Plateau West Research Articles

Optimization of floodwater redistribution from Lake Nasser could recharge Egypt’s aquifers and mitigate its excessive floods

Extreme precipitation periods, possibly related to climate change, over the Nile River source areas caused flooding in Sudan and excess runoff reaching Lake Nasser in Egypt in 1998–2002 and 2019–2022. Excess water from the 1st event (25.5 × 109 m3) was channeled to depressions within the plateau west of the Nile Valley, forming the Tushka Lakes, where it was left to evaporate, a fate that awaits the 53.5 × 109 m3 from the 2nd event while the underlying fossil Nubian Sandstone Aquifer System is being depleted (−0.98 × 109 m3/yr). We simulated release scenarios of excess Lake Nasser waters (53.5 × 109 m3) to proximal lowlands; preference was given to the scenario that recharged the aquifer through infiltration (74.3%) and minimized losses to evaporation (20.1%) and surface runoff (5.6%). Findings serve as an example of adaptations that replace catastrophic consequences of climate change with beneficial and sustainable development opportunities.

Glaciofluvial sequences recording the Birrfeld Glaciation (MIS 5d\u20132) in the Bern area, Swiss Plateau

In this paper, we document that glaciofluvial gravel sequences and glacial till deposits that are exposed in the Müntschemier and Finsterhennen gravel pits (Swiss Plateau west of Bern) record three glacial advances during the Birrfeld Glaciation, which corresponds to the last glacial cycle. Sedimentological logging shows that both gravel pits expose deposits of glaciofluvial braided river systems. These sediments are overlain by a till that was deposited during the Last Glacial Maximum (LGM). The results of the provenance analysis imply that the sediments were mainly supplied by the Valais Glacier, which originated in the Central Alps. A minor contribution of the material was supplied by the Saane Glacier with sources in the northern parts of the Alps. In addition, the morphometric analysis particularly of quartzite clasts in the till deposits indicate that while some clasts (the angular ones) were eroded and transported by the Valais Glacier from the Central Alps to the depositional site, the majority of the quartzite constituents (the rounded ones) were most likely reworked from the Molasse bedrock or older gravels. This implies that a large fraction of the sediments in the Müntschemier and Finsterhennen gravel pits could represent recycled material from older fluvial gravels and conglomerates that were then reworked by the glaciers as they advanced to the foreland. Based on the sedimentological data and considering published and new optically stimulated luminescence (OSL) chronological data, we propose a landscape evolution scenario where the first glacial advance occurred during Marine Isotope Stage (MIS) 5d. The second glacier advance followed during MIS 4, while the last one during the Last Glacial Maximum (LGM), which corresponds to the MIS 2. The MIS 5d advance is recorded by the lowest unit of the Müntschemier gravel pit and consists of a fining upward sequence made up of an alternation of gravel and sand beds. The MIS 4 advance is recorded by the unit beneath the LGM till at Müntschemier and by the lowermost layer in the Finsterhennen gravel pit. It comprises an alternation of gravel and sand beds, which coarsens and thickens upwards. The LGM advance, finally, resulted in the deposition of amalgamated gravel beds at Finsterhennen, which ended with the construction of a till that is encountered on the top of both gravel pits. Sediments related to the interstadial conditions between MIS 5a and MIS 5b and MIS 3 were not encountered, which suggests that the warmer periods were characterised by non-deposition and/or erosion, which possibly resulted in the observed sedimentary hiatus. Although the chronological results are still preliminary, the available information allows us to suggest that during the Birrfeld Glaciation, the Valais lobe advanced several times to the Swiss Plateau. In addition, the facies associations imply that the eastward expansion of the Valais lobe during the MIS 5d and MIS 4 were most likely shorter than during the LGM.

