Monotis-bearing formations are distributed in 22 local areas of Japan except Hokkaido (Fig. 1). This distribution reflects the zonal geologic structure of the Japanese Islands and its development. Therefore, Monotis-bearing formations are classified here into the following three provinces in accordance with the generally accepted structural divisions:

1. Southern Kitakami Mountains, Northeast Japan

1) Ofunato, 2) Kesennuma, 3) Tsuya, 4) Utatsu

2. Inner Zone of Southwest Japan (including Okutone area)

2-1 Shallow-sea facies
1) Okutone, 2) Tsuyama, 3) Nariwa, 4) Asa

2-2 "Slump" facies
1) Myogatani, 2) Shuzan, 3) Mukaihata

3. Outer Zone of Southwest Japan (including Kwanto Mountains)

1) Ohme, 2) Itsukaichi, 3) Sakuradani, 4) Sakawa, 5) Itadorigawa, 6) Kubodani, 7) Toncgoyama, 8) Miyamadani, 9) Arase, 10) Misaka, 11) Takagochi

It is important for the paleontological study of Monotis to investigate various characters of the fossil beds. In this chapter, the stratigraphy of these Monotis-bearing sediments is described in some detail.