“Vertical ice caves in Greenland, called ‘moulins,’ drain water from the ice to the sea — and they’re even bigger than we thought”
“The scientists prepped for their descent into the maw of the Greenland ice sheet by drilling deep into the ice. They created two intersecting holes into the bed of a now frozen-over ice river, running a rope through them in the shape of a V to anchor their lines. It would be more than strong enough to carry their weight, but they drilled a second anchor as well — just in case.
Then Matt Covington, a geologist and cave explorer who has spent more than a year of his life beneath the ground, was ready. He began to lower himself into the vertical cavern that, in the summer, fills with the chaos of a waterfall — a moulin. The sharp crampons on his boots gripped the ice. The fact that it was October now made the moulin a little safer, but Covington could still hear running water somewhere.
Below him, as he backed over the edge and looked down the shaft, he saw white ice, then bluer ice, then darkness. The hole, scientists believe, ultimately penetrates more than a half-kilometer into the ice, joining a network of channels extending all the way to the base of the ice sheet.”