Drove it again, to clarify the surface is old pavement that they've ground the top layer off of and thus has lots of parallel grooves. My guess is they ground it to provide more winter traction for cars and to stop maintaining it.

Like the others have said, not gravel, more a paved road that they've seemed to decide never to repave so lots of loose rock on old pavement. You'll feel less likely to puncture on a gravel than road bike which could make one think it's more a gravel road. But it's just a rough ride, if I'm going to do all this climbing I'd much rather go to Kerr Gulch and be able to have a fun descent on a well paved road.

Nice road segment.

Fairly recently oiled. It's more like pavement than gravel. Still an enjoyable ride

Not actually gravel, ancient pavement, firm but broken in places