The Asahi mountain-chain lies on the west side of the Ôu mountain range, the main watershed of the northeastern Japan, and runs parallel to the latter, from north to south. At the southern end of this mountain-chain there is the highest peak of Mt. Daiasahi-dake (1870 m. above the sea) and at the northern end the second higher peak, Mt. Ito-dake (1771 m. above the sea). These mountains are non-volcanic, uplifted blocks and are formed by granitic rocks.
The limnoligical survey of inland waters in the area north of Mt. Ito-dake was carried out by Dr. Masuzo UENO and his collaborators late in July, 1959. With the materials collected in the following waters during this survey, the author studied on the water quality and the diatom flora.
I. Lake Ôtori-ike (the surface area 0.5 km
2, the max. depth 65 m). Water samples from 0, 10, 20, 30, 40, 50, 63 m, respectively.
II. Three inflowing streams on the southern shore of Lake Otori-ike, namely, Higashizawa, Naka-no-zawa, and Nishi-no-zawa.
III. Bog-lake Misumi-ike. Littoral and pelagic samples.
IV. Two small marshes near the summit of Mt. Ito-dake.
The chemical analyses of the water (Table 1) shows that Lake Otori-ike seems to belong to the oligotrophic type, the bog-lake Misumi-ike and the marshes near the summit of Mt. Ito-dake belong to the dystrophic type.
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