Spatiotemporal patterns and drivers of methane uptake across a climate transect in Inner Mongolia Steppe

Steppe soils are important biological sinks for atmospheric methane (CH4), but the strength of CH4 uptake remains uncertain due to large spatiotemporal variation and the lack of in situ measurements at regional scale. Here, we report the seasonal and spatial patterns of CH4 uptake across a 1200 km transect in arid and semi-arid steppe ecosystems in Inner Mongolia, ranging from meadow steppe in the east plain to typical and desert steppes on the west plateau. In general, seasonal patterns of CH4 uptake were site specific, with unimodal seasonal curves in meadow and typical steppes and a decreasing seasonal trend in desert steppe. Soil moisture was the dominant factor explaining the seasonal patterns of CH4 uptake, and CH4 uptake rate decreased with an increase in soil moisture. Across the transect, CH4 uptake showed a skewed unimodal spatial pattern, with the peak rate observed in the typical steppe sites and with generally higher uptake rates in the west plateau than in the east plain. Soil moisture, together with soil temperature, soil total carbon, and aboveground plant biomass, were the main drivers of the regional patterns of CH4 uptake rate. These findings are important for model development to more precisely estimate the soil CH4 sink capacity in arid and semi-arid regions.

The interaction of clonality, breeding system and genomics for a highly threatened plant species and the management implications

Clonal plants provide a challenge to ecological management and restoration programs. Clonal plants frequently occur as few genets over large spatial scales and may persist for hundreds of years. Hence population structures, effective population sizes and breeding systems of clonal plants are not well understood or managed at scales applicable to non-clonal species. This is a critical issue because clonality is a common trait including among threatened plants and more studies into the management requirements of clonal plant species are required. We investigate the impact of reducing the population size of a highly clonal species and how these impacts can be minimized.Persoonia hindiihas a restricted distribution in forested ridges on Newnes Plateau west of Sydney, Australia. We collated data and surveyed populations, undertook assessments of reproductive patterns (flowering; pollination; fruit set and fall), and modelled pollen dispersal among genets. We relate this assessment to planning approaches uninformed by genet structure and reproductive patterns. Small sites likely function as discrete populations, each with low numbers of genets. Genet diversity at this site scale is important as it is associated with increased fruit set. Loss of plants from populations poses a significant risk to population level fitness if genet diversity is reduced. There is an urgent need for more biologically informed approaches for the management of clonal plant species.

Operation strategy of cross-season solar heat storage heating system in an alpine high-altitude area

The full use of renewable energy sources such as solar energy to meet the various energy supply needs of buildings is now a research focus and an industry development trend, as energy consumption has been increasing and environmental pollution has become a serious problem. In the high-cold and high-altitude area in western China, due to the abundant solar energy and hydropower resources, the use of electric auxiliary cross-season solar heat storage heating system (CSHSHS) is an effective way to achieve clean heating. In this article, the authors applied a CSHSHS in a typical town in the Sichuan West Plateau and analysed and compared three operation strategies: heating storage priority control mode; electro-thermally assisted priority control mode and hybrid control mode. The results show that the heat storage priority control mode would require a large installed capacity of electrical auxiliary heat. The power consumption of the electro-thermally assisted priority control mode is high. The hybrid control mode can effectively reduce the installed capacity of the electrical auxiliary heat and the power consumption in the heating season. The solar fraction of the hybrid control mode was 38.29%, which has an obvious advantage. The results are of great engineering significance for optimizing the operation strategy of CSHSHS.

Spatiotemporal Dynamics of Precipitation in Southwest Arid-Agriculture Zones of Pakistan

