The first two are old targets with their proximate coordinates, though I think these may be scrambled some so you might have to search around in the vicinity to find them.
The next is an old tire pile on the base. A person or persons unknown took the time to arrange these into a giant ring approximately 400' across and add the editorial comment, "ugly." Why the Marines would drag thousands of tires out to this particular spot in the desert remains a mystery.
Though not technically labyrinths these natural craters resonate with the concept of labyrinths and draw attention, especially as seen from above. You'll have to navigate down the screen from the coordinates - look for a black smudge and zoom in. If you look to the right, about 200 feet, you'll see another pile of tires. It looks like someone has started to partially mark out an even bigger circle.
This is the Amboy Crater which is accessible to the public. The second photo, above is a closeup of the interior. You can see that someone did create a simple labyrinth within, as well as a heart.
If you know of any other such examples of labyrinths or circles in the landscape, please share with us.