Monday, February 1, 2012

L7 - Alternate

F1

1Recap of Milankovitch Cycle¶

1.1Lots of players - need to know people in detail¶

1.2Need to know…¶

• who they were
• who their supporter were
• who naysayers were

2Revival of the Milankovitch Cycles¶

-- sea terraces show former coastlines (new guinea)
-- Thorium dating was important
-- wallace beckoner dated acient fossil reefs (florida keys, bahammas)
-- -- Found dates of 120-180,000 years
-- -- aligned well with Milaknovitch's 45 degree
-- Around the same time, a professor called Mathews from Brown found terraces. sent them to Brecker to date them - Brecker dated the terraces to 125,000 years ago
-- the curves from the lower latttidue were influenced more by the something which showed a clear match with the barbados terraces - 82, 105, 125
-- but researchers wanted a geologic date

31906 Brickyards¶

-- when bricks cool, they align with magnetic fields
-- ancient lava flows showed a reversal in the earth's magnetic fields
-- matormy matyaymo reached the same conclusion
-- in labs, some minerals could reverse themselves
-- from book, "in spite of the fact that the minerals of capable of self reversal, whirr rare in lava's, almost all the scientists questioned about self reverals than the revolutionary idea that the earth could reverse itself"
-- research around the world came up with the same conclusions, that earth field reversed itself
-- this gives a date

4paleomagnetic correlations¶

-- the magnetic reversal is what enabled scientists to come up with a date for the "pliesticy" (we're in the Scienzoik, to epochs, we're in the holocene)
-- need to determine the length of the plisticene
-- they go back to cores and look at the line where the fields reverse - this was dated to 1.8 million years ago

5george cookla¶

-- studied "loess" - wind blown sediment
-- derived from streams coming out of the something
-- rivers dry, sediment is blown - the breadbasket of usa is from this great soil for farming
-- cockle builds a trech at a quarry -
-- finds 5 magnetic reversals
-- they believed that the 'eccentricity aspet of the theory is a good match for the cycle, is indirectly responsible'
-- earth elliptical - lots of variation in procession
-- cockle is with croll, answer is in winter
-- grad student, like milkanovitch, says answer is in summer

61970 - climate project¶

-- john hayes and imbrie
-- 2 main goals - 1) map earths surface over last ice age and 2) to measure plitoscene oscillations
-- 3 results: 1) climate oscillations occur as 4 distinct cycles: a 100,000 yr cycle for eccentritcy, 41,000 cycle for axis tilt, and 2 procession cycles of 23,000 and 19,000 years
-- imprie showed that the ice sheets lagged 8,000 years behind the axial tilt
-- for the procession cycle, there was a lag time of systematically behind (i.e. like 25% of the procession cycle)
-- published "variations in the earth's orbit - pace makers for the earth climate" in Science