Investigation of spatiotemporal precipitation trends from a climate change perspective is essential, especially in those regions with rainfed agriculture in order to propose sustainable adaptation schemes. Some restrictive assumptions may hinder the efficacy of trend detection methods, so it could be supported with variability analysis to have a clear picture of the spatiotemporal precipitation dynamics rather than focusing on a single approach. Hence, in the current study, a spatiotemporal dynamic analysis of precipitation was carried out using trend detection methods (the innovative trend analysis method and Mann–Kendall test) and statistical indices (the consecutive disparity index, entropy-based variability index and absolute inter-variability index) in the southwest arid region of Pakistan. The results indicated that based on the monthly, annual and seasonal time series, no systematic precipitation pattern was observed across the whole study region. However, on average, an increasing trend was observed in the east plateau while decreasing in the west plateau. The variability analysis also signposted the higher variability in the case of the western plateau and coastal area compared to the east plateau. Based on the seasonal analysis, it was concluded that, on average, precipitation in the winter and spring season goes on decreasing with higher variability while a mixture of increasing and decreasing trends resulted for summer and autumn. Conclusively the study found that precipitation in the study area is more erratic and its behaviour abruptly changed over a short distance. Moreover, discrepancies and inconstancies were found in the selected trend detection approaches and variability indices. The results also indicated that climate change is going to seriously affect the region as a decreasing trend prevails in most of the cases and stations.

Improved performance of a PRECIS ensemble in simulating near-surface air temperature over China

The near-surface air temperature over China is simulated from 1950 to 2099 using the PRECIS model from the Met Office Hadley Centre at a 25-km resolution. In order to reflect the different parametric and structural uncertainties in future temperature projections, the PRECIS model is driven by five lateral boundary conditions, which include a four-member HadCM3-based perturbed-physics ensemble (i.e., HadCM3Q0, Q1, Q7 and Q13) and an ECHAM5 model. For the present climate, PRECIS reasonably reproduces the spatial patterns of near-surface air temperatures over most regions in China, except for some underestimation in the west. The annual cycles of mean temperature are well captured but its magnitude is slightly underestimated throughout the year. Future temperature projections are further analyzed for three successive 30-year periods throughout the twenty-first century. Despite more uncertainties with time, the ensemble results demonstrate that the temperature over China is likely to continue to increase throughout the twenty-first century, with different spatial-time variation. There is an apparent increasing pattern along with the latitude for seasonal temperature. Through comparison with the driving GCMs, PRECIS ensemble shows smaller biases in most regions of China, except for in the west plateau. The cause is that RCMs could inherit some errors from the driving GCMs in addition to their own errors. These errors could be magnified unintentionally in downscaling over high elevations and have been propagated into future climate projections. However, there is no apparent relationship between projected changes and model biases (i.e., larger bias does not necessarily lead to bigger changes in temperature). These results could be directly used to analyze the impacts caused by climate warming on agriculture, energy and other related sectors in China.

Potencial erosivo da chuva na bacia hidrográfica do Córrego Baguaçu no estado de São Paulo

O presente estudo tem como objetivo determinar o índice de erosividade da chuva na bacia do Córrego Baguaçu, localizada no Planalto Ocidental do estado de São Paulo, região que apresenta problemas relacionados à erosão dos solos, constituídos por fatores antrópicos, como ausência ou uso incorreto de manejo, mas também por fatores intrínsecos, como a ocorrência de solos mais propensos a erosão. Utilizando dados de chuva, foi obtida uma estimativa do valor de EI30 para a bacia, permitindo futuros estudos de elaboração para planos de controle na minimização das perdas de solos e possibilitando o planejamento dos ciclos de cultivo das culturas agrícolas presentes.

Two new species of Clinopsalta Moulds (Hemiptera: Cicadidae) and additional distribution records for Clinopsalta adelaida (Ashton), with notes on their distinctive calling songs

Two new species are described in the genus Clinopsalta Moulds. Clinopsalta autumna sp. nov. exhibits a warm temperate distribution from south-east Queensland south to Goulburn and Nerriga in eastern New South Wales. Clinopsalta semilunata sp. nov. has a patchy distribution in southern Queensland from Binjour Plateau west to near Miles, south to Yelarbon State Forest and Durikai State Forest, both near Inglewood. In addition to the descriptions of these new species, further distribution records are provided for C. adelaida (Ashton), which extend its distribution from south-eastern South Australia and northern Victoria to inland central and northern New South Wales. The species of Clinopsalta are small–medium sized cicadas (< 20 mm body length) with distinctive calling songs of an intermediate frequency (c. 6 to 18 kHz). The temporal structures of the calling songs follow a similar pattern in each species, comprising an introductory rattle followed by a series of clicking phrases. The call is characteristically accompanied with bouts of prominent wing-snapping, except in one species (C. semilunata sp. nov.).

