The steep wall behind Tomok village on Samosir Island is part of a block of uplifted caldera-fill rocks. The entire 630 km² island, which now rises to 700 m above Lake Toba, is capped with lake-floor sediments that were deposited before the island was uplifted above lake level.

Photo by Tom Casadevall, 1987 (U.S. Geological Survey)

This image is made available as a Public Domain Work, but proper attribution is appreciated.

Keywords: caldera

Toba