Plateau and Lowland

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Minato City is located at the southeast end of the Musashino Plateau. Its elevation gradually decreases from west to east as it reaches the coast via lowland at an elevation of less than 5m. The highest elevation in Minato City is 34m, with the lowest being 0.08m. Minato City’s upland, stretching to the west, has a hard layer of earth starting with the Kazusa Group on the bottom with the Tokyo Gravel Layer on top, and the Kazusa Group, and the Tokyo Formation on top of the other two layers. The Tokyo Formation is a layer of earth with its upper portion consisting of three layers, namely alluvium at the base, followed by the Kanto Loam Formation (including the Musashino and Tachikawa Loam Formations), with a layer of the Shimosueyoshi Loam Formation (including the Shibuya Clay Layer) in the upper portion of the formation. The depositional age of the Shimosueyoshi Loam Formation is old, and has been eroding for a very long time, which is why Minato City is very hilly. At the eastern area of Minato City is the lowland consisting of several layers of earth. At the bottom, like the upland’s makeup, is the Kazusa Group. Following that is the Lower Tokyo Formation, with the Tokyo Gravel Layer and the Upper Tokyo Formation on top. Moving toward the surface, the next three layers consist of the Sand and Mud Layer, the Mud Layer, and the Sand Layer. Both the Minato City upland and lowland areas are covered by the Soil Layer that was deposited after the Edo period.