the corresponding net or annual balances for 50 glaciers with relatively long records representing different regions in the northern hemisphere. We also investigated correlations between seasonal components. A negative correlation between b_w and b_s exists at many glaciers. About two-thirds of the glaciers show insignificant correlations (?0.3 < r < 0.3), implying independence of summer and winter balances. In a few unusual cases the correlations are positive. These different correlations, or lack thereof, may offer insight into feedback conditions that must exist in this climate-related system. The correspondence of the b_w and c_t , and b_s and a_t , appears to depend largely on the relative amounts of summer snowfall, a function of their climatic environment expressed as [α = (b_w+b_s)/2]. The contribution of variability of b_s to the net balance increases markedly with decreasing values of α. The variability of b_w and b_s , and therefore the net balance, has been increasing with time; whether this is due to an increase in climate variability or to other causes is not clear. It appears that b_w has been increasing with time at the highest altitudes, but b_s has been increasing more rapidly especially at low altitudes; the many-glacier average net balance is becoming more negative.     

THESES TITLES

The Arctic Bibliography

Struggle for Africa

English Topographic Terms in Florida, 1563–1874

Culture Worlds

Economic Statistics of Texas 1900–1952

Water Requirements Survey, Red River Basin, Texas

Geography from the Air

The Columbus Atlas

Map of Caribbean Oil

Oil in the Soviet Union

Goode's World Atlas

Regional Atlas

World Resource Statistics     

Herbaceous layer development during spring does not deplete soil nitrogen in the Portuguese montado

Nitrogen (N) content in the soil and in the herbaceous biomass were monitored during spring of 2004-2006 to determine how the herbaceous layer development influences soil N availability in the montado ecosystem of southern Portugal. Highest (246.6 ± 52.7 g m⁻²) and lowest (123.2 ± 89.5 g m⁻²) peak biomass occurred in 2006 and 2005 respectively. Total soil N within the top 20 cm soil profile ranged between 0.2 ± 0.1% in February and 0.41 ± 0.2% in May, while available soil N was lowest (5 ± 2 μg g⁻¹soil) in February but increased three-to-five fold in March and was >17.5 μg g⁻¹soil at senescence in May. Significant (p < 0.001) increase in total N in the aboveground pool occurred between February and May. There was however, no decay in soil N content. Instead, the herbaceous vegetation enhanced soil N input and N retention in the ecosystem. Most of the herbaceous plants were annuals with large reserves of organic N at senescence, which returned to the soil as detritus. The herbaceous vegetation is a critical component of the montado that contributes to N recharge and cycling within the ecosystem.     

Sand transport under increased lateral jetting of raindrops induced by wind

Wind tunnel experiments for ‘Raindrop Detachment and Wind-Driven Transport’ (RD–WDT) process were conducted under improved lateral jetting induced by wind velocities of 6.4, 10, and 12 m s^− 1 at nozzle operating pressures of 75, 100, and 150 kPa. Wind-driven rainfalls were also incident on the windward and leeward slopes of 4° and 9° to have a broad variation in the angle of incidence. The objective of this experimental set-up was to distinguish the roles of both impact components of obliquely striking wind-driven raindrops on RD and wind on WDT. Raindrop impact components and reference horizontal wind were quantified by normal (E_tz) and horizontal (E_tx) kinetic energy fluxes and wind shear velocity (u), respectively, to physically model the process of RD–WDT. The results showed, at each level of u, differential sand transport rates by RD–WDT (q_m(RD–WDT)) occurred depending on the magnitude of raindrop impact components, and q_m(RD–WDT) increased as the relative contribution of E_tz increased. Although E_tx was more correlated with q_m(RD–WDT) than E_tz, the extreme increases in E_tx at the expense of E_tz brought about no increases but decreases in q_m(RD–WDT). An RD–WDT model was built under the process of examining the discrete effects of E_tz and E_tx on RD together with u and resulted in a better coefficient of determination (R² = 0.89) than only total kinetic energy (E_t) did alone with u (R² = 0.84). In this study, E_tx was strongly related to u and not to E_tz, which was the principal difference from the previous rainsplash studies, which relied on the compensatory lateral jet development by the compressive pressure build-up at the raindrop–soil interface. Including E_tx in the RD–WDT model both separated the distinct role of each raindrop impact component in RD and improved the performance of u in WDT by better distinguishing its interaction with E_tx, which was not explicitly separated in previous models of RD–WDT.     

