gradient tints
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gradient tints
[′grād·ē·ənt ‚tins] (mapping)
A series of color tints used on maps or charts to indicate relative heights or depths. Also known as elevation tints; hypsometric tints.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
hypsometric tinting

Above tints are in shades of brown.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved