Question

In the eastern region of the former Soviet Union, a railroad was built on the tundra. The surface soil was dug up and tracks were laid down over the ground beneath. Within a year the ground shifted and buckled and the tracks could not be used. Using your understanding of the tundra, explain what probably happened.

Answer 1

When the surface layer was dug up, the permafrost was exposed. When the weather warmed, this exposed permafrost would have melted and become soggy, causing the ground underneath the tracks to shift.