{"id":1561,"date":"2015-10-26T22:38:17","date_gmt":"2015-10-26T22:38:17","guid":{"rendered":"http:\/\/all-geo.org\/volcan01010\/?p=1561"},"modified":"2015-11-02T21:39:27","modified_gmt":"2015-11-02T21:39:27","slug":"a-sedimentologists-guide-to-volcanic-particle-grain-size-and-foetal-development","status":"publish","type":"post","link":"https:\/\/all-geo.org\/volcan01010\/2015\/10\/a-sedimentologists-guide-to-volcanic-particle-grain-size-and-foetal-development\/","title":{"rendered":"A sedimentologist’s guide to volcanic particle grain size (and foetal development)"},"content":{"rendered":"

volcan01010<\/strong> is taking part in Paige Brown Jarreau’s<\/a> #SciBlogReaders study.\u00a0 It aims to understand why people read science blogs.\u00a0 If you have a few minutes spare between now and Halloween, please take the survey.\u00a0 The results will help understand science blogging and to improve volcan01010.\u00a0 Also, you’ll get free science pictures and a chance to win a t-shirt or a $50 Amazon.com gift card! You can find the survey here:\u00a0http:\/\/bit.ly\/mysciblogreaders<\/a><\/b>.<\/p><\/blockquote>\n

Volcanology has a lot of jargon.\u00a0 This can obscure simple information, even from trained geologists.\u00a0 Students are often put off by words like lapilli<\/em> or tephra<\/em> that sound terribly technical, even though they only mean little stones<\/em> (in Latin) and ashes<\/em> (in Greek).\u00a0 For this reason, I find it helpful to ignore the volcanology part and just treat the deposits as you would any other sedimentary rock.\u00a0 After all, studying explosive eruptions is just sedimentology in the atmosphere, and a volcanologist’s lapilli tuff<\/em> is simply a breccia<\/em> to any other geologist.<\/p>\n

Pregnancy books are obsessed with fruit and vegetables, which are compared to the size of the growing foetus in week by week guides to development.\u00a0 Such comparisons are helpful to people who have never seen a ruler.\u00a0 They are no substitute for real numbers, though.\u00a0 Is a kumquat bigger than a fig?\u00a0 I have no idea.\u00a0 Nevertheless, they are fun to visualise.<\/p>\n

For these reasons, I have compiled the following table that compares the size of volcanic particles, sediment grains, fruit and growing foetuses.\u00a0 I hope that it will go some way towards demystifying volcanology to sedimentologists, and gynaecology to gardeners.<\/p>\n

Comparison of volcanic and sedimentary grains, and fruit and foetuses<\/h3>\n
\"volcano_sediment_fruit_foetus_600\"<\/a>

Click to enlarge.<\/p><\/div>\n

Using this table, you can imagine volcanic processes in a whole new way. For example, a block and ash flow caused by a collapsing lava dome<\/a> can be imagined as a hot fruit salad, containing everything from poppy seeds to (whole) pumpkins, thundering down the side of the volcano.\u00a0 There is also the question of the size of grains in a volcanic ash cloud<\/a>;\u00a0 aircraft that sampled Icelandic examples them found grains about the size of sperm-heads, while the grains that are found on the ground can be two sperm long.<\/p>\n

Further reading<\/h3>\n