Landsliding caused by Pleistocene glacial lake ponding–an example from central British Columbia

1987 ◽  
Vol 24 (4) ◽  
pp. 656-663 ◽  
Author(s):  
N. Eyles ◽  
John J. Clague

Sections cut through the Quaternary sediment fill of the Fraser River valley in central British Columbia provide evidence for large-scale landsliding during Pleistocene time. Especially notable are thick, laterally extensive diamict beds, consisting mainly of Tertiary rock debris, that occur near the base of glaciolacustrine sequences. These beds were deposited by subaqueous debris flows during one or more periods of lake ponding when advancing Pleistocene glaciers blocked the ancestral Fraser River. The association of diamict beds and glaciolacustrine sediments deposited during periods of glacier advance may indicate a genetic link between slope failure and lake filling. These observations (1) demonstrate the adverse effects of high pore pressures on the stability of slopes underlain by poorly indurated Tertiary rocks and (2) extend the known history of landslides involving these rocks back into the Pleistocene. Key words: landslides, debris flows, Pleistocene, glacial lake.


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.



2016 ◽  
Vol 145 (2) ◽  
pp. 348-362 ◽  
Author(s):  
Richard J. Beamish ◽  
Chrys M. Neville ◽  
Ruston M. Sweeting ◽  
Terry D. Beacham ◽  
Joy Wade ◽  
...  




2018 ◽  
Author(s):  
Jennifer Bastart ◽  
Richard Anthony Klein ◽  
Hans IJzerman

Replication is one key component towards a robust cumulative knowledge base. It plays a critical function in assessing the stability of the scientific literature. Replication involves closely repeating the procedure of a study and determining if the results are similar to the original. For decades, behavioral scientists were reluctant to publish replications. Reasons were epistemic and pragmatic. First of all, original studies were viewed as conclusive in most cases, and failures to replicate were often attributed to mistakes by the replicating researcher. In addition, failures to replicate may be caused by numerous factors. This inherent ambiguity made replications less desirable to journals. On the other hand, replication successes were expected and considered to contribute little beyond what was already known. Finally, editorial policies did not encourage the publication of replications, leaving the robustness of scientific findings largely unreported. A series of events ultimately led the research community to reconsider replication and research practices at large: the discovery of several cases of large-scale scientific misconduct (i.e., fraud), the invention and/or application of new statistical tools to assess strength of evidence, high-profile publications suggesting that some common practices may be less robust than previously assumed, failure to replicate some major findings of the field, and the creation of new, online tools aimed to promote transparency in the field. To deal with what is often regarded as the crisis of confidence, initiatives have been developed to increase the transparency of research practices, including (but not limited to) pre-registration of studies, effect size predictions and sample size/power estimation, and, of course, replications. Replication projects themselves evolved in quality: From replications that were originally as small in sample as problematically small original studies to large-scale “Many Labs” collaborative projects. Ultimately, the development of higher quality replication projects and open science tools has led (and will continue to lead) to a clearer understanding of human behavior and cognition and have contributed to a clearer distinction between exploratory and confirmatory behavioral science. The current bibliography gives an overview of the history of replications, of the development of tools and guidelines, and of review papers discussing theoretical implications of replications.



Geosciences ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 417 ◽  
Author(s):  
Abbate ◽  
Longoni ◽  
Ivanov ◽  
Papini

Landslides over steep slopes, floods along rivers plains and debris flows across valleys are hydrogeological phenomena typical for mountain regions. Such events are generally triggered by rainfall, which can have large variability in terms of both its intensity and volume. Furthermore, terrain predisposition and the presence of some disturbances, such as wildfires, can have an adverse effect on the potential risk. Modelling the complex interaction between these components is not a simple task and cannot always be carried out using instability thresholds that only take into account the characteristics of the rainfall events. In some particular cases, external factors can modify the existing delicate equilibrium on the basis of which stability thresholds are defined. In particular, events such as wildfires can cause the removal of vegetation coverage and the modification of the soil terrain properties. Therefore, wildfires can effectively reduce the infiltration capacity of the terrain and modify evapotranspiration. As a result, key factors for slope stability, such as the trend of the degree of saturation of the terrain, can be strongly modified. Thus, studying the role of wildfire effects on the terrain’s hydrological balance is fundamental to establish the critical conditions that can trigger potential slope failures (i.e., shallow landslides and possible subsequent debris flows). In this work, we investigate the consequences of wildfire on the stability of slopes through a hydrological model that takes into account the wildfire effects and compare the results to the current stability thresholds. Two case studies in the Ardenno (IT) and Ronco sopra Ascona (CH) municipalities were chosen for model testing. The aim of this paper is to propose a quantitative analysis of the two cases studies, taking into account the role of fire in the slope stability assessment. The results indicate how the post-fire circumstances strongly modify the ability of the terrain to absorb rainfall water. This effect results in a persistently drier terrain until a corner point is reached, after which the stability of the slope could be undermined by a rainfall event of negligible intensity.



