size sediments, or seismic records show the sand deposits vary consider- 

 ably in thickness and areal extent); "high priority borrow areas," part 

 of C and D (areas located on the shoal south of Galveston Inlet and in 

 the vicinity of the ebb tidal shoal near San Luis Pass) . The most per- 

 tinent information on the five borrow areas is contained in Table 2. Of 

 the 34 cores obtained (see App. A), 84 samples from 20 cores (3, 5, 11, 

 12, 14 to 19, 21 to 28, 33, and 34) had enough sand for textural analysis 

 (see App. B) . Appropriate textural data are summarized for each borrow 

 area in Table 2. 



a. High Island to Crystal Beach . Of the cores taken in this region, 

 only cores 3 and 5 contain sand in quantity. Core 5, taken about 4 kil- 

 ometers (2.5 miles) off Gilcrest, contains only about 30 centimeters 



(1 foot) of fine sand at the bottom of the core; the thick overburden of 

 soft mud and stiff clay eliminates this as a possible borrow site. Core 

 3 in area A (Fig. 16) was taken in a filled stream channel about 5.5 kil- 

 ometers (3.3 miles) offshore. This channel extends close to shore (Fig. 

 16) but is not visible on the seismic profile closest to shore. The sand 

 in core 3 is very fine and present as thin lenses interbedded with silts 

 and clays which make the material of marginal quality for beach fill. 

 However, it is the best prospect in the Gilcrest-High Island offshore 

 region. The volume estimate of 6.8 million cubic meters (8.9 million 

 cubic yards) for this deposit (Table 2) includes the fine-grained constit- 

 uents as well as the sand. The net volume of sand is probably 50 to 70 

 percent of the estimate. The remaining cores in this region contain stiff 

 gray-green clay or cohesive mud. Seismic records show numerous other 

 buried channels but they are either too small to be significant sand 

 repositories or they are filled with cohesive modern muds as shown in 

 cores 8 and 9 (App. A). The seismic records also show a thinly buried 

 pipeline crossing area A in a shore-parallel orientation just inshore of 

 the 9.1 -meter (30 feet) depth contour. This is a 50.8-centimeter (20 

 inches) gasline which would preclude dredging in the immediate vicinity. 



b. Galveston Inlet . Borrow area B is adjacent to the north jetty of 

 Galveston Inlet and contains cores 11 and 12 (Fig. 17). Core 11 was taken 

 on the flank of a buried channel about 4 kilometers off Bolivar Beach; 

 core 12, taken in 7 meters (23 feet) of water, penetrated the fill of the 

 ancestral Trinity River. Both cores contain sand but the entire area 

 appears to be overlain by about 1 meter (3 feet) of very soft mud (Table 

 2) . To remove the sand in area B the mud overburden would have to be 

 removed and disposed of in an environmentally acceptable manner. It is 

 possible that the overburden becomes thinner toward shore, but removal of 

 material in water shallower than 5.5 meters could aggrevate erosion on the 

 adjacent shore and is not recommended without evaluating the impact. 



Borrow area C to the south of Galveston Inlet is triangular in plan 

 view and comprises the lower shoreface and shoal area off Galveston Beach 

 (Fig. 17). It actually consists of two areas. The area of highest poten- 

 tial includes cores 15, 17, and 18 which contain relatively clean, fine- 

 grained sand interbedded with thin mud and muddy sand layers. Seismic 

 records show that the horizontal stratification in the cores extends 



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