‘Break Down’ of Ocean Cooling System


From October through the end of December 2006, high-tech drills penetrated to a depth of exactly 1,287.87 meters (4,225.3 feet) into the Ross Ice Shelf in the eastern Antarctic. The sediments that were brought to the surface with the drill core allow researchers to embark on a voyage back in time.

For every meter (about 3 feet) of sediment, scientists can now peer about 10,000 years into the past. The recent drilling effort offers scientists a look at what may have happened on the earth up to about 12 million years ago.

The sample could prove to be one of the most important drill cores in recent years. The sediments it contains show that the Antarctic climate has only been continuously cold for about the last million years, during which one of its largest bays has been constantly covered by a layer of ice up to several hundred meters thick.

The ice shelf melted about 5 million years ago and, presumably along with it, a significant portion of the ice on land. Where researchers must now drill through 80 meters (262 feet) of the ice shelf before reaching the sea floor at a depth of 800 meters (2,625 feet) was once open sea. The earth’s climate fluctuated constantly in the ensuing 3.5 million years.

Those are the early conclusions drawn by geologists at Andrill (Antarctic Geological Drilling), the multinational consortium leading the project, which recently released preliminary data from the drilling on its Web site. With the joint project, which is being conducted by Germany, Italy, New Zealand and the United States, scientists hope to reconstruct the prehistory of Antarctic environmental conditions using new drill cores.

This is more difficult than it sounds, because glaciers and icebergs have churned up the sea floor in many locations near the coastline. Further complicating matters, scientists often find little more than the rock debris of end moraines in the bottom portions of the drill core. But in late 2006, the Andrill team discovered undisturbed deposits 15 kilometers (9 miles) outside the research station near the Mount Erebus volcano.

A first look at conditions that prevailed five million years ago

“This time we were able to drill into layers representing the period between five and 12 million years ago,” Andrill team member and geologist Lothar Viereck-G