Biogeochemical records of paleoenvironmental changes in Nainital Lake,Kumaun Himalayas,India

Rapid urbanization and increased tourism around Nainital Lake in the Kumaun Himalayan region in north India has raised concerns about sediment and water pollution. Lead-210 dated sediment cores from the lake represent ~95 years of accumulation and yield a mean sedimentation rate of ~4.7 mm year⁻¹. Total organic carbon (TOC), percent N and S and their atomic C/N and C/S ratios, stable isotopes (δ¹³C, δ¹⁵N, and δ³⁴S), and specific biomarkers (n-alkanes and pigments) were measured in the core. Organic matter is primarily derived from in-lake algal production and TOC flux varies from 1.0 to 3.5 g m⁻² year⁻¹. Sediments are anoxic (Eh −328 to −187 mV) and have low (0.10–0.30 g m⁻² year⁻¹) N, but high (0.37–1.0 g m⁻² year⁻¹) S flux. Shifts in δ¹³C, δ¹⁵N, and δ³⁴S suggest in-lake microbial processes dominated by denitrification and sulfate reduction. The sediments are dominated by short-chain hydrocarbons with low Carbon Preference Index values. The pigments indicate a gradual shift to cyanobacterial domination of the phytoplankton community in recent years. Despite an increase in external input of nutrients, the trophic state of the lake has remained largely unchanged, and the perceived human-induced impacts are limited.     

Geochemistry of waters and brines from the Salinas Grandes basin,Córdoba,Argentina. I. Geomorphology and hydrochemical characteristics

This paper reports on hydrochemical features of diluted waters in the source areas and the brine end-members dominant in the playa of the Salinas Grandes Basin, Córdoba, Argentina. Special emphasis was placed on the study of the relationship between geomorphology and the resulting hydrochemical fractionation. Inflow is from springs and mountain streams which disappear before reaching the saline complex. The playa and intermittent saline lakes are mainly fed by groundwater flow and a few moderately saline and perennial springs. Conversely, ephemeral lakes are fed by atmospheric precipitation and groundwater, whereas small ponds are only fed by atmospheric precipitation. The absence of a clear linkage between geomorphological units and water types was evident in the source areas. Up to four types of water were recognized in a given geomorphological unit. From the sandflat downward towards the playa, the correspondence between geomorphological units and water types was clear, coinciding with a decreased hydrochemical heterogeneity. In this subenvironment, I have recognized two dominant types of water (SO ₄ ^2– –Cl^––HCO ₃ ^– –Na⁺ and Cl^––SO ₄ ^2– –HCO ₃ ^– –Na⁺), which can be considered the original members of the neutral brine in the playa (Cl^––SO ₄ ^2– –Na⁺ where Ca²⁺+Mg²⁺ do not surpass 5 meq per cent), and an intermediate type in the mudflat (Cl^––SO ₄ ^2– –Na⁺ where the contribution of Ca²⁺+Mg²⁺ reaches up to 15 meq per cent). It seems evident that in the zone between the source areas and the sandflat, hydrochemistry is governed by chemical weathering. In stream floodplains and in the distal alluvial plain, close to the saline complex, the increase in water types as well as the increase of HCO ₃ ^– with respect to SO ₄ ^2– , were explained by the mixture of aquifers controlled by the Salinas Grandes-Salinas de Ambargasta fracture. In the saline complex, the more concentrated end-members are the result of evaporation of the two more frequent water-types in the sandflat subenvironment, and salt dissolution of ancient evaporite deposit.     

