The holes formed by huge blocks of glacier that have been burrowed into the ground are called kettle holes.

Here's how they form:

1. Glacial Deposition: As a glacier moves, it picks up and carries rocks and sediment. When the glacier melts, it deposits this material in a process called deposition.

2. Ice Blocks: Large chunks of ice can become embedded within the deposited material.

3. Melting: Over time, these ice blocks melt, leaving behind depressions in the ground.

4. Kettle Hole Formation: These depressions are known as kettle holes.

Kettle holes are often filled with water, forming lakes or ponds. They can also be dry, becoming fertile ground for plant life.