Deep below the surface of the Earth, a big glob of magma, some 2,000ºF, rises. It rises towards the surface, and it promises to make a spectacular eruption when it arrives. But it's not to be. The glob is cooling faster than it's rising, and it solidifies into an extremely hard chunk of granite before it reaches the surface.
All this happened more than 70 million years ago. Dinosaurs were walking around while this was going on.
In the space between then and now, weathering has steadily eroded the surface down. It erodes until it exposes the granite, then it keeps eroding. But the hard granite doesn't erode as quickly as the softer surrounding rock, so as the surrounding rock weathers away, the granite is left poking up here and there as monoliths to time and geology.
Sooner or later, some mammal with a penchant for naming things calls them 'Angel Rocks'.