The Drake – February 19, 2020
By the time this Science Wednesday posts, I will have crossed the Drake Passage three times, working aboard the Greg Mortimer polar class expedition cruise vessel with Aurora Expeditions. The Drake Passage is a treacherous stretch of water that formed when the “arm” that once connected South America and Antarctica eroded away. Before the passage opened, the Atlantic and Pacific Oceans were separate, Antarctica was much warmer, and there was no ice cap.
Its name? It comes from the English sea captain, Sir Francis Drake, who circumnavigated the globe in the 16th century. In September 1578, his only remaining ship was blown far south after passing through the Strait of Magellan, implying that there was an ocean south of South America. However, the first recorded voyage through the passage wasn’t until 1616, by Dutch navigator, Willem Schouten.
So, when did the Drake Passage actually open up, as for the longest time, this was a topic of scientific debate? It turns out the answer lies in fossils: fish teeth, in particular, that were recovered from the bottom of the Atlantic Ocean. The chemical signature in these teeth captured the chemistry of the oceans (the Atlantic and Pacific differ), allowing scientists to determine when Pacific waters started “seeping” into the Atlantic. It turns out that scientists can finally put a firmer date on it: 41 million years ago. A few million years later, build-up of the ice cap on Antarctica started. The formation of the ocean current that circulates around the continent (the Antarctic Circumpolar Current) played a key role in the cooling of the land, as the current deflects warm streams of water coming from the equator.
*The photo is from when I worked aboard the Nathaniel B. Palmer icebreaker in Antarctica, 2007.