character of the bottom
character of the bottom[′kar·ik·tər əv thə ′bäd·əm]
In marine operations, the type of material of which the bottom is composed; a sounding lead is sometimes armed with tallow or similar substance so that a sample of the bottom is obtained when a sounding is made; the sample is often helpful in determining position. Also known as nature of the bottom.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.