Plenty of both around my camp in northwestern Potter Denny. Every township road within five mils of my place was built by scraping the soil down to the underlying shale, doesn't take much scraping to reach it.
The logging roads are refreshed/improved after a sale by digging shale out of a bank and spreading it with a dozer.
On the other hand, there are plenty of stone quarries within a thirty mile radius where you can buy gravel.
IMO, gravel lasts much longer, shale breaks down/deteriorates much faster.
Should've said more common in my immediate area of the northern tier where camp is? There is some shale in our area, but pretty much everyone uses gravel on roads and driveways.
Never used to see much crushed limestone around there before gas operations started, now some of the twp. roads they've redone, were topped with modified limestone.
At least a half dozen former springtime "swamp holes" in the gravel roads were dug up and filled with crushed limestone in the past three or four years by gas company contractors.
And this summer limestone is everywhere on roads, driveways, etc.
They removed the "frack" pad at the well site down the road in August and all that limestone is now here, there and everywhere. It was pushed into a huge pile at one end of the pad free for the taking and the twp. boys have distributed it where needed.
Quite a bit went over the hill from camp, on the formerly mucky cemetery driveways. Many of my neighbors now have spiffy driveway entrances. Natcherly, no one thought to dump any in my camp driveway ruts.
Shale is hard clay. Many people thinks it compacts and makes good roads. It kind of does for awhile but than it breaks down and you have mud. It does work descent if you cover it with gravel sealing it. My local quarry has some material for 6.00 a ton that compacts well and can even be an under base for asphalt. Its a beter material to even work with machine or hand. I use shale at times on jobs but you never know what size you are going to get and can be apita.