The Most Boring Place on Earth…?There are times when the chaos of work and hectic day-to-day
The Most Boring Place on Earth…?There are times when the chaos of work and hectic day-to-day life makes me long for some place… quiet. Some restful environment where nothing ever ever happens…Possibly, the closest fit on Earth to this description can be found in the deepest depths of the oceans, the Abyssal Plains. And even there, the quietest of the quiet has to be the localities where sedimentation is dominated by biogenic deposits, that is, by ooze.The Abyssal Plains within the ocean make up 30% of the Earth’s surface. They are flat. They are flatter than a pancake, far flatter than Kansas, with slopes a mere 30cm/300 m. The flattest of the flat are covered by oceanic ooze. This ooze is formed from the remains of silicious-skeleton plankton that rain, slowly, onto the abyssal floors from the more lively zones of the ocean above. While most sea plankton and creatures have skeletal parts based on calcite, at depths starting at more than 4000m the temperature-pressure conditions are such that all calcite-based plankton and animal debris dissolves. Thus, we are left with silica-rich ooze, which lithifies to chert – since most of the creatures making up the chert are radiolaria (http://tinyurl.com/omrd5r6 ), these are often referred to as radiolarian chert, or mookaite. The rate of sedimentation for this ooze is so slow that just a millimeter, or at most several centimeters, accrue in a period of a thousand years.So here, in this view of radiolarian chert from the ancient Tethyan Ocean, each five centimeter layer took approximately 5000 years to be deposited. 5000 years – that’s about equivalent to the entire recorded history of mankind. Count how many layers are in this photo alone, and then multiply it by a section containing another kilometer of layers: it would take 60 million years to deposit a 600m thickness of this ooze, as is reported typical of abyssal sediments. That’s a lot of dead radiolaria! Yes, possibly the most boring environment on Earth.I’ve darkened the area around the photo to remind us that the abyssal environment is dark, absolutely dark. In fact, one could say that the Abyss is abysmally dark.Annie RImage: Mine, from our Jurassic cherts in Greece.http://phys.org/news/2013-11-feast-famine-abyssal-plain.htmlhttp://www.scienceandthesea.org/index.php?option=com_content&task=view&id=108&Itemid=10http://www.britannica.com/EBchecked/topic/2483/abyssal-plain -- source link
#geology#abyssall plain#ocean#floor#chert#tethys#sediment#water