The "White Giant” was caused by building water pressure in the lake that it extends across. Tourists huddled on a platform facing the glacier, located in the far south 78 kilometers (48 miles) from the town of El Calafate. Pieces of the glacier finally broke off late Monday night. "It was dark so we couldn't see it, but we heard it." Scientists say, that Perito Moreno, which is the world's only expanding glacier, spreads across a large swathe of southern Patagonia, ending in a translucent blue wall of ice along the Lago Argentino. Many of the world's glaciers are retreating