Marble Garden Zone (sometimes referred to as Marble Zone) is a region on Angel Island consisting mostly of trees and some ruins. It is also the location of the Grand Conservatory. Vector the Crocodile had previously lived on the outskirts of the Marble Garden Zone.
When the barriers between pocket zones began to break down as a result of the firing of the Ultimate Annihilator, the earthquakes caused by Echidnaopolis return and disappearance to Mobius Prime could be felt as far away as the Marble Garden Zone. In 3237 a Dingo Regime-run concentration camp was located in the Marble Garden Zone. It was also the dropsite where the Chaotix and Sonic the Hedgehog arrived at night during their trip to Angel Island to liberate Locke. (StH: #101, #138, KtE: #4)