Building and breaking a large igneous province: An example from the High Arctic

AbstractThe genesis of the Amerasia Basin in the Arctic Ocean has been difficult to discern due to overprint of the Cretaceous High‐Arctic Large Igneous Province (HALIP). Based on detailed analysis of bathymetry data, new Arctic magnetic and gravity compilations, and recently published radiometric and seismic data, we present a revised plate kinematic model of the northernmost Amerasia Basin. We show that the smaller Makarov Basin is formed by rifting and seafloor spreading during the latest Cretaceous (to middle Paleocene). The opening progressively migrated into the Alpha Ridge structure, which was the focus of Early‐to‐Middle Cretaceous HALIP formation, causing breakup of the proto‐Alpha Ridge into the present‐day Alpha Ridge and Alpha Ridge West Plateau. We propose that breakup of the Makarov Basin was triggered by extension between the North America and Eurasian plates and possibly North Pacific plate rollback.

Studies of the Belukha glacier plexus in the context of global glacio-climatic monitoring (on the 100th anniversary of the first ascent of the Belukha Mountain)

The Belukha Mountain is the highest peak of the Altai. On July 26 (7 th August in the new time scale) of 1914 the brothers Boris and Mikhail Tronov discovered the mountain and were the first people to climb it. The Tronov Glacier is named after them. The Belukha glacier plexus is now subject to intensive degradation caused by current climate warming. There are changes in the processes of ice-forming, the temperature regime, and the stratigraphic characteristics. The mountain slope processes have become more active. The glacier length has decreased by 1.5–2.0 km, their area shortened almost by 20%, and the volume – by 10–12%. The snow-coverage of slopes has decreased, and positions of the ice-forming zones have correspondingly changed. Analysis of cores from the borehole drilled by the international expedition of 2003 on the west plateau of the Tronov Glacier has made it possible to better refine the character and seasonality of the glaciers alimentation. It is supposed that 11 thousand years ago no glacier existed here. The glacier plexus of the Belukha Mountain area is a natural reference point to monitor the state of glacierization and to justify predicted glacio-climatic situations. We propose to organize an international project aimed at the monitoring of these glacier areas and then to prepare a joint monograph devoted to its glacio-climatic characteristics. This could be performed in the framework of the Russian-Kazakh international programs with participation of scientists from other countries. Now is the right time to prepare summarizing monographs on glacierization of the main glacier clusters in the Russian mountains, similar to the series of books on representative glacier basins in USSR published in the 1980s. The Belukha glaciers should certainly be included in this series.

Factors affecting the visible southbound migration of raptors approaching a water surface

We investigated the visible migration of raptors when approaching a water surface in relation to local wind conditions, time of the day and topography. Observations were made during autumn migration in 2011 and 2012 at a watchsite located in the southernmost part of the Calabrian Apennines (southern continental Italy). In this area, the Apennines show differential topographical features with a plateau west of the mountain ridge. West–southwest of the plateau lies the Straits of Messina, the narrowest water surface between southern continental Italy and eastern Sicily. The passage of migrants was recorded along the ridge of the mountain chain and over the plateau. As expected for a soaring raptor, European Honey Buzzards were detected mostly during midday and early afternoon, while significant numbers were seen toward sunset probably when flying at lower altitude to roost. In addition, they were detected during strong winds when exploiting deflection updrafts, avoiding wind drift and limiting the negative effect of head winds. Western Marsh Harriers were detected mostly during crosswinds blowing from W–NW, perhaps because of a partial drift effect on birds passing along the Tyrrhenian coast. Black Kites were seen concentrating the passage over the plateau, confirming the hypothesis that these raptors tend to move along the western slope of the Italian peninsula perhaps because of foraging behaviour. Finally, European Kestrels/Lesser Kestrels were seen toward the sunset. This result seems to confirm that these small falcons migrate at considerable altitudes resulting in them being hardly detectable by direct visual observation but becoming more visible toward sunset, when they were probably moving to roost.

