Wentworth Grade Scale

sedimentology

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 15, 2026

Quick Summary

In sedimentology, a grain size scale divides a continuous range of particle sizes into discrete groups for standardization and statistical analysis. The Udden-Wentworth scale, adapted from J.A. Udden's work, is widely adopted. This scale categorizes particles from finest to coarsest as clay, silt, sand, granules, gravel, pebbles, cobbles, and boulders. The specific size limits for each category can vary between different scales. Grain size is a crucial textural parameter in clastic sedimentary rocks, offering insights into the conditions of sediment transportation, sorting, and deposition, as well as events at the depositional site before lithification.12

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

2 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

sedimentary rock
Grain size
This millimetre, or Udden-Wentworth, scale is a geometric grain-size scale since there is a constant ratio between class limits. Such a scheme is well suited for the description of sediments because it gives equal significance to size ratios, whether they relate to gravel, sand, silt, or clay. The…
Read More
This millimetre, or Udden-Wentworth, scale is a geometric grain-size scale since there is a constant ratio between class limits. Such a scheme is well suited for the description of sediments because it gives equal significance to size ratios, whether they relate to gravel, sand, silt, or clay. The…
Read More

grain size scale
Wentworth, who expanded the definitions of the various grades to conform with actual usage by researchers; most sedimentologists have adopted the Udden scale with the Wentworth modifications.
Read More
Wentworth, who expanded the definitions of the various grades to conform with actual usage by researchers; most sedimentologists have adopted the Udden scale with the Wentworth modifications.
Read More