Particles of different angularity

In this experiment, two different types of particles were used. One was rounder with a smoother surface, while the other was rougher and more angular. I expected the latter to have higher intergranular friction and therefore greater angle of repose.

	More angular gravel
Angle of repose — 45°

	Rounder gravel
Angle of repose — 41°

Conclusion: As expected, angular gravels interlock better than round gravels and have a greater angle of repose. They produced an angle of 45° against 41° of the rounder gravel.