Травяные мелколиственные леса овражно-балочных систем Приобского плато (Западная Сибирь)

Small-leaved forests of the galley and ravine systems on the Priobskoe plateau (West Siberia) belong to the Brachypodio pinnati–Betuletea pendulae class and the Calamagrostio epigei–Betuletalia pendulae order. All forest types were classified according to the Braun-Blanquet approach. Three new associations and four subassociations were described. Floristic composition presented by mixture of forest, meadow and steppe species reveals the geographical position and the environmental conditions of forest habitats. Forest distribution depends on the slope exposition and steepness. In spite of strong anthropogenic pressure many of forest patches could be considered as refuges of natural biodiversity in forest-steppe zone.

Ice sheet grounding and iceberg plow marks on the northern and central Yermak Plateau revealed by geophysical data

We present new evidence for a grounded ice sheet and subsequent erosion by large fields of coherent icebergs for the central and northern Yermak Plateau (80.6°N to 82.2°N). Sediment echosounder and swath bathymetry data were combined with seismic reflection profiles and reveal at least three different glacial events marked by erosional unconformities: (i) An erosional unconformity was observed at ∼70–90 m below seafloor down to depths of more than 850 m present water depth, extending to ∼82°N. The erosional unconformity is overlain by an acoustically chaotic layer of ∼50 m thickness interpreted as a diamicton originating from a grounded ice sheet. The erosional unconformity and the overlying diamicton can be correlated to the overconsolidated sediments found at ODP Site 910 at a sediment depth between ∼19 and 70–95 m. The oldest sediments just above the overconsolidated sediments are of late Early Pleistocene age (MIS19/20) and provide a minimum age for the grounding event. (ii) Parallel to sub-parallel mega-scale lineations are observed on large parts of the plateau west and northeast of the Sverdrup Bank at water depths between 725 and 850 m. These lineations are mainly oriented NNE-SSW and were quite likely formed by the keels of deep-draft, mega-scale tabular icebergs entrapped in a coherent mass of icebergs and sea ice. The lineations are of late Middle Pleistocene age. (iii) Smaller-scale curvilinear plow marks were found in the southernmost part of our study area at water depths between 640 and 775 m. These were possibly caused by single icebergs and are of Late Pleistocene age. Iceberg scours are also found on three basement heights on the Yermak Plateau. These, however, cannot be assigned to specific events; they might as well originate from additional glacial phases. The western (at >850 m water depth) and eastern (at >1000–1200 m water depth) flanks of the Yermak Plateau are relatively featureless, and indicate the maximum depth of a grounded ice sheet and of iceberg armadas probably entrapped in sea ice.

InSAR maps and time series observations of surface displacements of rock salt extruded near Garmsar, northern Iran

Abstract: A large allochthonous sheet of Eocene rock salt is forming the Eyvanekey plateau west of Garmsar along the northern periphery of the Great Kavir basin. This salt extruded over the central plains of Iran, where the southward advancing front of the Alborz Mountains is offset by the NE–SW-trending Zirab–Garmsar strike-slip fault. Based on nine descending Advanced Synthetic Aperture Radar images, produced by the European Space Agency's ENVISAT satellite from 2003 to 2006, we used interferograms to map the displacement over 22 increments ranging in time from 2 to 18 months. To study the surface deformation at high temporal and spatial resolution, a small subset of interferograms was used to map the mean velocity of surface deformation. The results suggest that the top of the salt is subsiding continuously at rates that depend on the season. The surface displacement rate throughout the region ranges from subsidence of −40 to −50 mm a −1 to uplift of 20 mm a −1 . The agricultural lowlands, where groundwater extraction for irrigation exceeds recharge, are subsiding faster than the salt sheet. Correlation of surface displacements with active folds and seismic faults around the salt sheet also suggests that the study area is undergoing active deformation. Supplementary material: Interferogram for the period 19.08.2003–14.02.2006 is available at http://www.geolsoc.org.uk/SUP18383 .

