Galvanize is an English word derived from the last name of Frenchman Luigi Galvani who discovered the muscles of dead frogs twitched when stimulated with electricity. He did not invent the galvanization coating process. The word has two meanings. 1) Shock or excite someone, typically into taking action. 2) Coat iron or steel with a protective layer of zinc by dipping the metal into a bath of molten zinc. The zinc reacts with oxygen to form zinc oxide which reacts with carbon dioxide to form zinc carbonate which resists further corrosion and protects the steel it coats from the elements. Galvanized steel is widely used in applications where corrosion protection is needed at a lower cost than stainless steel. Even if the coating is damaged, the zinc will corrode faster than the steel.
If you look around you, you will see there is also a lot of galvanized metal used in this area of the Greenbelt. I do not know why the designers chose galvanized coatings over other pigmented coatings or other metals than iron/steel, but I am sure they had reasons. I do not care for the look of galvanized products in a recreation area and will avoid using them, but there are those who just love to look at galvanized coatings.
The cache is not galvanized. The cache is a couple steps off the Greenbelt path. No bushwacking required.