Zeta Point is the Alpha Gang's base of operations and hideout. The name of Zeta Point is a pun on Alpha Gang, as both of them are from the Greek Alphabet (however, Omega is the last Greek letter in their alphabet, not Zeta, although Zeta corresponds with 'Z', the last letter of the English alphabet). Zeta Point is an artificial island that moves around (when it's working, as it wasn't until episode 13), causing earthquake-like movement. Even though Zeta Point wasn't a real island, it made a great playground for Terry and his friends in their chibi forms.
Zeta Point is first discovered in Dinosaur King episode 12, when the D-Team go there after Ceratosaurus activated there. After they discover that it was the Alpha Gang's lair, they are quickly defeated and caught. However, they manage to break out and escape in the next episode, thanks to Reese and Dr. Taylor.
The island part of Zeta Point is only a disguise intended for camouflage. It's true form is the Backlander. The tall spiral tower seen atop Zeta Point is the only part of the Backlander visible when it's disguised as the island.