Due to difficult terrain human labor is the main driving force of work done.

This is because of the very difficult terrain and the large altitude difference.

In the difficult terrain, the French soldiers might have an advantage.

He said that the costs included the rolling stock, and the line passed through some of the most difficult terrain in the country.

It can travel at around sixty miles per hour over difficult terrain.

There is a new site planned to the north, with difficult terrain.

In recent years, it has had to deal with a much more difficult terrain.

Also, it has difficult terrain and not many plants or water sources.

This difficult terrain was the only reason the owners of the land did not use it.

The only road to the mine was over difficult, rocky terrain.