Geology of the Southern Plain of Saitama Prefectu

Abstract

The southern plain of Saitama Prefecture is divided by Arakawa and Nakagawa lowlands into three eminences, Iruma, Kitaadachi and Noda, from west to east. Beside these two lowlands, Kawaguchi lowland extends south of Kitaadachi eminence.
These eminences are consisted of diluvium in descending order as follows:
Loam-mainly consists of volcanic ash, 4-5m in thickness
Light colored bed-mainly consists of tuffaceous clay and sand, 10m in thickness
First graval bed-mainly consists of gravel, often changing into sand, 5m in thickness
Upper dark colored-bed mainly consists of clay, often int ercalating thin bedded sand, 20m in thickness
Second gravel bed-mainly consists of gravel, often changing into sand, 10r in thicknes
Lower dark colored bed-mainly consists of clay and sand, about 10-20m in thickness
The lowlands are composed of allvuium in descending order as follows:
Upper clay bed-mainly consists of silt and clay, often intercalating peat, 1-2m in thickness
Upper sand bed-mainly consists of fine sand and clayey sand, 2-3m in thickness
Lower clay bed-mainly consists of sand, rarely changing into gravel, about lm in thickness
Of these strata, soft beds are Loam, Upper dark colored bed of diluvium, and alluvium of lowlands; hard beds are First, Second and Third gravel beds and Lower dark colored bed.