The limestone mountains in Tuban are a stunning landscape. Tuban a city in the north of East Java has an interesting geological history. However, it’s not because of volcanic activity. It’s more of the limestone mountains around Tuban. In the past Tuban only had a small industry. Agriculture dominates the landscape around the town. But today, because of the settled industry Tuban turned into an industrial centre. One reason for this process is the huge limestone deposit.
Long time I thought that the mountains are a result of volcanic activities in this area. Because Indonesia is part of the ring of fire. The amount of volcanos is one of the highest in the world. However, the limestone mountains are definitively not a result of volcanic activities. In fact, the limestone mountains are coral reefs. When millions of years ago the Java sea level dropped the reefs came out of the sea to the surface. These lifted reefs shape the landscape around Tuban today.
The limestone mountains are old coral reefs. Composed mainly of skeletal fragments of marine organisms such as corals, shells or sponges.
Most of the limestone is used in the nearby cement factories. Limestone is also used as filling material for construction works or as bricks for houses. Besides the big factories, there are also smaller businesses. For instance, where workers burn the limestone to quicklime. The limestone business is a huge industry. So far, luckily many people have a job there.
Visiting the limestone mines became famous for the locals the last time. The pits are shaped in terraces and around 50 m deep to the bottom. The limestone mines shape a stunning landscape. Visitors coming to that place just want to have a look into the pits. Some are taking pictures others just want to have a walk through the rocks.