1960-2007年中国地表潜在蒸散发敏感性的时空变化(英文)

Potential evapotranspiration (E0), as an estimate of the evaporative demand of the atmosphere, has been widely studied in the fields of irrigation management, crop water demand and predictions in ungauged basins (PUBs). Analysis of the sensitivity of E0 to meteorological factors is a basic research on the impact of climate change on water resources, and also is important to the optimal allocation of agricultural water resources. This paper dealt with sensitivity of E0 over China, which was divided into ten drainage systems, including Songhua River basin, Liaohe River basin, Haihe River basin, Yellow River basin, Yangtze River basin, Pearl River basin, Huaihe River drainage system, Southeast river drainage system, Northwest river drainage system and Southwest river drainage system. In addition, the calculation method of global radiation in Penman-Monteith formula was improved by optimization, and the sensitivities of Penman-Monteith potential evapotranspiration to the daily maximum temperature (STmax), daily minimum temperature (STmin), wind speed (SU2), global radiation (SRs) and vapor pressure (SVP) were calculated and analyzed based on the long-term meteorological data from 653 meteorological stations in China during the period 1960-2007. Results show that: (1) the correlation coefficient between E0 and pan evaporation increased from 0.61 to 0.75. E0 had the decline trends in eight of ten drainage systems in China, which indicates that "pan evaporation paradox" commonly exists in China from 1960 to 2007. (2) Spatially, Tmax was the most sensitive factor in Haihe River basin, Yellow River basin, Huaihe River drainage system, Yangtze River basin, Pearl River basin and Southeast river drainage system, and VP was the most sensitive factor in Songhua River Basin, Liaohe River basin, Northwest river drainage system while Rs was the most sensitive factor in Southwest river drainage system. For the nation-wide average, the most sensitive factor was VP, followed by Tmax, Rs, U2 and Tmin. In addition, the changes in sensitivity coefficients had a certain correlation with elevation. (3) Temporally, the maximum values of STmax and SRs occurred in July, while the maximum values of STmin, SVP and SU2 occurred in January. Moreover, trend analysis indicates that STmax had decline trends, while STmin, SU2, SRs and SVP had increasing trends.     

Nitrogen deposition effects on tissue chemistry and phosphatase activity in Cladonia foliacea (Huds.) Willd., a common terricolous lichen of semi-arid Mediterranean shrublands

In this article we evaluate the potential use of Cladonia foliacea tissue N content, C:N ratio, and phosphomonoesterase (PME) activity as biomarkers of N deposition by means of a field experiment. In order to do this, we continuously added NH₄NO₃ to a semi-arid shrubland at four rates: 0, 10, 20 and 50 kg N ha⁻¹ yr⁻¹ starting in October 2007. Tissue N content and C:N ratios, considered as N stress indicators, significantly increased and decreased, respectively, after 1.5 years. The response found suggests N saturation above 20 kg N ha⁻¹ yr⁻¹. After 2.5 years, extracellular PME activity increased with 20 kg N ha⁻¹ yr⁻¹ and this was attributed to an induced nutritional (N to P) imbalance. Above this threshold, PME significantly decreased as a consequence of the physiological stress caused by extra N. Effects on PME were dependent on the soil properties (pH and Ca and Mg availability) experienced by C. foliacea. PME response suggests a critical load of ∼26.4 kg N ha⁻¹ yr⁻¹ (20 kg N ha⁻¹ yr⁻¹ + background) for this lichen. Further tissue chemistry and PME evaluations in C. foliacea and soil surveys conducted along wide N deposition gradients will confirm the potential use of this species as a biomonitor of N pollution and the importance of soil properties on its ability to respond to atmospheric reactive N.     

