Holocene history of earthflow mass movements in south-central British Columbia: the influence of hydroclimatic changes

1992 ◽  
Vol 29 (8) ◽  
pp. 1746-1755 ◽  
Author(s):  
Michael J. Bovis ◽  
Penny Jones

Large earthflows in south-central British Columbia have exhibited regionally consistent fluctuations in their movement during the Holocene. Over the past 60 years, air photographs show that many earthflows were reactivated during the relatively wet period 1950–1985. Over the past 300 years, a fairly coherent relationship is established between periods of wetter climate, defined by the tree-ring record, and phases of slope movement, defined by the record of compression-wood development in conifers located near earthflow headscarps. On a time scale of several thousand years, stratigraphic evidence shows that many large earthflows in the region underwent significant reactivation of movement in the post-Mazama period, during the relatively wet, cool Neoglacial interval of the Holocene. These lines of evidence indicate that Holocene hydroclimatic changes have exerted an important influence on the regimen of large earthflows. Earthflows present a wealth of paleogeomorphic information, hitherto largely neglected, that allows a reconstruction of the changing rate of mass movement with time.

2017 ◽  
Vol 54 (11) ◽  
pp. 1153-1164 ◽  
Author(s):  
B.H. Luckman ◽  
M.H. Masiokas ◽  
K. Nicolussi

As glaciers in the Canadian Rockies recede, glacier forefields continue to yield subfossil wood from sites overridden by these glaciers during the Holocene. Robson Glacier in British Columbia formerly extended below tree line, and recession over the last century has progressively revealed a number of buried forest sites that are providing one of the more complete records of glacier history in the Canadian Rockies during the latter half of the Holocene. The glacier was advancing ca. 5.5 km upvalley of the Little Ice Age terminus ca. 5.26 cal ka BP, at sites ca. 2 km upvalley ca. 4.02 cal ka BP and ca. 3.55 cal ka BP, and 0.5–1 km upvalley between 1140 and 1350 A.D. There is also limited evidence based on detrital wood of an additional period of glacier advance ca. 3.24 cal ka BP. This record is more similar to glacier histories further west in British Columbia than elsewhere in the Rockies and provides the first evidence for a post-Hypsithermal glacier advance at ca. 5.26 cal ka BP in the Rockies. The utilization of the wiggle-matching approach using multiple 14C dates from sample locations determined by dendrochronological analyses enabled the recognition of 14C outliers and an increase in the precision and accuracy of the dating of glacier advances.


2019 ◽  
Author(s):  
S. V. Dryomov ◽  
A. M. Nazhmidenova ◽  
E. B. Starikovskaya ◽  
S. A. Shalaurova ◽  
N. Rohland ◽  
...  

AbstractThe Central Siberian Plateau was last geographic area in Eurasia to become habitable by modern humans after the Last Glacial Maximum (LGM). Through comprehensive mitochondrial DNA genomes retained in indigenous Siberian populations, the Ket, Tofalar, and Todzhi - we explored genetic links between the Yenisei-Sayan region and Northeast Eurasia over the last 10,000 years. Accordingly, we generated 218 new complete mtDNA sequences and placed them into compound phylogenies along with 7 newly obtained and 70 published ancient mt genomes. Our findings reflect the origins and expansion history of mtDNA lineages that evolved in South-Central Siberia, as well as multiple phases of connections between this region and distant parts of Eurasia. Our result illustrates the importance of jointly sampling modern and prehistoric specimens to fully measure the past genetic diversity and to reconstruct the process of peopling of the high latitudes of the Siberian subcontinent.


1996 ◽  
Vol 70 (2) ◽  
pp. 280-293 ◽  
Author(s):  
Desmond Collins

The remarkable “evolution” of the reconstructions of Anomalocaris, the extraordinary predator from the 515 million year old Middle Cambrian Burgess Shale of British Columbia, reflects the dramatic changes in our interpretation of early animal life on Earth over the past 100 years. Beginning in 1892 with a claw identified as the abdomen and tail of a phyllocarid crustacean, parts of Anomalocaris have been described variously as a jellyfish, a sea-cucumber, a polychaete worm, a composite of a jellyfish and sponge, or have been attached to other arthropods as appendages. Charles D. Walcott collected complete specimens of Anomalocaris nathorsti between 1911 and 1917, and a Geological Survey of Canada party collected an almost complete specimen of Anomalocaris canadensis in 1966 or 1967, but neither species was adequately described until 1985. At that time they were interpreted by Whittington and Briggs to be representatives of “a hitherto unknown phylum.”Here, using recently collected specimens, the two species are newly reconstructed and described in the genera Anomalocaris and Laggania, and interpreted to be members of an extinct arthropod class, Dinocarida, and order Radiodonta, new to science. The long history of inaccurate reconstruction and mistaken identification of Anomalocaris and Laggania exemplifies our great difficulty in visualizing and classifying, from fossil remains, the many Cambrian animals with no apparent living descendants.


