The writer's purpose is to offer a classification and method of measurement of conglomerates im field geology., 1., Conglomerates shuld be defined as aqueous, coarse clastics with a cover degree ((surface ratio) of gravels more than 5%., 2., The constituent elements of conglomerate are: a) kinds of lithology of gravels and their ratio, b) size of gravels and their ratio, c) roundness of gravels and their ratio, d) cover degree (surface ratio), e) sorting, f) kinds of lithology of matrix and grade of its induration., 3., According to combination of above-mentioned elements, we can classify conglomerates as is shown in Table 2., 4., The object of making the satistics of gravels in a given river bed at present are to test the method of measurement of gravels taken, and to obtain clues to ascertain the conditions of topography, lithology and of sedimentation, which formed land, at the time of deposition., 5., writer measured recent gravels of the Arakawa river bed for a preliminary examination and derived the conclusion which can be applied also to conglomerates., a) Kinds of lithology of gravels indicate the strata and igneous rocks at the time of deposition of conglomerates., b) The mixture ratio of gravels indicate the width of the place of distribution of the lithology to which the gravels belong and the grade of erosion., c) Roundness of gravels indicate how far the gravels have been move., And it is possible to guess from the difference of roundness of gravels belong to the same lithology, the relative distance of the place of distribution., Yet, angular gravels do not necessarily indicate how far they have been moved., Therefore, in order to guess by the roundness of gravels how far they have been moved, gravels of higher grade of roundness should be paid attention to., d) The degree of erosion of gravel depend on the hardness of rock., Therefore the existence of boulders of soft rocks, indicate that the place of distribution of the strata and igneous rocks to which the gravel belongs is near., Yet though the existence of boulders of high grade and a hard rock shows enough conditions to carry the gravels, it can not be concluded immediately that the place of distribution is near by., And seldom do soft gravels travel a long distance., Therefore the meaning of the existence of soft gravels is great, and they should not be missed even when there are only a few., Soft gravels also help to guess how far they have been carried., Therefore to guess the distance of transportation by the mixture ratio of gravels, the existence of soft gravels should be paid attention to., 6., From his experience of the Arakawa river bed, the present writer worked out the methods of measurement of conglomerates, linear method, quadrate method and correlation method.,