Tree biomass and soil organic carbon densities across the Sudanese woodland savannah: A regional carbon sequestration study

Mean tree biomass and soil carbon (C) densities for 39 map sheet grids (1° lat. × 1.5° long.) covering the Acacia woodland savannah region of Sudan (10–16° N; 21–36° E) are presented. Data from the National Forest Inventory of Sudan, Harmonized World Soil Database and FAO Local Climate Estimator were used to calculate C densities, mean annual precipitation (MAP) and mean annual temperature (MAT). Above-ground biomass C and soil organic carbon (SOC, 1 m) densities averaged 112 and 5453 g C m⁻², respectively. Below-ground biomass C densities, estimated using root shoot ratios, averaged 33 g C m⁻². Biomass C densities and MAP increased southwards across the region while SOC densities were lowest in the centre of the region and increased westwards and eastwards. Both above-ground biomass C and SOC densities were significantly (p < 0.05) correlated with MAP (r_s = 0.84 and r_s = 0.34, respectively) but showed non-significant correlations with MAT (r_s = −0.22 and r_s = 0.24, respectively). SOC densities were significantly correlated with biomass C densities (r_s = 0.34). The results indicated substantial under stocking of trees and depletion of SOC, and potential for C sequestration. Up-to-date regional and integrated soil and forest inventories are required for planning improved land-use management and restoration.     

长江口潮滩沉积物－水界面无机氮交换通量

对长江口滨岸潮滩7个典型断面三态氮的界面交换通量进行了三年多的季节性连续观测,结果表明无机氮的界面交换行为存在复杂的空间分异和季节变化。NO^-₃-N和NH⁺₄-N的界面交换通量正负变化范围较大,分别介于-32.82~24.13 mmol.m^-2.d^-1和-18.45~10.65mmol.m^-2.d^-1之间;而NOsup>-₂-N的界面交换通量很小,仅为-1.15~2.82 mmol.m^-2.d^-1。NO^-₃-N的界面交换具有明显的上下游季节性时空分异特征,而NH⁺₄-N的界面交换则表现为南北岸季节性时空分异现象。盐度是控制长江口滨岸潮滩NH⁺₄-N界面交换行为的主要因素,而沉积物粒度、水体 NO^-₃-N浓度、沉积物有机质含量、水温和溶解氧含量则以不同的组合方式,共同制约着 NO^-₃-N在潮滩界面交换的时空分异格局。     

Growth response of three globose cacti to radiation and soil moisture: An experimental test of the mechanism behind the nurse effect

Cactus seedlings often establish under nurse plants which modify environmental conditions by increasing moisture and decreasing solar radiation, which may cause beneficial and detrimental effects, respectively, on seedling growth. Three soil moisture treatments (5%, 25% and 60%) and two solar radiation levels (100% exposure=243 μmol m⁻² s⁻¹, and 40%=102 μmol m⁻² s⁻¹) were used in a factorial design to analyze seedling growth response of three rare cactus species (Mammillaria pectinifera, Obregonia denegrii and Coryphantha werdermannii). The variables evaluated were relative growth rate (RGR), root/shoot ratio (R/S), and K (RGR_roots/RGR_shoot), obtained from an initial seedling harvest (6-month-old seedlings) and a final harvest 6 months after treatment application. All three species had slow RGRs (0.002–0.012 g g⁻¹ day⁻¹). O. denegrii had the lowest RGR values, but was the only species for which R/S and K varied with soil moisture. While all seedlings responded markedly to soil moisture, no response was observed to radiation treatments. The latter might have been related to the relatively low solar radiation levels present in the greenhouse. Yet, our results suggest that the main benefit nurse plants offer to seedlings is the increase in soil moisture.     

