Stable imbrication and delicate/unstable settings in coastal boulder deposits: Indicators for tsunami dislocation?

Abstract

Medium sized and coarse debris (pebbles and boulders) can exhibit patterns of setting, particularly if they are elongated or tabular. These patterns, such as imbrication, indicate certain transport processes, mostly as to direction and character. Many years of observation and measuring of coarse coastal deposits, are the basis for the conclusions presented here on environmental transport processes, their character, and their energy. Beside imbrication, special emphasis is given to unstable or delicate settings of large boulders that evidently have remained in these positions from hundreds to thousands of years. This deserves an explanation to how they arrived at these positions, and why they have not changed into a more stable position, given an environment of constant energy input along coastlines. The discussion lays emphasis on whether both settings of (mega-) boulders can be indicative of tsunami transport processes. © 2014 Elsevier Ltd and INQUA.