collected at stations less than 1 nautical mile 

 apart with a chartered shrimp boat, Gus III . 



Although our major effort has been devoted 

 to the collection of data, three papers have 

 been published on preliminary work conn pleted 

 during three of the cruises. Also completed 

 was a new map (fig. 23) of the Gulf of Mexico 

 in a confornnal Lambert conic projection with 

 the depth contours in meters. Navigationalaids 

 are now generally lacking in the western Gulf, 

 but after Loran stations are installed in this 

 area, we plan to update the chart frequently 

 from soundings obtained by the R/V Geronimo . 



After completion of the cruise for ground 

 support for the Gen-iini XII nnanned space flight, 

 the Naval Oceanographic Office assigned two 

 contracts to this program: one to evaluate 

 space photography and its application to fish- 

 eries and one to conduct a cruise in support of 

 the first manned Apollo space flight. 



John R. Grady, Acting Program Leader 



RECONNAISSANCE SURVEY 



Benthic and hydrographic samples were col- 

 lected during two cruises of the R/V Geronimo 

 to the west Florida shelf. Samples were taken 

 as far north as Cape San Bias along transects 

 which were about 93 km. (50 nautical miles) 

 apart, except around the Dry Tortugas, where 

 the effort was more concentrated. A total of 

 416 benthic samples were taken, and 33 hydro- 

 graphic stations were occupied across the 

 Continental Shelf and slope. The stations were 

 distributed over the continental terrace to tie 

 together areas that have been studied in detail 

 with unworked areas. 



Van Veen and orange peel grabs were used 

 to obtain sediment samples on the Continental 

 Shelf; a short coring tube was used over the 

 slope and abyssal plain. These samples have 

 been processed, and the textural and statistical 

 properties computed. Results are being plotted 

 on newly prepared charts of the area. 



On the southern, west Florida shelf, the 

 linnestone bottom is covered by a thin veneer 

 of unconsolidated sediments which are chiefly 

 of calcareous organic origin. Distribution and 

 composition vary from zones of quartz-shell 

 sand, roughly paralleling the coast, to an 

 almost connpletely foraminiferal sand on the 

 outer edge of the shelf and down the slope. 

 Off the northern shelf, south of the Florida 

 panhandle, the inshore zone of the detrital 

 component is considerably more extensive 

 than on the southern shelf. The organic origin 

 of the sediments, particularly on the southern 

 slope and shelf, appears to be the dominant 

 factor controlling the size distribution of par- 

 ticles. 



Fossil assemblages were dredged from the 

 slope during the cruises to Florida waters. 



We believe that these ancient forms mark old 

 strand lines formed during the Pleistocene 

 when sea levels were lower than at present. 



A cooperative cruise with Texas A&M Uni- 

 versity was nnade in Decennber along the 

 183-m. (100-fathom) isobath off the Mexican 

 coast south of the Rio Grande. The objectives 

 of this cruise were: (1) to deternnine if any 

 residual effects of Hurricane Inez were evi- 

 dent in the waters over which it passed; (Z) to 

 obtain bottom sediments along three transects 

 for study and comparison with nnaterial pre- 

 viously collected elsewhere in the Gulf; and 

 (3) to locate and verify a large-scale feature, 

 about 28 by 56 km. (15 by 30 nautical miles) in 

 dimension, shown on navigation charts as 

 an eastward projection of the Continental Shelf 

 near Tampico, Mexico. 



All objectives of the December cruise were 

 fulfilled. Analysis of temperature, salinity, 

 dissolved oxygen, and productivity data taken 

 at depths across the track of Hurricane Inez 

 showed so residual effects of the storm. Short 

 cores of sediment were obtained at 14 stations 

 on a 138.7-km. (75-nautical nnile) traverse off 

 Tecoluta and at 11 stations on a 101.7-km, 

 (55-nautical mile) traverse off Punta Penon. 

 Echo soundings along the transects revealed 

 rugged ridge and trough topography with the 

 axis about parallel to the coast. In addition, 

 although a number of echo sounding tracks 

 were connpleted off Tampico, no projection of 

 the Continental Shelf was observed. We con- 

 sider it probably nonexistent, or mislocated 

 on navigation charts. 



During the year, 2,473 water samples were 

 collected at depth on hydrographic surveys 

 made to coastal waters south of Louisiana, 

 Mississippi, and Alabama in November for 

 "ground-truth" support of the Gemini XII 

 manned space flight and throughout the Gulf of 

 Mexico, including the Bay of Campeche and 

 the Yucatan Straits. The dissolved oxygen con- 

 tent of these samples was determined aboard 

 ship and frozen samples of the water were 

 brought to our laboratory for analyses of 

 the nutrient salts. Determinations of the 

 phosphate-phosphorus and slicate-silicon 

 content of these samples are nearing com- 

 pletion. 



The final cruise of the year in June was 

 made to survey a large canyon crossing the 

 outer slope about 333 km. (180 nautical miles) 

 south of Galveston. Short cores were taken 

 along the axis of the canyon. Exploration of 

 the canyon complex was prompted by a need 

 for a hydrographically acceptable area for 

 waste disposal near Galveston. Echo sounding 

 tracks taken in this area will be used to update 

 the conic projection of the Gulf of Mexico 

 prepared at this Laboratory. 



John R. Grady, Project Leader 



31 



