4 N. Yamasaki 



along the Sea of Japan. Some large emLaj-raents and cliannel?, such 

 as the hays of Tokyo, Sagami, Suruga, Ise and Tosa, and the channels 

 Kii and Bungo, are of tectonic origin. Even the famous Inland Sea, 

 or Setouchi, which stretches between the Main Island, or Honshu, and 

 two other large islands, Shihoku and Kyushu, is nothing but a 

 longitudinal zone of depression, consisting of a series of small seas or 

 nada. Further, the coast is in many places fringed with small 

 indentations, such as those of rias type in the submerged coast of 

 northeastern Honshu and that of Kii Peninsula. The shore of the 

 Sea of Japan is comparatively smooth and straight. Tlie volcanic 

 peninsula of Oga and the projected horst of ISToto, together with the 

 depressed bays of Toyoma, Tsuruga and Wakasa, break the monotony 

 of this coast line. Similarly, the west and south coasts of the Korean 

 Peninsula are remarkably configurated with numberless bays and inlets, 

 in which are scattered thousands of islands of various sizes, in contrast 

 to the simple shore, bare of islands, of the Sea of Japan to the east. 



iii. Seas. The most important sea near Japan is, of course, the 

 Pacific Ocean. Not only for its vast extension but also for the 

 profundity of its abyss near the archi])elago, does it merit special 

 attention. Most parts of the Japan trench or grahen. which extends 

 quite a long distance along Chishima, the main islands of Hokkaido, 

 north Honshu, and farther south along the eastern side of the volcanic 

 islands of Tdzu, are deeper than 7,000 metres; and the well-known 

 Taskarora Deep, not far off the Kunashiri Islands, is 8,515 metres. 

 Another deep of 8,491 metres off the coast of the Kitakami moun- 

 tainland and one of over 9,000 metres to the south of Boso Peninsula, 

 have recently been sounded. An accurate sounding of the latter has 

 not yet been i-egistered. The deep, narrow trench along the outer side 

 of the Ryukyu Islands, with a maximum depth of 7,481 metres, is 

 also a very remarkable one. Tiie existence of other trenches along 

 Palau, Yap and Guam in the southern sea have already been recorded. 

 Quite recently, however, the discovery has been made by a surveying 

 boat of a deep in the Mariana trench with the record dex)th of 9,814 

 metres, which surpasses by some twenty metres or more that of the 

 world-known Swire Deep in the Philippine trench. 



Between the Japanese islands and the continent, there are three 

 seas, which are barely connected with each other by narrow channels. 

 The most important one is the Sea of Japan. Enclos(;d by the central 

 arc of the islands to tlie south and east, and by the Korean Peninsula 



