Link to Tsvetana Paraskova. Headline says it all; details unimportant to me. Guess things happen that way.
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Book Recommendation
Again, if interested in origin of solar system, earth, fossil fuel, origin of life, this is currently the best new book on the market right now for armchair/amateur biologists, geologists, fossil fuel aficionados.
- How The Mountains Grew
- John Dvorak
- c. 2021
- Pegasus Books, August 2021
From the book, pages 131 - 133:
Eons, eras, and periods.
That's it. Three geologic "divisions": eons, eras, and periods.
With two exceptions, two "sub-periods":
- the Pennsylvanian (upper)
- the Mississippian (lower)
- The Brits sometimes (often?) refer to these as:
- the lower carboniferous;
- the upper carboniferous.
Let's take a look at coal:
- not evenly distributed around the world
- great abundance / vast majority of coal deposits are found in just five countries:
- India, China, Australia, and Russia: significant deposits; but,
- king of coal: the country with largest coal reserves: the United States
How did this come about:
- geologically there is a noticeable change from the deposition of limestone during the Mississippian subperiod to the deposition to coal;
- thus, a second subperiod has been created, the Pennsylvanian
- these are the only two subperiods in the geologic time scale
Introduction of the term cyclothem.
- layers of alternating strata:
- sandstone, formed upon a surface that had been cut by sea (saltwater) waves;
- then, a layer of silt, formed by the flow of freshwater;
- then coal;
- then repeating: sandstone, silt, and the coal again
- this pattern given a name: cyclothem
Many cyclothems have been named:
- the Dennis cyclothem: southwest of Dennis, KS
- the Plattsburg cyclothem: along a road cut west of Altoona, KS
- Wabaunsee cyclothem: at the side of I-70, west of Topeka, KS
- stretches for hundreds of miles from West Texas and across Kansas and Illinois and into the hills of Appalachia
So, if coal "came from" plant material, why is the distribution of coal so limited worldwide?
Mississippian subperiod:
- Eurameria -- the former Laurentia now enlarged by the additional of the continental bits of Baltica and Avalonia during the Devoniian Period -- straddled the equator;
- all other continental material had gathered and formed the large landmass of Gondwana,
- during the Pennsylvania subperiod, sat over the South Pole.
And, thus the reason why US is king of coal when it comes to coal reserves.