89 research outputs found
Holocene glacier variations and their potential orbital, solar, volcanic and anthropogenic forcings
Get PDFThe magnitude of glacier advances generally increased in the Northern Hemisphere and decreased in the Southern Hemisphere over the Holocene. This trend can be explained be the orbital forcings. The exceptions are in some regions of the high Asia. 10–4 ka BP and during the 1th Century CE to the early 13th century CE the glaciers were close by sizes to the modern ones or even smaller. The pattern is confirmed by the upper and Northern tree line advances in the Northern Hemisphere. The period with generally «small glaciers» (5–7 ka) coincides with the lack of the major volcanic eruptions, and with the low solar activity. The Early Holocene moraines cluster in seven groups (from 11.1 to 8.1 ka BP). They coincide with all Early Holocene Bond cycles (11.1, 10.3, 9.4, 8.1 ka) and all major volcanic eruptions (11.0, 9.5–9.7, 9.1–9.3, 8.0–8.1). Due to the coincidence of several eruptions with the Bond cycles (solar minima) it is difficult to distinguish between the solar and volcanic signals in the Early Holocene records. The coupling between the glacial and solar/volcanic forcings in the mid Holocene is less evident, but it become strong again in the last 2 ka (1.4 ka and LIA events). The modern glacier retreat disagrees with the actual orbital forcings and is due to both solar and anthropogenic influence. Glacier variations at the moment do not provide proofs for any cycles or global synchronism through the Holocene. However the lack of such evidences can be also explained by the limitations of these records (discontinuous, incomplete, of low accuracy, showing a mixture of advances triggered by both temperature and precipitation)
KASHKATASH GLACIER FLUCTUATIONS IN THE XVII–XXI CENTURIES FROM CARTOGRAPHIC, DENDROCHRONOLOGICAL AND LICHENOMETRIC DATA
No full textWe focused our study on the retreat of a typical valley glacier Kashkatash, located in the Elbrus Area. We compared the old photographs of the glacier forefields (H. Burmester, 1911; H. Altberg, 1927; E.N. Lukasheva, 1932; unknown author, 1939) with the aerial photograph of 1957, 1965, 1987, maps of scale 1:100 000 (1890) and 1:25 000 (1950s), satellite images (CORONA of 1971, ASTER of 2005, EROS of 2006), oblique photographs taken in 1980s–2000s and plans, created by different researches. Using cartographic material and old photographs we reconstructed 14 positions of glacier tongue over the last 120 years. We estimated the linear glacier retreat and the age of numerous stadial moraines basing on geomorphic, tree-ring and lichenometric data and correlated our results with previous sparse glacier fluctuation reconstructions in this region. We identified at least 13 end moraines within the distance of 900 meters from the up-to-date glacier front position. The minimum age of the outer moraine is 450 years according to the tree-ring data. One tree growing on this moraine was damaged by a boulder falling down from a younger moraine under formation in the period from autumn 1839 to spring 1840. Three moraines were deposited in 1870s–1890s. In 20th century the glacier advanced in 1910-s, 1920-s, and 1970–1980-s
Ground surface temperature variations on Kunashir Island in the last 400 years inferred from borehole temperature data and tree-ring records
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Cyclicity of natural processes in the last 300 years imprinted in the Tree-Ring proxies in Subarctic European Russia revealed by wavelet analysis
No full textUsing information-communication technologies in educational process organization
Get PDF© 2017. revistaESPACIOS.com. The article addresses the influence of informationcommunication technologies on the development and improvement of informational-educational environment of a modern university. It defines the tendencies of further development and methods of information and Internet technologies' application in informationaleducational environment of a university. The article presents and analyzes the results of a survey among students with the aim of revealing the level of activity in using informational-educational environment in the educational process. The following phenomena were defined as the tendencies of the development of informational-educational environment of a university: processes of converting universities' documents, document flows and communication channels to the electronic format; active introduction and use of electronic educational and educational-methodic documents; decrease of expenses related to the support of communication process, increase of its efficiency and accessibility of its results not only for university students and teachers but for the society in general by using the "free ware" type software. Control of students' knowledge is an important stage in the educational process. If the tests are designed correctly, students' knowledge, abilities and skills are reflected in the performance of the control tests' tasks. Knowledge control in the StartExam program is one the possible ways of increasing the efficiency of students' knowledge control and teacher's work capacity
Using information-communication technologies in educational process organization
No full text© 2017. revistaESPACIOS.com. The article addresses the influence of informationcommunication technologies on the development and improvement of informational-educational environment of a modern university. It defines the tendencies of further development and methods of information and Internet technologies' application in informationaleducational environment of a university. The article presents and analyzes the results of a survey among students with the aim of revealing the level of activity in using informational-educational environment in the educational process. The following phenomena were defined as the tendencies of the development of informational-educational environment of a university: processes of converting universities' documents, document flows and communication channels to the electronic format; active introduction and use of electronic educational and educational-methodic documents; decrease of expenses related to the support of communication process, increase of its efficiency and accessibility of its results not only for university students and teachers but for the society in general by using the "free ware" type software. Control of students' knowledge is an important stage in the educational process. If the tests are designed correctly, students' knowledge, abilities and skills are reflected in the performance of the control tests' tasks. Knowledge control in the StartExam program is one the possible ways of increasing the efficiency of students' knowledge control and teacher's work capacity