四元体系Li2SO4+Na2SO4+K2SO4+H2O298.2 K相平衡研究

为了获取锂钠钾共存硫酸盐体系298.2 K下各盐结晶形式,采用等温溶解平衡法研究了298.2 K下四元体系Li₂SO₄₊Na₂SO₄₊K₂SO₄₊H₂O的相平衡关系,测定了该体系的溶解度和密度,采用X-ray粉晶衍射法测定了平衡固相组成,并绘制了相应的稳定相图和多温对比图。研究表明,298.2 K下该四元体系为复杂四元体系,有复盐2Li₂SO₄·Na₂SO₄·K₂SO₄、Li₂SO₄·3Na₂SO₄·12H₂O、LiKSO₄、Na₂SO₄·3K₂SO₄生成。其稳定相图由6个四元共饱点、12条单变量曲线以及7个结晶区组成。其中,复盐Na₂SO₄·3K₂SO₄结晶区最大,表明其在该体系中最易结晶析出;Li₂SO₄·H₂O结晶区最小。对比273.2 K、288.2 K、298.2 K、323.2 K、373.2 K四元体系多温相图可知,273.2 K时未发现复盐Na₂SO₄·3K₂SO₄和2Li₂SO₄·Na₂SO₄·K₂SO₄结晶形式;Na₂SO₄·10H₂O和Li₂SO₄·3Na₂SO₄·12H₂O结晶形式在323.2 K和373.2 K时转变为Na₂SO₄和Li₂SO₄·Na₂SO₄。288.2~373.2 K时随温度升高,K₂SO₄和Na₂SO₄·10H₂O结晶相区减小,Li₂SO₄·H₂O、Na₂SO₄、LiKSO₄和Li₂SO₄·Na₂SO₄结晶相区增大;Na₂SO₄·3K₂SO₄结晶相区先增大后减小,在298.2 K时结晶相区最大;2Li₂SO₄·Na₂SO₄·K₂SO₄结晶相区先减小后增大,298.2 K时结晶相区最小。     

<Emphasis Type="Italic">Bosmina</Emphasis> remains in lake sediment as indicators of zooplankton community composition

We measured Bosmina spp. mucro and antennule lengths in surface sediment samples from Wisconsin lakes to test whether such measures could be used to reconstruct zooplankton community composition and size structure in paleolimnological studies. Our data set included 58 lakes of various depths, water chemistry, trophic state, macrophyte cover, and zooplankton community composition. We used non-metric multidimensional scaling ordination (NMS) and simple correlation analysis to assess whether mucro and antennule measurements reflect the zooplankton community size structure. Bosmina mucro length (r = 0.727, p < 0.05) and antennule length (r = 0.360, p < 0.05) correlated with the NMS axis, which essentially represents zooplankton community size structure. Bosmina mucro length correlated positively with the abundance of the large-bodied zooplankter Epischura lacustris (r = 0.364, p < 0.01), as well as Diacyclops thomasi (r = 0.256, p < 0.05), and Leptodiaptomus minutus (r = 0.578, p ≤ 0.001), but correlated negatively with the abundance of the small-bodied zooplankter Tropocyclops prasinus (r = −0.385, p < 0.01). Bosmina antennule length correlated positively with the abundance of L. minutus (r = 0.344, p < 0.01) and negatively with T. prasinus (r = −0.258, p < 0.05). This broad, spatial scale assessment supports the use of Bosmina mucro and antennule lengths as a proxy for zooplankton community size structure. Mucro length is a stronger indicator of zooplankton community size structure as seen in its strong correlation with the NMS axis 1 and the significant correlations with abundance of predatory copepods.     

Capacity for water conservation in invasive (Gerbillus nigeriae) and declining rodents (Taterillus pygargus and Taterillus gracilis) that exhibit climate-induced distribution changes in Senegal

