“The Svartisen glacier in Norway is one of the few places on earth where ice can really be seen in action… not just from the outside, but from the inside. Deep beneath the glacier, in a chamber at the end, scientists come face to face with ice. Then it’s two days of hard work using hot water to melt a cave big enough to get inside the glacier and see it in all its glory.”

Follow glaciologist Miriam Jackson into the shrinking human-made ice cave at the bottom of Svartisen glacier. There, she shares two discoveries that reinforce why and how these immense, ever-moving glaciers are so powerful.

Discovery one: Below the pure basal ice is dirty, residue-filled ice. From bits of gravel to large rocks, sediment is captured and carried with the frozen mass.

“‘They’re also just rubbing along at the bottom of the glacier, it’s like sandpaper just wearing away, wearing away at the rock underneath.’ So it’s not the ice itself that does all of the damage. It’s the debris that it picks up along the way… ‘It can carry absolutely huge pieces of rock along with it and transport them down the valley.'”

Discover two: Water pockets in the ice, a surprise that “may help explain why something as apparently solid as ice can also bend and flow… ‘Just the presence of these holes in the ice with water, it does make the ice softer and it makes it flow more easily.'”