64 ^> IvANEnABA 



and Iwasliiro. Small lenticular masses of limestone in the upper part 

 of the Series contain Lepidocydina, AmpMstegino., Gypsina, Operculina, 

 Bliogypsina, LitliotUamnium, etc. which are of Miocene type, and the 

 lower part of the Series is considered to belong to the Palae gene or 

 possibly also to the Mesozoic. 



(B) Neogene : 



T]:ie greater part of the Neogene Series consists of shallow sea 

 deposits mixed with some fresh-water ones. The marine Neogene is 

 most widely spread in North Japan and contains '^ Thyasira-Phacoides 

 Fauna " of Yabe. 



The older Neogene is characterized by the presence of the plants 

 of the " Pre-Pliocene Flora " of Nathorst, although sometimes also 

 by the occurrence of Miogypsina and NephroJepidina limestones. 



The rocks are sandstones, shales, cherts and conglomerates with 

 a considerable amoiuit of pyroclastics ; and the strata are strongly 

 tilted or folded. They have a wider distribution than the younger 

 Neogene, and constitute high hills and mountainous regions. 



The younger Neogene abounds in molluscan fossils which mostly 

 belong to the species living in the neighbouring seas. The rocks are 

 unconsolidated clays, sands, gravels, soft shales, sandstones, conglom- 

 erates and tuffs. The strata are in most cases only slightly disturbed 

 or nearly horizontal, and shows in many cases a distinct clino- 

 unconformity with the underlying older Neogene. In some cases, 

 however, especially in the oil-fields of ISTorth Jajjan, the boundary 

 between these formations is not quite clear, so that they are usually 

 regarded as conformable. 



The uppermost part of the Neogene Series indicates a shallow sea 

 or fresh-water facies, usually consisting of coarse materials such as 

 loose sands and gravels with some clay layers and occasional tuffs. 

 It forms either low terraces or flanks of hills, frequently covered by 

 the Pleistocene gravel beds. This Sei'ies is very oiten underlaid un- 

 conformably by another Tertiary formation and is known as the 

 '' Uppermost Tertiary " or " Diluvio-Tertiary ". 



The mutual relations of the Neogene formations found in the 

 Kwanto district mav be s-iven as follows : — 



