1867 to 1903 my town was owned by a timber baron. His crews stripped 30,000 acres in my town 100,000 in several other towns. What didn't sell as lumber was burned for potash & charcoal. Griffith's roads crossed a lot of swamps, & wet spots. Everything was corduroyed. Typically, 3 to 5" diameter sapling trunks were used. Where they stay wet all the time, a few can still be found. Wood rots very slowly where saturated in cold water. We had a beaver dam fail a few years ago washed out a steel culvert. Beneath it, a four log culvert was exposed. It was intact after 140 years.
They used logs for cribbing, building wagon roads across the sheer stone face of the mountain. I can't say how long untreated logs lasted holding up a road.