Just another piece in/for the puzzle

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parfive no longer being taken for granite Member since August 2005 Posts: 9,620	Just another piece in/for the puzzle Jul 11, 2018 22:21:17 GMT -5 Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by parfive on Jul 11, 2018 22:21:17 GMT -5 Earliest evidence of humans outside Africa www.bbc.com/news/science-environment-44797323
	Consider the Earth’s history as the old measure of the English yard, the distance from the King’s nose to the tip of his outstretched hand. One stroke of a nail file on his middle finger erases human history. John McPhee - Basin and Range

parfive
no longer being taken for granite

Member since August 2005
Posts: 9,620

Just another piece in/for the puzzle Jul 12, 2018 2:10:00 GMT -5

Quote

Post by parfive on Jul 12, 2018 2:10:00 GMT -5

More thorough article and a pic or two . . .

www.nytimes.com/2018/07/11/science/hominins-tools-china.html

Also gets into that magnetic field flippage discussed here recently.

To determine the age of the tools, the researchers took advantage of the planet’s changing magnetic field.

From time to time, Earth’s magnetic field flips, turning north to south. Magnetic minerals in the soil and ocean are pushed into alignment with the field; when they are trapped in rocks, they still point in the telltale direction.

Geophysicists have precisely determined the timing of these magnetic flips, which have taken place at the same time all around the world. It’s a useful way to date the material found in layers of rock.

The layers in the gully formed over many hundreds of thousands of years. And the oldest tools were neatly sandwiched between rocks that formed between two flips of the magnetic field: one 2.14 million years ago, and a second about 1.85 million years ago.

Consider the Earth’s history as the old measure of the English yard,
the distance from the King’s nose to the tip of his outstretched hand.
One stroke of a nail file on his middle finger
erases human history.

John McPhee - Basin and Range

grumpybill
freely admits to licking rocks

Member since June 2017
Posts: 940

Just another piece in/for the puzzle Jul 12, 2018 19:27:22 GMT -5

Quote

Post by grumpybill on Jul 12, 2018 19:27:22 GMT -5

… these magnetic flips, which have taken place at the same time all around the world...

Really?

When the magnetic poles flip, they flip all around the world? who'da thunk it?
You'd think journalists would have at least an elementary understanding of their subject.

I changed my mind yesterday. The new one doesn't work any better than the old one.

grumpybill freely admits to licking rocks Member since June 2017 Posts: 940	Just another piece in/for the puzzle Jul 12, 2018 19:34:13 GMT -5 1dave likes this Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by grumpybill on Jul 12, 2018 19:34:13 GMT -5 Makes one wonder if the "out of Africa" theory is correct. It could be coincidence that the earliest hominid evidence has been found there.
	I changed my mind yesterday. The new one doesn't work any better than the old one.

parfive
no longer being taken for granite

Member since August 2005
Posts: 9,620

Just another piece in/for the puzzle Jul 12, 2018 21:22:24 GMT -5

Quote

Post by parfive on Jul 12, 2018 21:22:24 GMT -5

Ain’t that simple.

Scientists estimate that past polar flips have been rather sluggish, with north and south migrating to opposite positions over thousands of years.

They've also learned what happens during a magnetic flip. Reversals take a few thousand years to complete, and during that time--contrary to popular belief--the magnetic field does not vanish. "It just gets more complicated," says Glatzmaier. Magnetic lines of force near Earth's surface become twisted and tangled, and magnetic poles pop up in unaccustomed places. A south magnetic pole might emerge over Africa, for instance, or a north pole over Tahiti. Weird. But it's still a planetary magnetic field, and it still protects us from space radiation and solar storms.

A reversal happens over hundreds or thousands of years, and it is not exactly a clean back flip. Magnetic fields morph and push and pull at one another, with multiple poles emerging at odd latitudes throughout the process.

news.nationalgeographic.com/2018/01/earth-magnetic-field-flip-north-south-poles-science/

Check the last illustration . . .
science.nasa.gov/science-news/science-at-nasa/2003/29dec_magneticfield/

www.nasa.gov/topics/earth/features/2012-poleReversal.html

More from Glatzmaier . . .
cs.astronomy.com/asy/b/astronomy/archive/2017/12/27/is-the-earth-s-magnetic-field-due-for-a-pole-reversal.aspx

grumpybill freely admits to licking rocks Member since June 2017 Posts: 940	Just another piece in/for the puzzle Jul 13, 2018 6:01:20 GMT -5 1dave likes this Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by grumpybill on Jul 13, 2018 6:01:20 GMT -5 Yep. I know that during transition, the poles can appear anywhere around the world. I was criticizing the NYT writer for stating the obvious: That the shifts effected the whole planet.
	I changed my mind yesterday. The new one doesn't work any better than the old one.

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