Tuesday, September 08, 2015

Geosonnet 32

Southwest from where Doc Livingstone was found
The grand conglomerate caps old black shales.
The rhenium, in micro-pyrite bound,
Can date when diamictite ice prevails.
The wild’s call, beyond the Yukon Gold
Hides ancient glaciation in the wilds.
To test the Snowball Earth, we ask, “How old”
These jigsaw continents, frozen or mild?
Just past the pleasure dome of Kublai Khan
Mongolia preserves more ancient rock
The age determination’s not forgone
We must assess the isotopic clock.
   For fifty million years, and then for five,
   The planet froze, yet somehow stayed alive.

Other geosonnets: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47


Chris Phoenix said...

"Somehow stayed alive" - I wouldn't expect Snowball Earth to have had much impact on undersea "black smokers" or the chemosynths that lived on them.

Whether the ancestors of animals, kelp, algae, etc. could all survive in a chemical-based food chain rather than a sun-based food chain is another question.

http://www.snowballearth.org/life.html describes some interesting simulations showing that a totally-covered Earth could have regions of thin ice, regions of recently-formed ice with brine channels, and un-iced land areas which (along with volcanoes) could have contributed dust to surface-living microbes (snow algae is a thing today).

C W Magee said...

Ye et al. (Geology 43 559) is in the queue, and will address that very issue. Read the paper, or wait for the sonnet.

C W Magee said...

The Ye et al. sonnet is up at #36: http://lablemminglounge.blogspot.com.au/2016/01/when-sand-dunes-glacers-spread-across.html