Eighteen spar with wells over 1000 m deep have recently been exploited in the Kanto Plain．They have potentially high temperatures ranging from 30 to 45℃．The spa waters can be divided into two groups based on their water quality．The first is characterized by relatively higher contents of dissolved matter，especially organic matter，bromine and iodine．The second group has lower contents of dissolved matter and relatively lower temperature．Radiocarbon ages often spa water
range from 25 k to 35 k years before present，suggesting relatively older water age than those measured in the sedimentary basins．δ^13C and δ^13N values were detemined for estimation of the odgin of the waters（derivation from higher plants or marine planktons）and to provide fundamental data for evaluation of water quality change due to utilization of the spar in the future．Th/Sc ratios of slurries from drilling are useful for discrimination of strata widely distributed in Kanto plain．The Miocene Miura Group is charactedzed by ratios which change from 0.8 in its lower part to less than 0.1 in its upper part，suggesting change to an immature provenance．The Plio-Pleistocene Kazusa Group has Th/Sc＝0.4，and is therefore characterized by a less primitive provenance．