What does roundness tell us about sediment grains?

Answer 1

it tells us about the transportation of sediments before deposition. i.e if a sediment has travelled a longer distance, it'll be rounder. therefore the longer the transportation takes, the well-rounded it becomes

Answer 2

Roundness of sediment grains can provide information about the distance the grains have traveled from their source. Well-rounded grains have likely traveled a long distance and experienced multiple episodes of erosion and transport. On the other hand, angular grains are typically indicative of shorter transport distances and limited weathering.