Horizontal gene transfer and recombination shape mesorhizobial populations in the gene center of the host plantsAstragalus luteolusandAstragalus ernestiiin Sichuan, China

Thirty-three rhizobial strains isolated from the root nodules of Astragalus luteolus and Astragalus ernestii growing on the west plateau at two different altitudes in Sichuan province, China, were characterized by amplified rDNA restriction analysis (ARDRA), amplified fragment length polymorphism (AFLP), and by sequencing of rrs, glnA, glnII and nifH. The ARDRA analysis revealed considerable genomic diversity. In AFLP analysis, 20 of 33 Astragalus rhizobia formed three distinct clades, with others dispersed into different groups with the reference strains. Phylogenetic analysis of the rrs gene of six representative strains showed that the isolates were members of the genus Mesorhizobium. Three of the isolates formed a sister clade to Mesorhizobium loti and Mesorhizobium ciceri, whereas the other three formed a sister clade to a clade harboring the species Mesorhizobium huakuii, Mesorhizobium plurifarum, Mesorhizobium septentrionale and Mesorhizobium amorphae, indicating the existence of two new species. Phylogenetic analysis of glnA and glnII confirmed the rrs phylogenies for four strains, but the trees were incongruent. The nifH sequences of the strains formed a monophyletic clade and were typical of those of mesorhizobia forming symbioses with inverted repeat lacking clade legume species. The incongruent phylogenies of the genes studied suggest that horizontal gene transfer and recombination shape mesorhizobial populations in the gene center of the host plants.

Genetic diversity and zebu genes introgression in cattle population along the coastal region of the Bight of Benin

SummaryGenetic diversity and Zebu genetic introgression have been assessed in five subpopulations of cattle along the coastal region of Togo, Benin and Nigeria using 15 autosomal and one Y- specific microsatellite markers. Mean observed heterozygosity (Ho) ranges from 0.55 to 0.61 and the mean number of alleles (MNA) from 5.47 to 6.47. Genetic differentiation indexes (Fst), were significant between the five subpopulations (P&lt; 0.01). Some possible population diagnostic alleles are identified with allele 254 at locus ILSTS033 and allele 182 at locus ILSTS005 found only in the population from Togo with frequencies of 5.41% and 12.82% respectively. Allele 226 of locus ILSTS103 is fixed in the Togolese population (100%) and almost fixed (98.75%) in the Benin-Valley population. Y chromosome analysis reveals male Zebu introgression in all five populations with a frequency of indicine Y chromosome ranging from 37.5% in Benin-Valley and Benin Plateau East to 100% for Benin Plateau West. Admixture analysis using the programme STRUCTURE (k = 2) confirms phenotypic observations suggesting different level of taurine background and therefore Zebu introgression amongst the populations. Within populations, variations in levels of Zebu admixture between herds were also detected. Whereas the valley population from Benin shows low level of Zebu introgression, it is the population from Benin Plateau East which is the purest.