Absolute and relative age of moraines of the Aktru and Historical stages of glaciers of Central Altai based on lichenometry and dendrochronology
Get PDFDendrochronology, and lichenometry were used to determine the relative and absolute age of the Late Holocene moraines of the glaciers of the Aktru, Maashei and Shavla valleys (North Chuya ridge, Central Altai). An array of 86dendrochronological dates, related to moraine deposits, is analyzed, 30 of which are published for the first time. Also, for the first time, data on the relative (lichenometric) age of the young deposits of the Aktru Valley, and data on the lichenometry of the moraines of the Maashey glacier and one of the glaciers of the Shavly valley were obtained. We used the capabilities of each method and the expediency of their combined use in the study area. It was confirmed that the growth rates of lichens on the moraines of the Aktru stage (XVIII–XIX centuries) are generally consistent with the previously published estimates. The moraines of the Historical stage, which date earlier than 1700–2300 years ago, supports the lichens as large as 120–160 mm, but the scattering of their diameters is too large and the assessment of the lichenometric ages of these moraines seems to be problematic, but not completely excluded. The Akkem stage of glacier advance according to the recent publications dates back to the Late Glacial or Early Holocene time; the lichenometry is obviously not applicably at such ancient surfaces. According to dendrochronological dating, the glaciers of the North Chuisky Ridge in the last millennium advanced at least twice up to their maximum extent in the XVII– early XIX and XII centuries. In the 8th century, the sizes of the glaciers possibly, approached modern ones. Aſter the XVII century, the cedar (Pinus Sibirica) in Central Altai significantly reduced its distribution area due to the climate cooling, retreating from the periglacial territories, where it was distributed earlier. All trees that grew near the glaciers, above 2300 m, died. The comparison of the dates of glacier advances in the past millennia with the tree-ring, ice-core, and palynological reconstructions of summer temperature and precipitation show a good correspondence
“Little Ice Age” glaciers in Kamchatka, northeastern Russia
No full textLichenometry was used to date “Little Ice Age” moraines in the Kamchatka peninsula, northeastern Russia. The Rhizocarpon geographicum growth-rate curve was based on seven data points from lava flows and moraines, dated using historical records or tephrochronology (15–300 BP). No reduction in growth rate due to decreasing lichen age was observed, so a linear approximation was used. Accuracy test results yield differences between real and calculated dates up to, but not exceeding, five years. From eight “Little Ice Age” (LIA) moraines it was established that Kamchatka glaciers advanced in the 1690s, 1850–70 and 1910–20. Only one moraine clearly corresponded to the 1690s advance. The maximum stage of the LIA was during the mid- to late 19th century when glacier fronts were generally 100–200 m lower than at present. Glacier termini with ash and moraine layers, covered by lichens and vascular plants, have been preserved for 150–300 years, judging by the lichen sizes.</jats:p
First <sup>10</sup>Be dates of late holocene moraines of the Kashkatash and Irik glaciers, Northern Caucasus
No full textWe present 11 10Be ages of the moraines of the Irik and Kashkatash glaciers that allowed identifying and dating several Late Holocene glacier advances for the first time, including a prominent advance exceeding the Little Ice Age (LIA) maximum that occurred at 1.6–1.7 ka at еру Irik Glacier. The advance is dated by the three very close 10Be ages of a moraine (1.57 ± 0.23 ka, 1.63 ± 0.23, and 1.68 ± 0.24 ka) located in the vicinity of the moraines of the Little Ice Age (LIA) maximum advance. The advance that occurred at 1.6–1.7 ka might be a possible analogue of the “Historical” stage described earlier in the Caucasus in literature basing at geomorphic evidence, speculations, and analogues with other mountain regions, but not dated. Another possibility is a potential correlation of this advance with the Late Antique Little Ice Age cooling in 536 to ~660 CE. The age of Irik Glacier advance is close to the humid period identified in the Garabashi (Baksan, Elbrus valley) lake sediments at 1500–1700 years BP. The magnitude of the identified glacier advances over the past two millennia was similar. Between the advance of 1.6–1.7 ka and the position of the glacier in 2022 CE the elevation of the Irik Glacier front increased by 520 m from 2490 to 3010 m asl. Four 10Be dates (0.7 + 0.11, 0.72 + 0.11, 0.77 + 0.11 and 0.82 + 0.18 ka) of the lateral moraine of the Kashkatash Glacier constrain the advance of the first stage of the LIA. The advance of the 13th century is also dated by 10Be at the DonguzOrun and Chalaati glaciers located at the Northern and Southern slopes of the Caucasus, respectively. The corresponding cooling in ca 1250–1400 CE is identified in the sedimentary paleoclimatic proxies of Lake Karakel (Teberda valley). A later advance at the Kashkatash Glacier is constrained by only one 10Be date (0.53 ± 0.13 ka) and needs further confirmation. Till deposited between the 1490s and 1640s at the Greater Azau Glacier is close to the date of this advance of the Kashkatash Glacier. A cooling at that time is recorded in the proxies of Karakel Lake sediments (1500–1630 CE). Three other 10Be dates of two earlier advances at 0.25 + 0.04 ka and between 0.14 + 0.03 and 0.16 ± 0.02 ka at Kashkatash Glacier are indirectly supported by tree-ring, lake sediment, 14C, and historical data. Further research and new data is necessary to increase the credibility and accuracy of the dates of glacier advances of the Late Holocene in the Northern Caucasus
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