The Huelmo–Mascardi Cold Reversal (HMCR) is a cooling event in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

between 11,400 and 10,200 ¹⁴C years BP. This cooling began about 550 years before the

Younger Dryas The Younger Dryas (YD, Greenland Stadial GS-1) was a period in Earth's geologic history that occurred circa 12,900 to 11,700 years Before Present (BP). It is primarily known for the sudden or "abrupt" cooling in the Northern Hemisphere, when the ...

cooling in the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...

, and both periods ended at about the same time. The event was given its name from the Huelmo,

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

, and Mascardi Lake,

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

( Nahuel Huapi National Park) sites where it was detected and dated. The HMCR cooling event began with the accentuation of a cooling period which began 12,400 ¹⁴C yr BP. The 11,400 ¹⁴C yr BP (13,400 calendar years BP) event onset took place 400–700 years before the onset of the Younger Dryas event. The 10,200 ¹⁴C yr BP (circa 11,500 cal yr BP) end date is difficult to calibrate to a calendar year because it took place during a radiocarbon age plateau. The end of the HMCR also marked the end of the cooling period.

References

* {{DEFAULTSORT:Huelmo Mascardi Cold Reversal Pleistocene History of climate variability and change History of South America