Search Twitter or Instagram for #thatdallasquarry. Or search YouTube for “McKinney cliff jumping.” It’s a strikingly beautiful spot just off Highway 380, near New Hope Road. It’s also on private property. But there’s plenty to enjoy online. Update: The owners of this quarry really, really, really want us to make it clear that the land is private property and that anyone who goes there is trespassing, which is illegal.