university of haripur, geology

1. SPHERICITY AND ROUNDNESS
BY Masab Ali
Presentation on

2. ROUNDNESS
During the transportation process, grains may be
reduced in size due to abrasion. Random abrasion
results in the eventual rounding off of the sharp
corners and edges of grains. Thus, the degree
of rounding of grains gives us clues to the amount
of time a sediment has been in the transportation
cycle.Roundness is normally
visually estimated but may also be calculated
from the cross-sectional shape of a clast.

3. SPHERICITY
rounding is not the same a sphericity. Sphericity is
controlled by the original shape of the grain.
In describing individual clasts, the
dimensions can be considered in terms of
closeness to
a sphere . Discoid or needle-like clasts have a low
sphericity. Sphericity is an inherited feature,
that is, it depends on the shapes of the fragments
which formed during weathering. A slab-shaped
clast will become more rounded during transport
and become disc-shaped, but will generally retain
its
form with one axis much shorter than the other two