In South America the Guiana and Brazil shields on the east side are separated from each other by the Amazonas basin. In the west side of the continent the Andean mountain system provided with the Pampean highland on its east side extends from Venezuela to Chile and the fossiliferous Cambro-Ordovician formation is extensively distirubuted in the east side of the mountain system. The history of research in the Cambro-Ordovician biostratigraphy is here summarized. An Olenellian species, two Albertan faunules and a few Croixian genera are known of the Andean Cambrian fauna. Now various graptolites are known there from Tremadocian to Ludlovian. In 1937 I have published a study on “the Cambro-Ordovician shelly fauna of South America”. Our knowledge was considerably improved by Harrington and Leanza's “Ordovician Trilobites of Argentina” 1957, particularly in the Lower Ordovician part. A few Ashgillian trilobites were discovered at length in the San Juan area by Baldis and Blasco (1975) and thus the six ages of the Ordovician period are all documented. Finally, brief notes are appended on the history of the Andean belt in the Palaeozoic and later pe-riods with reference to other arears.
About one fourth of the total production of electricity in Japan was generated in nuclear power plants in 1985. Now, the disposal of radioactive wastes is a major environmental problem. The Japanese islands locate in the tectonically active zone around the Pacific Ocean. Four major lithospheric plates collide or scratch each other in or near Japan. Major earthquakes often shake the Japanese islands where active faults distribute densely. Eruption of volcanoes and hot springs indicate high geothermal activity. However, many observations indicate that shocks of earthquakes are much milder at the depth of some hundred meters than at the ground surface. Some areas even in Japan have been free from volcanic activities during the last tens of millions years. High density of fractures in rocks due to past tectonic disturbances are more serious problems for the isolation of radioactive wastes, as some of fractures might provide pathways for hazardous contaminated water. Major efforts should be paid to develop precise techniques which allow us three dimensional mapping of underground fractures with no hurt to rock body which provides the natural barrier against the migration of radionuclides. The long-term performance of the waste isolation system should be estimated adequately. The knowledge of recent tectonic activities (Quaternary tectonics) and the study of natural analogues provide a basis for long-term prediction of the stability of the burial site.