2011 ◽  
Vol 48 (6) ◽  
pp. 870-896 ◽  
Author(s):  
Janet Riddell

The south-central Intermontane belt of British Columbia has a complex architecture comprising late Paleozoic to Mesozoic volcanic and plutonic arc magmatic suites, marine and nonmarine clastic basins, high-grade metamorphic complexes, and accretionary rocks. Jurassic and Cretaceous clastic basins within this framework contain stratigraphy with hydrocarbon potential. The geology is complicated by Cretaceous to Eocene deformation, dismemberment, and dislocation. The Eocene to Neogene history of the southern Intermontane belt is dominated by non-arc volcanism, followed by Pleistocene to Recent glaciation. The volcanic and glacial cover makes this a difficult region to explore for resources. Much recent work has involved re-evaluating the challenges that the overlying volcanic cover has historically presented to geophysical imaging of the sedimentary rocks in this region in light of technological advances in geophysical data collection and analysis. This paper summarizes the lithological and stratigraphic framework of the region, with emphasis on description of the sedimentary units that have been the targets of hydrocarbon exploration.


1975 ◽  
Vol 12 (10) ◽  
pp. 1760-1769 ◽  
Author(s):  
Andrew V. Okulitch ◽  
R. K. Wanless ◽  
W. D. Loveridge

An apparently tabular body of granitoid gneiss, 3 to 5 km wide and more than 70 km long, that lies along the western margin of the Shuswap Metamorphic Complex between Shuswap and Admas Lakes, shows intrusive relationships with Palaeozoic and older rocks and has yielded zircons whose minimum age is 372 Ma. This intrusion, together with other granitoid plutons in the area that appear to be related to it, provide evidence of widespread plutonism during Middle Devonian time near the western edge of the Paleozoic Cordillera geosyncline and necessitate significant revisions in the interpretation of the crustal history of this region.


2003 ◽  
Vol 33 (1) ◽  
pp. 59-86
Author(s):  
John S. Levin

This qualitative investigation identifies a condition of frenetic change experienced by organizational members at two university col- leges in British Columbia, Canada, during the past decade. Prominent outcomes of the formal designation of five former community colleges as university colleges included curricular change and the evolution of a new institutional mission. The brief history of the university colleges of British Columbia parallels the process of economic globalization in the province of British Columbia, and the responses of managers and faculty at university colleges indicate that globalization influenced the formation and functioning of these institutions.


Author(s):  
Veronika Ryjik

This chapter surveys the history of Russian translations of Golden Age Spanish theatre from the early 18th century until now, with a special focus on the relationship between translation trends and performance history. Our main goal is not only to document all known Russian translations of Spanish classical plays completed in the past 300 years, but also to elucidate the processes by which translation took part in the development and transformation of a specifically Russian comedia canon.


2010 ◽  
Vol 74 (1) ◽  
pp. 23-25 ◽  
Author(s):  
Sonja Berg ◽  
Bernd Wagner ◽  
Duanne A. White ◽  
Martin Melles

AbstractThe history of glacial advances and retreats of the East Antarctic ice sheet during the Holocene is not well-known, due to limited field evidence in both the marine and terrestrial realm. A 257-cm-long sediment core was recovered from a marine inlet in the Rauer Group, East Antarctica, 1.8 km in front of the present ice-sheet margin. Radiocarbon dating and lithological characteristics reveal that the core comprises a complete marine record since 4500 yr. A significant ice-sheet expansion beyond present ice margins therefore did not occur during this period.


2021 ◽  
Vol 4 ◽  
Author(s):  
Axel Bohmann ◽  
Martin Bohmann ◽  
Lars Hinrichs

We explore the relationship between word dissemination and frequency change for a rapidly receding feature, the relativizer whom. The success of newly emerging words has been shown to correlate with high dissemination scores. However, the reverse—a correlation of lower dissemination scores with receding features—has not been investigated. Based on two established and two newly developed measures of word dissemination—across texts, linguistic environments, registers, and topics—we show that a general correlation between dissemination and frequency does not obtain in the case of whom. Different dissemination measures diverge from each other and show internally variable developments. These can, however, be explained with reference to the specific sociolinguistic history of whom over the past 300 years. Our findings suggest that the relationship between dissemination and word success is not static, but needs to be contextualized against different stages in individual words’ life-cycles. Our study demonstrates the applicability of large-scale, quantitative measures to qualitatively informed sociolinguistic research.


2021 ◽  
Vol 13 (17) ◽  
pp. 9469
Author(s):  
Valentino Romano ◽  
Giulio Catalano ◽  
Giuseppe Bazan ◽  
Francesco Calì ◽  
Luca Sineo

The Mediterranean islands and their population history are of considerable importance to the interpretation of the population history of Europe as a whole. In this context, Sicily, because of its geographic position, represents a bridge between Africa, the Near East, and Europe that led to the stratification of settlements and admixture events. The genetic analysis of extant and ancient human samples has tried to reconstruct the population dynamics associated with the cultural and demographic changes that took place during the prehistory and history of Sicily. In turn, genetic, demographic and cultural changes need to be understood in the context of the environmental changes that took place over the Holocene. Based on this framework, this paper aims to discuss the cultural and demographic dimension of the island by reviewing archaeogenetic studies, and lastly, we discuss the ecological constraints related to human peopling in times of change in landscapes that occurred on the island in various periods. Finally, possible directions for future archaeogenetic studies of Sicily are discussed. Despite its long human history, Sicily is still one of the world’s biodiversity hotspots. The lessons we learn from the past use of landscape provide models for sustainable future management of the Mediterranean’s landscapes.


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