TIMES JABAR, JAKARTA – Nestled in the easternmost part of Java Island, Watu Dodol Beach in Banyuwangi is a site of significant geological interest. The beach is renowned for its ancient volcanic remains, dating back approximately 30 million years. This region, recognized as part of the UNESCO Global Geopark (UGG), is a treasure trove of geological wonders and historical insights.

The primary geological feature of Watu Dodol Beach is the presence of Pillow Lava Rock, a key indicator of ancient volcanic activity. Pillow Lava Rock forms when lava erupts underwater, creating pillow-shaped structures as the lava cools rapidly upon contact with the ocean.

According to Abdillah Baraas, General Manager of Geopark Ijen, this phenomenon suggests that the area once hosted an underwater volcano. It is similar in age to Krakatau, which erupted around 25-35 million years ago.

The beach's basaltic lava flow deposits are visible, with a composition containing approximately 20% quartz. These deposits provide a dark, rugged appearance, consistent with the volcanic rock types found in the southern part of Banyuwangi. The morphological features of Watu Dodol Beach include a narrow coastline with a dramatic elevation change compared to the surrounding hills.

To the north of Watu Dodol Beach, the landscape reveals limestone formations intermingled with the Pillow Lava Rock. During low tide, the exposed rocks display fragmented, pillow-like structures, evidencing the lava's movement from the shore into the sea. Some of these lava formations appear bulbous or rope-like, reflecting the dynamic nature of ancient volcanic eruptions.

The surrounding limestone originated from ancient coral reefs that were deposited and uplifted through tectonic movements, which also contributed to the exposure of the Pillow Lava Rock. Fossils of shallow marine organisms found within these limestone formations indicate that this region was once covered by a shallow sea.

In addition to Watu Dodol Beach, remnants of ancient volcanoes can also be found at Parang Ireng Beach, another site of volcanic significance in the area. Research conducted by Professor Benyamin Sapiie, a noted tectonic expert from ITB, has further explored the implications of these ancient lava formations and associated liquefaction events in Banyuwangi.

Watu Dodol Beach, with its rich geological history and ideal location for witnessing the first sunrise in Java, serves as a natural laboratory for studying the structures and processes associated with ancient volcanic eruptions. Its unique features make it an invaluable site for both scientific research and geological tourism. (*)