Following the southward shift of rainfall isolines in the Sahel at the end of the 1960s, Gerbillus nigeriae appeared in northern Senegal in the mid-1990s, and two resident Gerbillidae (Taterillus pygargus and Taterillus gracilis) subsequently declined. We investigated the causal role of the capacity to conserve water in such climate-related shifts in the distribution of these Gerbillidae by comparing the effects of a water-poor diet on the water-efflux rate (W_−out) of freshly trapped adults pre-acclimatized to a water-rich diet. During the 12-day period of water restriction in all species, 30-50% of individuals became hyperactive and showed greater weight loss and higher W_−out than the remaining inactive individuals. Such emergence of migratory strategists within populations could accelerate the expansion of G. nigeriae. On a water-poor diet, T. gracilis showed a lower capacity to conserve water (higher W_−out) than T. pygargus and G. nigeriae, in both inactive (W_−out = 44.5 ± 1.8 vs 29.6 ± 0.8 vs 27.4 ± 0.7 ml kg^−0.82.day⁻¹, respectively) and hyperactive individuals (W_−out = 60.4 ± 1 vs 45.4 ± 0.7 vs 44 ± 0.8 ml kg^−0.82.day⁻¹, respectively). We propose that the capacity to conserve water accounted for both expansion of G. nigeriae and decline of T. gracilis, whereas competition between T. pygargus and G. nigeriae could account for the decline of T. pygargus.     

Plant productivity, predation, and the abundance of black-tailed jackrabbits in the Chihuahuan Desert of Mexico

The abundance of black-tailed jackrabbits (Lepus californicus) can fluctuate dramatically. We used data from the Chihuahuan Desert to test the relative strength of top-down (predation) or bottom-up (food availability) limiting forces. Predictions for the top-down hypothesis were, 1) a positive relationship between coyote (Canis latrans) and jackrabbit abundance (numerical response) and 2) a positive relationship between percent occurrence of jackrabbits in coyote scats and jackrabbit abundance (functional response). Predictions for the bottom-up hypothesis were, 1) plant productivity is directly related to precipitation, 2) jackrabbit abundance is positively related to precipitation and plant productivity, and 3) changes in abundance of jackrabbits over the reproductive season will be directly related to precipitation and plant productivity. We found a limited numerical response but no functional response of coyotes to jackrabbit abundance. Forb productivity was significantly related to annual precipitation levels (r² = 0.69, p = 0.002). Grass productivity was related to annual precipitation (r² = 0.34, p = 0.028). Jackrabbit abundance (r² = 0.38, p = 0.002) and changes in abundance (r² = 0.73, p < 0.001) were significantly related to precipitation and forb and grass productivity. We conclude that precipitation levels and plant productivity affect jackrabbit abundance more than predation levels.     

The effect of biological soil crusts of different successional stages and conditions on the germination of seeds of three desert plants

Biological soil crusts greatly affect soil surface properties, which, in turn, may alter seed germination of vascular plants. We investigated the effects of two types of biological soil crusts (moss crust and algal crust) at different ages on the seed germination of Bassia dasyphylla and Artemisia ordosica. We also investigated the effects of crust conditions (living crust and dead crust) on seed germination of B. dasyphylla, A. ordosica and Eragrostis poaeoides. The presence of both algal and moss crusts significantly enhanced the germination of B. dasyphylla and A. ordosica compared with uncrusted soil. Crust age had no significant effect on the germination of either B. dasyphylla or A. ordosica for both moss and algal crusts. Germination of B. dasyphylla differed significantly between moss and algal crusts, but germination of both A. ordosica and E. poaeoides did not. Germination of A. ordosica, E. poaeoides and B. dasyphylla was significantly higher on living algal crust than on dead crust and uncrusted soil, while living moss crust enhanced the germination of both A. ordosica and B. dasyphylla but had no significant effect on E. poaeoides.     

