Nazca

History

The past. At the ice age peak, about 20,000 years ago, the sea stood about 125 metres lower and the Galápagos were about half again as big as they are now; the rising sea drowned that land, mostly between 19,000 and 9,000 years ago, and split larger islands into smaller ones. The cold Peru Current carried cold-water plankton as far north as the equator, but no ice sheet or sea ice reached the plate: the Patagonian ice sheet stopped on the Chilean shelf, some 40 kilometres short of it, and the winter sea ice stayed about 1,600 kilometres to the south. The drowned island edges were less than a tenth of one percent of the plate, too little to change its colours.

56.2 million years ago

The oldest ocean floor on this plate formed, on the older Farallon plate.

30 million years ago

A hotspot was already building the line of seamounts and the ridge that now cross this plate.

23 million years ago

The Farallon plate split in two, and its southern part became this plate.

Sources: Lambeck et al. 2014, PNAS 111:15296; Geist et al. 2014, AGU Geophysical Monograph Series p. 145; Feldberg and Mix 2003, Paleoceanography 18; Davies et al. 2020, Earth-Science Reviews 204:103152; Lhardy et al. 2021, Climate of the Past 17:1139 · Seton et al. 2020, age grid v2020.1 processed here, Geochemistry Geophysics Geosystems · Ray et al. 2012, Journal of Petrology 53:1417 · Lonsdale 2005, Tectonophysics 404:237