Rollability, A Functional Shape Property of Sand Grains

摘要: ABSTRACT The development of a new method to measure behavioral shape property sand grains is presented. This "rollability" related the angle slope on which grain will roll down in air. It measured inside slightly inclined revolving cylinder mantle. emerge from lower end and time it takes them reach this for their rollability. correlates well with influence other processes such as settling water. rollability phi sieve fractions. measurements are transferred relative values. For certain area, mean all values calculated per fraction individual expressed percentile deviations value. In way, strong source material characteristics largely excluded observed differences between samples can be attributed exclusively sorting phenomena. facilitates comparison sediments same depositional circumstances but different s urce. Per sample, graphs plotted show distribution over size called Shape Distribution Character (S.D.C.). appears characteristic mode origin. selection phenomena best understood connection Kuenen's deposit-repository concept. When population split by transport mechanism into two (or more) populations, these populations have complementary regards size, density. Such twin relationship comes out very clearly S.D.C.'s deposit its repository. Examples shown genetic relationships character shallow off-shore zone beach, beach adjoining dunes, eolian cover sands areas been blown out.