Ryumon Formation

Coherent formation
Pliocene - Pleistocene
Correlation: upper Denoto Formation

Sedimentary facies: Fluvial
Paleo-river system: Yoshinogawa river
Lithofacies: Gravels
Lithofacies (Minor): Mud, Sands

Thickness: ca. 50 - 80 m or thicker
Lower limit: Unconformity (Oyodo Formation, Izumi Group, Sanbagawa Metamorphic Rocks)

Shobudani Group (Yoshino, Nara pref.)
[ Upper ]
~~~~~~~~~~~~~~
Ryumon Formation
~~~~~~~~~~~~~~
Oyodo Formation
--------------
Kosoku Formation
~~~~~~~~~~~~~~
[ Lower ]

------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown

Distribution: Shiga - Chimata, Yoshino city, Yoshino county, Nara pref.

Makimoto et al. (2004) Geology of the Kokawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 89p. (in Japanese with English abstract 4p.)
Hirayama and Kambe (1959) Koyasan, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 41p. (in Japanese with English abstract 7p.)
Hirayama and Kishimoto (1957) Yoshinoyama, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 44p. (in Japanese with English abstract 8p.)