Several (many?) years ago I rode with some people in Alaska, touring and camping. I used some Schwalbe Marathon Dureme, which held up very well. However, although much of our route was paved, there was a section of The Denali Hiway that was gravel for ~100 miles or so. That ride was my first experience riding any distance on gravel. I had pumped my tires to about 60 psi. The gravel was 1"-2" in size, with car tire paths somewhat smoother than the middle and sides. At one point, I decided I liked the looks of the tire track just on the other side of the middle rubble, and I decided to gently swerve over and take that track. My wheels went out from under me and I slid, a slow crash, for 20 or 30 feet, coming to a rest on the drive side of the bike. I had road rash from my shins to my shoulders, but no punctures, no mechanical damage.

Looking back, a more pliable tire at a lower pressure would have been a better strategy. The tires I used had a paved road tread when a semi knobby tread would have been better. And lower pressure would have let the tires conform to the gravel.