Chemical weathering and CO2 consumption in the Xijiang River basin, South China

Monthly samples of riverine water were collected and analyzed for the concentrations of major ions (Ca²⁺, Mg²⁺, K⁺, Na⁺, HCO₃⁻, SO₄²⁻, Cl⁻, NO₃⁻), dissolved silicon, and total dissolved solids (TDS) at Wuzhou hydrological station located between the middle and lower reaches of the Xijiang River (XJR) from March 2005 to April 2006. More frequent sampling and analysis were carried out during the catastrophic flooding in June 2005. Stoichiometric analysis was applied for tracing sources of major ions and estimating CO₂ consumption from the chemical weathering of rocks. The results demonstrate that the chemical weathering of carbonate and silicate rocks within the drainage basin is the main source of the dissolved chemical substances in the XJR. Some 81.20% of the riverine cations originated from the chemical weathering processes induced by carbonic acid, 11.32% by sulfuric acid, and the other 7.48% from the dissolution of gypsum and precipitates of sea salts within the drainage basin. The CO₂ flux consumed by the rock chemical weathering within the XJR basin is 2.37 × 10¹¹ mol y^− 1, of which 0.64 × 10¹¹ mol y^− 1 results from silicate rock chemical weathering, and 1.73 × 10¹¹ mol y^− 1 results from carbonate rock chemical weathering. The CO₂ consumption comprises 0.38 × 10¹¹ mol during the 9-d catastrophic flooding. The CO₂ consumption from rock chemical weathering in humid subtropical zones regulates atmospheric CO₂ level and constitutes a significant part of the global carbon budget. The carbon sink potential of rock chemical weathering processes in the humid subtropical zones deserves extra attention.     

SUGGESTIONS FROM THE AAG PLACEMENT COMMITTEE

Perspective on the Nature of Geography. Richard Hartshorne

The Statesman's Year-Book 1959. Ed. S. H. Steinberg

Microclimatic and Vegetational Studies in a Cold-Wet Deciduous Forest. Philip Ross

Urban Problems and Techniques, Ed. Perry L. Norton

Statistisk Sentralbyra, Bosettningkart over Norge (Settlement Map of Norway

Mapa General de Cuba. Edited by P. Fernandez y Cia

Water for the Future. John R. Stockton, Stanley A. Arbingast, Richard C. Henshaw, Jr., and Alfred G. Dale

America's Natural Resources. Ed. Charles H. Callison

Everydav Meteorology. A. Austin Miller &; M. Parry

Geography of the Soviet Union: Electric Power

Thailand–An Outline. Edwin F. Stanton

Historical Atlas and Gazetteer. A Study of History, Volume XI. Arnold J. Toynbee &; Edward D . Myers

New Viewpoints in Geography. Preston E. James, Ed.

Man In Malaya. B. W. Holler

The Location of the Synthetic-fiber Industry, A Case Study in Regional Analysis. Joseph Airov

General Meteorology. 3rd Ed. Horace R. Byers

Man's Journey Through Time. L. S. Palmer

Anglo-America: A Regional Geography. Earl B. Shaw

Proceedings of IGU Regional Conference in Japan 1957.     

Considerations on the chronological and causal relationships between talus flatirons and palaeoclimatic changes in central and northeastern Spain

Talus flatirons are relatively common landforms in arid and semiarid areas. They are frequent in the Duero, Tajo and Ebro Tertiary Basins in Spain. The generation of a flatiron requires the alternation of periods with a prevalence of accumulation processes followed by periods with a preponderance of erosion processes. In the three Tertiary basins considered here talus flatirons have been found in numerous places and up to five stages of slope evolution have been recognised in some locations. The second youngest stage (S₂) has been dated in several places in the Ebro and Duero Basins through ¹⁴C. The age of this stage ranges from 2529 ± 52 to 3590 ± 40 ¹⁴C yBP. The third youngest stage (S₃) has yielded dates of 27,862 ± 444 radiocarbon years BP in the Ebro Basin, and 28,550 ± 130 ¹⁴C yBP in the Duero Basin. S₄ has been dated in the Ebro Basin to 35,570 ± 490 ¹⁴C yBP. The S₂ slope facets correspond to the Iron and Bronze Age Cold Stages. The S₃ and S₄ flatirons may be correlated with the Heinrich events H₃ and H₄. These dates may indicate that the accumulation periods on the slopes correspond to cold global events. The dates obtained for the stages S₃ and S₄ in the central and northeastern sectors of Spain and their good correlation with Heinrich events suggest that flatirons could be related to climatic sequences in the Upper Pleistocene and Holocene.