Closest to Arches - the Uinta Basin is north of there, but quite a ways north. The richest ail shale is the eastern part of the basin that extends into Colorado. The Green River formation is in the area where Utah, Wyoming and Colorado come together and that's where the oil shale and oil sands are concentrated. The dotted line area in Utah below is roughly the Uinta Basin. I assume you know where the parks are.
