{"id":32469,"date":"2019-10-23T06:36:16","date_gmt":"2019-10-23T06:36:16","guid":{"rendered":"https:\/\/blogs.agu.org\/landslideblog\/?p=32469"},"modified":"2019-10-23T06:36:16","modified_gmt":"2019-10-23T06:36:16","slug":"wood-1","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2019\/10\/23\/wood-1\/","title":{"rendered":"The role of landslide dams in depositing carbon in marine sediments"},"content":{"rendered":"
\"Wood\"

Catastrophic landslides are an effective way to transport wood from the land to the deep ocean.<\/p><\/div>\n

The role of landslide dams in depositing carbon in marine sediments<\/h4>\n

As concern grows about the threats of global heating, there is increased interest in understanding how, when and how much carbon is stored in the oceans.\u00a0 One mechanism is the transport of wood from uprooted trees through the river system and out to sea.\u00a0 This may be a key pathway through which carbon is stored, and thus understanding the mechanisms through which this can occur is important.<\/p>\n

In a paper just published in PNAS<\/a>, (Lee et al.<\/em> 2019<\/a>), a team has looked at cores drilled into the Bengal Fan, the largest sedimentary deposit on Earth, which stretches 2,000 km from the mouth of the Ganges River.\u00a0 They have been particularly interested in the presence of wood in these marine deposits.\u00a0 The results are intriguing – the team found very distinct woody layers in the sediments, even in those drilled in 3,700 m water depth, at distances of hundreds of kilometres from land.\u00a0 Perhaps most interestingly, they found one layer, dated to about 50,000 years ago, that contained abundant pristine pieces of conifer, which typically grow at about 3 km above sea level.\u00a0 The implication is that large volumes of wood are able to travel in concentrated pulses from high in the mountains out to the deep ocean.\u00a0 This raises a question as to how this can occur.<\/p>\n

Lee et al.<\/em> (2019<\/a>) propose that the most likely mechanism is very high discharge events – i.e. catastrophic floods that carry large volumes of woody material in a single pulse.\u00a0 The authors propose that the most likely cause of such floods would be the collapse of either landslide or glacial dams.\u00a0 An article on Eurkalert<\/a>, informed by one of the researchers, Dr Sarah Feakins<\/a> (associate professor of Earth sciences at USC Dornsife College of Letters, Arts and Sciences) described how this might happen:<\/p>\n

The trees likely were uprooted during the last ice age by a massive release of water from the breach of a natural dam created by a glacier, landslide or similar land feature. In what must have been a surge of water, the trees rode rivers thousands of miles from Nepal through Bangladesh and into the Bengal Fan.<\/em><\/p>\n

We know that these large, catastrophic events are critically important in creating the landscapes in active mountain chains<\/a>.\u00a0 The discovery that these extreme events are also important in the ways in which the carbon cycle operates is now becoming clear.\u00a0 Landslides generated by a large earthquake release vast numbers of trees from the hillsides.\u00a0 Very often this wood is then trapped behind landslides dams.\u00a0 The breaching of these dams provides a mechanism through which that wood can transported out to the deep ocean, and buried on the sea floor.<\/p>\n

Reference<\/p>\n

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Hyejung<\/span> Lee<\/span><\/span>, Valier<\/span> Galy<\/span><\/span>, Xiaojuan<\/span> Feng<\/span><\/span>, Camilo<\/span> Ponton<\/span><\/span>, Albert<\/span> Galy<\/span><\/span>, Christian<\/span> France-Lanord<\/span><\/span>, Sarah J.<\/span> Feakins 2019.\u00a0 Sustained wood burial in the Bengal Fan over the last 19 My<\/a>.\u00a0 <\/span><\/span><\/span>Proceedings of the National Academy of Sciences<\/span><\/em>, <\/span>201913714; <\/span>DOI:<\/span> 10.1073\/pnas.1913714116.<\/span><\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

Floods from valley-blocking landslides may play a key role in the carbon cycle, allowing wood to be transported from the high mountains to the deep ocean floor<\/p>\n","protected":false},"author":22,"featured_media":32470,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[608],"tags":[27864,71,469,25902,192,17],"class_list":["post-32469","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-research-project","tag-carbon","tag-dam","tag-featured","tag-global-heating","tag-paper","tag-research"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/32469","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/users\/22"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/comments?post=32469"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/32469\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/32470"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=32469"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=32469"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=32469"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}