Particle Shape

Clastic Sediments Particle Size Outline
Particle shape is an important property in detrital sediments. There are many descriptive terms that are applied to particle shape. The initial shape of weathered particles is effected by mineralogy: micas tend to platey, feldspars are often tabular, quartz tends to be equant. Ellipsoidal, cylindrical and spherical particles are generated by abrasion.

With increased transport distances, particles become abraded and rounded. Water is the most effective transport medium for rounding particles. Wind abrasion can also generate near spherical particles. Ice transport can sometimes carry particles over large distance with little or no abrasion.

The mechanical strength of granular medium relies of friction between particles. In general, angular particles with low sphericity tend to mobilize more friction than rounded partlicles. On the other hand, rounded or spherical particles tend to pack together more effectively to create denser sediments.

Clastic Sediments Particle Size Outline
(c) Department of Civil and Geological Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK, Canada, S7N 5A9