Why go
Understanding the process changes what you see from the glacier viewpoints. Ice advancing across the channel can separate Brazo Rico from the main lake. Rising water then pushes through the barrier, sometimes leaving an arch before it collapses. Even outside a rupture, the glacier and shoreline show the forces at work.
The full story
Perito Moreno Glacier sometimes advances far enough to close the narrow passage between its front and the opposite shore. This creates a natural ice dam between Brazo Rico, an arm of Lake Argentino, and the lake's main body. Water continues to feed the blocked arm, so its level can rise above the water on the other side. Pressure eventually opens a passage beneath or through the ice. An arch may form, then fail as water and ice move through the gap. This is the rupture for which the glacier is famous. The sequence has repeated at irregular intervals, which means a past event cannot predict the date of the next one. The difference in water level can leave a visible mark on the shore after the release. From the viewing area, the useful thing to notice is the meeting of glacier, land and water: that narrow geography makes the whole process possible.
Useful to know
- Plan for glacier viewing rather than a predicted rupture; the timing varies.