The Geology and Formation of Kushiro
The geology of Kushiro has been influenced by glaciation, changing sea levels, and volcanic activity. Over time, distinctive landscapes developed, including wetlands and a variety of different marine environments.
Kushiro Wetlands
The Kushiro Wetlands began forming some 6,000 years ago when a period of sustained global cooling caused sea levels to fall, exposing previously submerged coastal plains. The wetlands support thousands of species of plants and animals, including the Japanese crane (Grus japonensis, called tancho in Japanese). The Kushiro Wetlands are the largest in Japan, covering 28,788 hectares.
Volcanic lakes
During the last ice age, several calderas formed to the north of the Kushiro Wetlands. Calderas are craters that take shape when the central part of a volcano collapses in on itself. The craters that formed here filled with water to become Lake Akan, Lake Mashu, and Lake Kussharo, the latter of which is the largest caldera lake in Japan. Lake Kussharo feeds the Kushiro River, which traverses the wetlands and empties into Kushiro Bay.
Kushiro Bay
Kushiro Bay is a geologically diverse environment that supports a wealth of marine life. The bay is divided into two sides by an underwater canyon. The west side has a gentle, sandy shoreline, and the east side has steep, rocky cliffs. The marine life of the Kushiro Submarine Canyon and the shoreline environment is distinct: Flatfish flourish in the sandy shoreline area and deep-sea shrimp and crabs populate the slopes of the marine canyon.