A clastic sedimentary particle showing very little or no evidence of abrasion, with
all of its edges and corners sharp, such as blocks with numerous (15-30) secondary
corners and a roundness value between 0.17 and 0.25 (midpoint at 0.21).
source
Powers, M. C., 1953 A new roundness scale for sedimentary particles. Journal of Sedimentary
Petrology, v. 23, p. 117-119
A clastic sedimentary particle whose original edges and corners have been smoothed
off to rather broad curves and whose original faces are almost completely removed
by abrasion (although some comparatively flat surfaces may be present), such as a
pebble with a roundness value between 0.49 and 0.70 (midpoint at 0.59) and few (0-5)
and greatly subdued secondary corners. The original shape is still readily apparent.
source
Powers, M. C., 1953 A new roundness scale for sedimentary particles. Journal of Sedimentary
Petrology, v. 23, p. 117-119
A clastic sedimentary particle showing definite effects of slight abrasion, retaining
its original general form, and having faces that are virtually untouched and edges
and corners that are rounded off to some extent, such as a glacial boulder with numerous
(10-20) secondary corners and a roundness value between 0.25 and 0.35 (midpoint at
0.300).
source
Powers, M. C., 1953 A new roundness scale for sedimentary particles. Journal of Sedimentary
Petrology, v. 23, p. 117-119
A clastic sedimentary particle showing considerable but incomplete abrasion and an
original general form that is still discernible, and having many of its edges and
corners noticeably rounded off to smooth curves, such as a cobble with a reduced number
(5-10) of secondary corners, a considerably reduced area of the original faces, and
a roundness value between 0.35 and 0.49 (midpoint at 0.41).
source
Powers, M. C., 1953 A new roundness scale for sedimentary particles. Journal of Sedimentary
Petrology, v. 23, p. 117-119