The development of cave passage in Donomulyo, Malang-Indonesia

The cave passages formed in Donomulyo sub–district are formed in epigenic and hypogenic conditions in coastal areas. The dominant factors form the morphological condition of the cave passage that is the existence of structural factors, underground water flow, and tectonism that affect the condition of the passage. Structural factors form the existence of linement that affect the cave passage. Underground water flow forms a passage due to the change of vadose, epipreatic, and phreatic conditions. The existence of tectonism leads to the removal of limestone into several levels of cave passage development, in addition, there is the collapse of blocks, plates, talus, and sheets. The development of the cave passage level is also related to surface physiographic, which is connected to 5 levels with marine terrace, including 244–325 masl (level 1), 182–244 masl (level 2), 111–181 masl (level 3), 30–110 masl (level 4), and 0–29 masl (level 5). The development of fifth level shows that the level limit is located in the Sengik Cave, the fourth level is located in the Jebrot Cave, and the second level is located in the Banyu Cave, these three caves are the output of the underground rivers.