10 OYSTEB BOTTOMS OF MISSISSIPPI EAST OF BILOXI. 



The following designations used to indicate the different degrees 

 of hardness, as shown by the instrument, are arbitrary, although 

 based on the terms used by the oyster growers: 



Hard Penetration less than 4 inches. 



Stiff Penetration between 4 and 8 inches. 



Soft Penetration between 8 and 13 inches. 



Very soft Penetration between 13 and 18 inches. 



Ooze Penetration over 18 inches. 



These various types of bottom are shown on the chart by means of 

 circles, the relative area of black included within them indicating 

 the relative degree of hardness, as follows: Hard, a black circle; 

 stiff, a black semicircle; soft, a black quadrant; very soft, two cross- 

 ing diameters; ooze, one diameter. 



The bottoms classed as hard and stiff, those in which the plunger 

 will not penetrate more than 8 inches, are suitable for planting 

 without preparation, provided they are not composed of shifting 

 sand. As sand iavariably gives a reading of less than 4 inches, and 

 is therefore rated as ''hard,'^ it follows that all ''stiff" bottom shown 

 on the chart by a black semicircle can be accepted as safe for planting. 

 Part of the hard bottom is composed of mud and part of sand. The 

 former may be accepted without hesitation, but the latter should be 

 examined with respect to its liabiUty to shift. Soft bottom should be 

 planted with care, and toward its upper or less consistent limits may 

 require some preliminary hardeniug with shells or sand. Very soft 

 bottom and ooze should not be considered, as oysters planted there 

 will siak, and if not killed, as is probable, will be ill shaped and 

 inferior iu every respect. The ratings on which the classification is 

 based have been checked by observation on bottoms actually used 

 for oyster culture in Chesapeake Bay. 



The instrument employed has been thoroughly tested and is reli- 

 able for the purposes of oyster surveys, but there may be errors ia 

 cases where hard bottom is overlaid by several iuches of soft mud 

 and ooze. Such bottoms are always readily detected by probing 

 with a pole. 



During the course of the survey 10,472 soundings were made and 

 1,826 angles for the position of the boat were taken on lines aggre- 

 gating a length of 211 miles, over which the chain was dragged 

 continuously. In addition to the soundings and the use of the chain 

 on the beds, oysters were tonged, examined, and counted, and other 

 biological observations were made at 129 places. The barren bot- 

 toms were tested with the instrument previously described at 343 

 places, at each of which from 6 to 10 observations were made. The 

 data of the survey therefore includes upward of 10,000 soundings, 

 211 miles of continuous chain readings, and 472 special examinations 

 of the bottom and its contents. The whole area covered was about 

 75,000 acres, of which 1,708 acres were oyster-bearing bottom. 



