20 OYSTEK BOTTOMS IN MATAGORDA BAY. 



PRINCIPAL OYSTER BEDS IN MATAGORDA BAY. 

 HALF MOON REEF. 



This, the westernmost limit of the survey, is an economically im- 

 portant reef, setting in a generally southwesterly direction from 

 Palacios Point to and beyond Half Moon light. It has a total length 

 of about 5,200 yards and an average width of about 500 yards, em- 

 bracing an area of approximately 494 acres. Between its inner end 

 and Palacios Point there is an area of soft mud, with a width of from 

 300 to 500 yards and a depth increasing from about 1J feet close to 

 shore to upward of 3J feet at low water on and for a short distance 

 beyond the edge of the oyster bed. This deeper water constitutes 

 Palacios Point channel, much used by boats plying to and fro be- 

 tween the upper bay and the town of Palacios. Stretching prac- 

 tically the entire length of the reef, with here and there an interrup- 

 tion, there is a backbone of shells and oysters lying in a depth of 

 less than 1 foot at the mean low water of winter. Surrounding the 

 light there is a depth of about 4 feet, shoaling rapidly on each side. 

 The shoal crest is nearer the southeast side of the reef, and, as in the 

 other long reefs hereafter described, the slope is relatively sharp in 

 that direction, although, excepting the extreme end, there is not so 

 abrupt a rise at the margin as on Dog Island, Shell Island, and Mad 

 Island reefs. 



Excepting at the two ends, where the edges of the bed lie in about 

 3J feet of water, the limit of oyster growth is generally in a depth 

 close to 1 fathom. The reef is growing comparatively rapidly at 

 its outer end, and it now extends from 400 to 500 yards farther 

 toward the southeast than it did when the hydrography of the Coast 

 Survey was executed. That it is a very old reef is shown by the 

 depth from which it rises and by the results of probings through an 

 almost impenetrable mass of shells and compacted fragments at least 

 3 or 4 feet in thickness. As in the cases of the other beds of the 

 region, it began by the fixation of a few oysters to some firm for- 

 eign body lying in mud of a consistency similar to that now sur- 

 rounding it, and upon the shells so grown successive generations set 

 until the whole area became covered and the level was gradually 

 raised higher and higher above the normal bottom. It is still build- 

 ing up, and, as stated, comparison with the previous survey shows that 

 its horizontal dimensions, and particularly its length, are increasing 

 with comparative rapidity. 



According to local witnesses its productiveness has fluctuated 

 greatly, more or less long periods of barrenness having been succeeded 

 by periods of rejuvenescence and fecundity. Local authorities state 

 that there were no oysters on it in 1895 and for several years thereaf- 

 ter, but about 1900 there was a heavy set of spat which grew to market- 



