Gulf Coast Beaches Research Articles

IMPACT AND PERSISTENCE OF IXTOC I OIL ON THE SOUTH TEXAS COAST

ABSTRACT The blowout of Ixtoc I on June 3, 1979, released at least 476,000 tons of oil into the Gulf of Mexico until the well was capped on March 24, 1980. The predicted northward drift of the oil caused the U.S. government to sponsor a pre-spill coastline mapping project (called the Environmental Sensitivity Index), which was used in developing the response strategy of the U.S. Coast Guard Strike Team and accurately predicted the reaction and persistence of Ixtoc I oil along Gulf Coast beaches when major impacts occurred during August and September 1979. In total, approximately 3,900 tons of Ixtoc I oil washed onto exposed beaches of fine-grained sand and mixed sand and shell in south Texas. Little oil passed into the productive back-barrier lagoons. A tropical storm on September 13, 1979, removed more than 90 percent of the beached oil. By spring 1980, oil remained only as scattered tar mats (8 percent oil, 180 tons total) at the toe of the beach. The quantity of tar balls on the beach could not be differentiated from chronic accumulations.

A Survey of Northwest Florida for Potential Stable Fly Breeding

A survey was made in 15 counties of Northwest Florida and 10 bordering counties in Georgia and Alabama for potential breeding sites of stable flies, Stomoxys calcitrans (L.). Most of the sites found that were capable of breeding tremendous numbers of flies were located at dairies and feedlots, but some were at beef ranches, horse farms, and swine and poultry installations. All of these potential breeding sites were located within 70 miles of the Gulf coast beach resorts, which are within the flight range of the stable fly.

Discriminant Analysis Versus Factor Analysis of Grain-Size Data from Different Environments and Sedimentary Structures: ABSTRACT

Grain-size data analyzed by multivariate computer techniques allows (1) discrimination of environment of deposition and (2) recognition of sedimentary structures. Multiple discriminant analysis where used in conjunction with variables derived from ¼-phi-sieve grain-size analysis was found to be the most useful multivariate technique. Grain-size samples from 3 environments (Arkansas River, Great Sand Dunes National Monument, Colorado, and Gulf Coast beaches) were used as environments in discriminant analysis. With the intention of classifying 49 samples from Bijou Creek, Colorado, they were listed in the discriminant analysis program as unknowns. Thirty-six of 39 unknowns were correctly classified by the program as river sediments. Q/mode factor analysis correctly classified 32 of the Bijou Creek samples with known river samples. Variations in grain-size distributions within a given environment were studied in an Arkansas River sand wave. Foreset beds, climbing ripples, and horizontal laminations were designated as sedimentary structures. By use of multiple discriminant analysis 20 of 21 samples from a second sand wave were classified correctly. Using Q-mode factor analysis all but 3 samples were classified correctly. By analyzing separately each of the 2 or 3 populations appearing as straight lines on cumulative plots on normal probability paper, greater discrimination between environments was obtained than by using standard grain-size parameters calculated by assuming each sample represented a single population. End_of_Article - Last_Page 873------------

Dynamic characteristics of west Florida Gulf Coast beaches

During 1962 fifteen beach stations were established along the Florida coast and monitored at monthly intervals. Observations of beach profiles, sediments, wave conditions, water characteristics and wind speed and direction were recorded. Techniques closely followed those of a nearly contemporaneous study on California beaches ( Ingle, 1966). This made possible a comparison of beach conditions in a low- and medium-energy environment (Florida) with a high-energy environment (California). Average wave conditions in Florida range from low ripples in the low-energy eastern segment near Keaton Beach, to over 30 cm wave height along the broad arc from Cape San Blas to the Alabama-Mississippi peri-delta region. Maximum wave heights reach 100 cm and more along the Pensacola shore and approach the average condition for high-energy beaches. Longshore current velocities, however, are surprisingly constant and range from 30 to 150 cm/sec in the general area. The much larger waves of the California coast produce essentially the same range of current velocities. This is a function of the increase in dimensions of a surf zone as larger waves necessarily break farther offshore, thus the larger amount of water moved in translation is balanced by the increased area. Statistical studies of the sediment textural parameters confirm the observations of Schiffman (1965) regarding the greater variation in texture occurring in the swash zone than in other parts of the beach system. Some evidence suggests that sediment composition differences east and west of Cape San Blas reflect different sources. Magnitudes of profile changes are approximately a direct function of wave height up to average heights of 30 cm and more. Thereafter, increasing wave height apparently does not markedly increase the rate of sand level variation. Volumes of sand transported in longshore drift, however, are directly related to wave height, but show considerable variation from month to month and day to day. Net sand transport is to the west and apparently is actively prograding the large spits of the area from Mobile Bay to Pensacola. Wave energy decreases west of Mississippi Sound and transport diminishes.

Source of beach and river sands on Gulf Coast of Texas

The value of correlations based on heavy minerals is tested on the sands now being deposited on the beaches of the Texas Gulf Coast. Each of the principal rivers carries a distinct suite of heavy minerals. That igneous and metamorphic rocks are a source of a portion of the Rio Grande material is indicated by an assemblage of heavy minerals, exclusive of the opaque black minerals, containing 60 per cent basaltic hornblende and pyroxene, 10 per cent green hornblende, and only 30 per cent of the more stable minerals such as garnet, rutile, staurolite, tourmaline, and zircon. The Nueces, San Antonio, Brazos, Trinity, and Neches rivers derive their load from sedimentary rocks giving a high content of more stable minerals in the heavy-mineral residue with only minor amounts of hornblende and pyroxene. The Colorado River derives its load from igneous, metamorphie, and sedimentary rocks. Its suite of heavy minerals, exclusive of the opaque black minerals, is more than 60 per cent green hornblende with the remainder the more stable minerals. The heavy-mineral residues of the Gulf Coast beach sands commonly contain augite, basaltic hornblende, enstatite, epidote, garnet, green hornblende, hypersthene, kyanite, leucoxene, monazite, rutile, zircon, and from 25 to 50 per cent of opaque black minerals. From the Rio Grande northeastward along Padre Island beach the characteristic Rio Grande suite of heavy minerals, rich in basaltic hornblende and pyroxene, gives way rather rapidly to the Colorado suite rich in green hornblende. The influence of the Nueces, San Antonio, and Brazos rivers is shown by an increased ratio of the more stable minerals. Along the southern two-thirds of Padre Island beach the modal grain diameter is ⅛ mm., and the mode constitutes 90 per cent of the total. A less pronounced, but nevertheless high, degree of sorting persists northeastward along the beaches with ⅛ mm. the modal grain diameter as far as Galveston Island, where the mode shifts to the 1/16 mm. grain diameter size, but the ⅛ mm. grain diameter size is almost as abundant. The distribution of material along the Texas Gulf Coast beaches is effected by a southward longshore current carrying sediment brought to the Gulf of Mexico. The offshore bars on the Texas Gulf Coast may have been formed in this manner.