Since the United States will eventually adopt the metric system, geologists should consider abandoning the nondecimal Udden-Wentworth-Krumbein (UWK) grade scale of particle sizes. Most of the advantages claimed for the UWK system also apply to other geometric grade scales that have an associated log-transform scale. The claim that the UWK major class boundaries are “natural” is not supported by the evidence and is irrelevant. A new grade scale is proposed with major grade boundaries at 0.01, 0.1, 1, 10, and so forth. An associated log-transform scale (the tau scale) is defined so that tau = 12 log10d/d0, where d is grain diameter in millimeters and d0 is 1 mm. The proposed scale has easily remembered grade limits and easily calculated log-transform scale, repeating numbers, major classes of equal interval, and good potential for international adoption and application in other fields.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not have access to this content, please speak to your institutional administrator if you feel you should have access.