Scientists from Newcastle University, the University of Bristol’s Glaciology Centre, the British Antarctic Survey and the universities of Edinburgh, Exeter, and York recently discovered a trench beneath the ice in Antarctica and, well, it isn’t small. In fact, it’s huge – up to 3 kilometers deep, more than 300 kilometers long and up to 25 kilometers across.

According to Professor Martin Siegert, Professor of Geosciences at the University of Bristol, this is something of a watershed moment for scientists studying the Antarctic Ice Sheet. Though scientists have been aware of its cycles of growth and decay for decades, they’ve never been quite clear on a point of origin.

“By looking at the topography beneath the ice sheet using a combination of ice-penetrating radio-echo sounding and satellite imagery, we have revealed a region which possesses classic glacial geomorphic landforms, such as u-shaped valleys and cirques, that could only have been formed by a small ice cap, similar to those seen at present in the Canadian and Russian High Arctic. The region uncovered is, therefore, the site of ice sheet genesis in West Antarctica,” he said.

Rather than take to the ice with shovels and picks, the scientists spent three seasons mapping the area using data from satellites and ice-penetrating radar towed behind snowmobiles. In addition to the ancient subglacial trough, they also charted the mountain range known as the Ellsworth Subglacial Highlands.

The study offers an exceptional insight into the extent, thickness and behavior of this ancient icefield, and the configuration and behavior of the early West Antarctic Ice Sheet. The subglacial landscape reveals where and how the West Antarctic Ice Sheet originated and grew. It also offers important clues about the size and shape of the ice sheet in West Antarctica in a warmer global climate.

However, Dr. Neil Ross from Newcastle University notes that there’s much more work to be done if we hope to broaden our understanding of the continent.