Inside a glacier - Earth - The Power of the Planet - BBC

Summary

In a fascinating exploration beneath a glacier, scientists use hot water to carve out an ice cave, uncovering the dynamic behavior of ice. Glaciologist Miriam Jackson describes how ice, despite seeming solid, can bend and flow, aided by water pockets that soften the ice, making it more pliable. As the glacier moves, it carries massive rocks, with debris eroding the underlying rock like sandpaper. The ice cave, though beautiful, is ephemeral, disappearing in just three days. This expedition reveals the powerful, yet delicate, nature of glaciers and their surprising ability to reshape the landscape.

Takeaways

• 😀 Scientists are working beneath a glacier in a chamber 200 meters below the surface, with the glacier continuously closing in on them.
• 😀 Glaciologist Miriam Jackson spends up to three weeks at a time working in this challenging environment.
• 😀 The team uses hot water to melt a cave large enough to explore inside the glacier.
• 😀 The bottom of the glacier contains both pure ice and dirty ice that picks up sediment and rocks as it moves.
• 😀 It's the debris carried by the glacier, rather than the ice itself, that causes most of the damage to the bedrock below.
• 😀 Glaciers can transport large rocks, up to the size of a house, along their path, showcasing their immense power.
• 😀 A key discovery in the glacier was the presence of water pockets at the base, which is unusual for glaciers.
• 😀 These water pockets are not well studied, and their existence at the glacier's base was a surprising finding.
• 😀 The water pockets make the ice softer, allowing it to bend and flow more easily around obstacles.
• 😀 The discovery of water pockets helps explain why ice, which seems solid, can actually flow and bend rather than break.
• 😀 After just three days, the ice cave created by the team disappears as the glacier continues to shift and move.

Q & A

What is the primary challenge scientists face while working in the glacier cave?

The primary challenge is the constant closing in of the glacier, which forces scientists to work quickly before the ice blocks their access. They must complete their tasks within a limited timeframe before the glacier completely seals off the cave.

How does the glacier affect the rocks it comes into contact with?

As the glacier moves, it picks up debris such as gravel and rocks, which scrape and rub against the solid rock underneath. This process acts like sandpaper, slowly wearing away at the rock and contributing to the glacier's ability to carve through the landscape.

What makes the ice at the base of the glacier appear different from the rest of the glacier?

The ice at the very bottom of the glacier is mixed with sediment and debris, making it appear dirty compared to the clean ice above. This is because the glacier picks up various materials as it moves, and these materials become embedded in the ice.

What role do water pockets play in the glacier's movement?

Water pockets at the bottom of the glacier help to make the ice softer and more flexible. These pockets reduce the brittleness of the ice, allowing it to bend around obstacles and flow more easily across the landscape.

Why are water pockets in glaciers considered an important discovery?

Water pockets are significant because they were previously unknown and help explain how glaciers can flow despite appearing solid and rigid. Their presence makes the ice less brittle and more capable of bending and flowing.

What was the initial reaction of scientists to finding water pockets in the ice?

Scientists were surprised to find the water pockets, as they had not been observed or studied in this context before. This discovery challenged previous understanding of how glaciers behave and function.

How large can the rocks carried by the glacier be?

The glacier can carry rocks that range in size from smaller pebbles to much larger boulders, with some rocks being as large as a meter across. In other glaciers, rocks can be as large as a house.

How do glaciers move and change over time?

Glaciers move by picking up debris and slowly carving through rock. The ice at the base of the glacier, combined with the debris it carries, allows the glacier to flow and change over time. The ice cave itself can disappear in just a few days, highlighting the glacier's dynamic nature.

What does the temporary nature of the ice cave illustrate about glaciers?

The ice cave's brief existence, disappearing in just three days, illustrates the ever-changing and transient nature of glaciers. Their internal dynamics constantly reshape the environment, making them highly impermanent.

How does the presence of debris in the glacier's ice contribute to its ability to shape the landscape?

The debris embedded in the glacier acts like a tool for erosion. As the glacier moves, it rubs this debris against the underlying rock, grinding it down and shaping the landscape. This process allows glaciers to carve valleys and modify their environment over time.