Central Java ash makes Central Java highly fertile agriculture land. Paddy fields are extensive, except in the southeastern Gunung Kidul region partly due to the high concentration of limestone and its location in a rain shadow from the prevailing weather. The largest rivers are the Serayu in the west, which empties into the Indian Ocean, and the Solo which flows into East Java. On the eve of the World War II in 1942, Central Java was subdivided into 7 residencies (Dutch "residentie" or plural "residenties", Javanese "karésiḍènan" or "karésidhènan") which corresponded more or less with the main regions of this area. These
Oceanic trench to dispose of sediment. An evolution in trench morphology can be expected, as oceans close and continents converge. While the ocean is wide, the trench may be far from continental sources of sediment and so may be deep. As continents approach each other, the trench can fill with continental sediments and become shallower. A simple way to approximate when the transition from subduction to collision has occurred is when the plate boundary previously marked by a trench is filled enough to rise above sea level. Accretionary prisms grow in two ways: by frontal accretion, whereby sediments are scraped off the