Which statement best defines well sorted sediment?

• A. Grains have varied sizes
• B. Grains have similar size
• C. Grains are all quartz
• D. Grains have different mineralogy

Answer: (B)

Sorting is about how uniform the grain sizes are in a sediment. Well-sorted sediment has grains that are similar in size, produced when transport energy stays relatively constant and deposits mostly grains within a narrow size range. Larger particles get winnowed away and finer particles settle, but the overall size range remains small. This contrasts with poorly sorted sediment, which contains a mix of very coarse to very fine grains due to fluctuating energy during deposition. Mineralogy isn’t what sorting measures, so a deposit dominated by quartz can be well or poorly sorted depending on the grain-size distribution. So the idea that grains have similar size best defines well-sorted sediment.