Sedimentary structures. Their character and physical basis. Volume 2 / Осадочные структуры. Их характеристики и физические основы. Том 2

As the General Preface accompanying Volume I contains an introduction to the work as a whole, it is only necessary for me here to outline the scope of the second volume.
Volume I1 is about sedimentary structures found in relatively complex physical settings, where groupings or hierarchies of features are often of most interest, and more emphasis is placed than in the first volume on cohesive as opposed to cohesionless beds. Secondary currents can exist for a number of reasons in boundary-layer flows, giving rise to flow-parallel sedimentary structures on both kinds of bed.A type of secondary flow arises where river or tidal streams occupy curved channels, with the result that definite vertical and horizontal sequences of sedimentary structures are formed. Flow separation is a phenomenon associated with several kinds of sandy bedform and has a significant though not yet completely understood influence on sedimentation to their lee. Closely related physically is the upward-acting two-phase jet, deposition from which gives rise to sand volcanoes. Separated and secondary flows combined in complex and unpredictable ways are called into being by objects placed on the boundary of a flow. The result is local patterns of scour and deposition expressed as current crescents or drifts. Flute marks in mud beds, and Kurren on limestone and other soluble or partly soluble rock surfaces, record a process of mass transfer in which flow separation in certain instances plays a decisive role. <...>