First Evaluation of Human Sperm Quality in Various Geographic Regions of Switzerland

A decline in human sperm quality and quantity has been reported in numerous Western countries. This observation was also accompanied by an increase in urogenital malformations. The need for epidemiological studies dealing with unbiased populations in order to understand the causes of these observations is obvious. In Switzerland, the large majority of young men are asked to attend a military camp to be drafted into the army. A few weeks before this camp, conscripts were contacted and invited to participate in a large national study on semen quality. The participation was totally voluntary and anonymous. From September 2005 to June 2007, 770 volunteers filled out a questionnaire, underwent a clinical examination and provided sperm, blood and urine samples. Using self-rated health assessments, the observed cohort could be considered as healthy and no testicular cancer was found. Moreover, the testicular volumes, measured using Prader's orchidometry and ultrasonography, were comparable to those already published for young male populations. The median sperm concentration was 47 × 106/ml, which is close to the concentration reported in Denmark, known to have the highest incidence of testicular cancer in Europe. Statistically significant differences were observed between regions with a lower sperm concentration for men residing in the Alps (43 × 106/ml) and in the Zürich area (36 × 106/ml) compared to men from West Plateau (54 × 106/ml) and from the Jura (54 × 106/ml). Such a regional discrepancy could be related to environmental factors, including endocrine disruptors. In order to confirm such regional differences more volunteers from the already studied regions should be studied and other parts of the country should be investigated. The rather low sperm concentration of Swiss young volunteers should be considered as a national health issue and investigated further.

Prostanthera junonis Conn (LAMIACEAE); is recovery possible?

Prostanthera junonis is an endangered plant from the Somersby plateau west of Gosford, New South Wales. Most populations occur in sites modified by clearing or adjacent to developments. This paper examines the current status and recovery efforts for this species in the light of research to date. Studies undertaken indicate that the species has the reproductive ecology expected of a colonising species. Autogamy, a low pollen/ovule ratio, higher seed set in open sites compared with densely vegetated sites, clonal growth, a long flowering period and flowering by young plants were recorded for the species. It is predicted that these reproductive traits should help the population recover from clearing. Comments on recovery planning are made.

Late Cenozoic to Holocene deformation in southwestern Sichuan and adjacent Yunnan, China, and its role in formation of the southeastern part of the Tibetan Plateau

From at least 2–4 Ma to present, crust in the southeastern part of the Tibetan Plateau west of the convex-east Xianshuihe-Xiaojiang fault system has deformed internally and rotated clockwise around the eastern Himalayan syntaxis. The northwest-striking Ganzi fault zone bounds the rotating crust on the north and has a total left slip of 78–100 km, of which ∼60 km is transferred to the Xianshuihe fault zone across a diffuse transfer zone, and ∼22–40 km is absorbed by bending of older structures and crustal shortening. Crustal shortening is expressed along and east of the eastern end of the Ganzi fault zone by mountains capped by permanent glaciers locally rising nearly 1000 m above the average elevation of the Tibetan Plateau. A similar transfer of left slip into shortening occurs farther south across the Xianshuihe fault in the high mountains around and east of Gongga Shan (7556 m). The northwest-striking, convex-east, left-lateral Litang fault zone lies southwest of the Ganzi-Xianshuihe-Xiaojiang fault zone and appears to be less well developed but otherwise similar to the Ganzi fault zone. The Batang, Chenzhi, and other northeast-striking right-lateral faults of small displacement occur within the rotating crustal fragment. Together with the left-slip faults, they accommodate east-west shortening northeast of the eastern Himalayan syntaxis. South of this region of shortening, the crust is extending to form grabens within the Dali and southern Xiaojiang fault systems and in the Tengchong volcanic province. The progressive change from shortening southward into extension is related to variations in strain that characterize the region from northeast to southeast of the eastern Himalayan syntaxis. The assemblage of structures in southwestern Sichuan geometrically resembles structures of Eocene to Miocene age in southern Yunnan that were positioned northeast of the eastern Himalayan syntaxis, similar to present-day southwestern Sichuan, at the time of their development. The similarity in the structural development in the two areas indicates that crust northeast of the syntaxis underwent a common evolution as the syntaxis migrated northward during the past ∼50 m.y. Structures in Sichuan are less fully developed than older structures in southwestern Yunnan and can serve as a guide to reconstruct the progressive tectonic development in the region of the syntaxis. Deformation in these areas indicates that plateau formation has been complex, inhomogeneous, and diachronous at scales from 1000 km to less than 100 km.