Some people say that some Atlanteans would have migrated to the center of the Earth before the strong catastrophic event that tilted the Earth's axis a few degrees. Event caused by experiments with telluric forces. And there is another race living in a shallower potion, less evolved beings living in caves as you say. When someone see flying saucers (which are multidimensional) fading behind the mountain, these objects are actually traversing into it for these deep locations. But we have no way of knowing what is true, especially if have interest of governments. I'll research about Corey Goode, it's a very interesting subject. Thank you.