1991 ◽  
Vol 28 (10) ◽  
pp. 1583-1593 ◽  
Author(s):  
Allen S. Gottesfeld ◽  
Rolf W. Mathewes ◽  
Leslie M. Johnson Gottesfeld

Debris flow deposits of Chicago Creek and the sediment, pollen, and macrofossil records of Seeley Lake were studied to elucidate the Holocene history of the northwest flank of the Rocher Déboulé Range near Hazelton, British Columbia.The Chicago Creek drainage has experienced numerous rockfalls, debris slides, and debris flows. A large debris flow covering approximately 300 ha occurred about 3580 ± 150 BP. This flow was two to three orders of magnitude larger than historic debris flows in this drainage. It traveled about 3 km down Chicago Creek and dammed the outlet stream of Seeley Lake. A debris deposit along lower Chicago Creek is interpreted as the product of debris torrents that formed during or soon after the damming of Seeley Lake. Its surface exhibits soil development (rubification and profile development) comparable to that on the large debris flow, suggesting equivalent age.Pollen and plant macrofossils are described from a core taken in Seeley Lake. This core spans the period from ca. 9200 BP to the present. A disturbance event in 3380 ± 110 BP, correlative with the large Chicago Creek debris flow, is recorded by a clastic sediment layer and changes in the microfossil and macrofossil assemblages.The Chicago Creek debris flow and debris torrent ca. 3500 BP may be the catastrophic event recorded in the story of the Medeek, an oral history or "ada'ok" of the Gitksan people of Hazelton.



1982 ◽  
Vol 19 (3) ◽  
pp. 524-539 ◽  
Author(s):  
J. J. Clague ◽  
J. G. Souther

A large (ca. 5 × 106 m3) landslide occurred on the west flank of Mount Cayley in the southern Coast Mountains of British Columbia in 1963. Failure commenced when a large block of poorly consolidated tuff breccia and columnar-jointed dacite was detached from the subvolcanic basement and slid into the valley of Dusty Creek, a small tributary of Turbid Creek. As the detached block accelerated, it quickly fragmented into an aggregate consisting of angular clasts up to several metres across, partially supported by a matrix of fine comminuted rock material. The landslide debris moved about 1 km down Dusty Creek as a wedge-shaped mass up to 70 m thick, banking up on turns and attaining a maximum velocity of 15–20 m/s. The debris mass thinned as it spread across the broader, flatter valley of Turbid Creek, and was deposited as an irregular blanket with a maximum thickness of 65 m along a 1 km length of this valley. As a result of the landslide, Turbid and Dusty Creeks were blocked, and lakes formed behind the debris. These debris dams were soon overtopped and rapidly breached, causing floods and probably debris flows to sweep down Turbid Creek valley far beyond the terminus of the landslide.From an analysis of the annual rings of slide-damaged trees, it is concluded that the landslide probably occurred in July 1963. Although the largest earthquake of 1963 and a moderately intense rainstorm also occurred during this month, there were much larger earthquakes and storms in this area on many previous occasions, and these did not cause large slope failures. Thus, it appears that the stability of the slope at the head of Dusty Creek gradually deteriorated over a long period of time until a relatively minor event, such as a small earthquake or storm, triggered the failure.The main contributing factors to this landslide are geologic and include the presence of: (1) hydrothermally altered faults and fractures in poorly lithified pyroclastic rocks and in jointed volcanic flows; (2) an outward-sloping unconformity separating the Quaternary volcanic sequence from older basement rocks; and (3) fractured glassy selvages surrounding small intrusions in the base of the volcanic pile.Deposits of one or more landslides that predate the 1963 event also occur in Turbid Creek valley. These older deposits are present over a much larger area than the 1963 slide deposits and probably were emplaced by highly mobile debris flows with high water content.



2013 ◽  
pp. 115-131
Author(s):  
Valeriy Klymov

Problems of interreligious relations at all levels - from interchurch to personal - accompanied religious communities throughout the history of their existence, gaining for various reasons the severity and urgency of the solution in some periods, and entering the channel of calm, everyday and business coexistence, into other . At one point in history, the antagonism of relations between religions and their representatives has repeatedly become the reason for the violent conversion of other peoples to their faith, the religious wars of several decades, large-scale manifestations of fanaticism, crusades, persecution of Jews, religious terrorism, etc.; in other historical secrets (no matter how short they were), tolerant relations between carriers of different confessions in multi-confessional societies created conditions for a coordinated solution of national problems, contributed to political understanding, mutually enriching coexistence of ethno-religious communities, ensuring the stability of societies and states



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