ABSTRACT

The sediment size characteristics were determined for 53 samples of sediment, from Matagorda Bay, Texas. The Foraminifera were studied in 21 of these samples. The dominant sediment in the Bay was a silty clay, with sand and shell generally distributed around the marginal area.

The Foraminifera consisted almost completely of calcareous forms, although a very few arenacecus forms occurred in some localities. This did not agree with results of investigations in other bays along the Texas Coast where the arenaceous population was much larger. The reason may be attributed to hydrographic factors which do not permit a population of arenaceous fauna comparable to those in other bays.

The distribution of the Foraminifera showed a general tendency for increasing population density in the eastern portion of the Bay, with minimal population occurring in Pass Cavallo. The greatest average density of Foraminifera was in the Mid-Bay sedimentary environment. The average density decreased in the Bay Marginal and Reef areas, and the Bay Inlets. Large variations in total populations were present within the same environment.

A poor correlation was indicated by the graphical relationship of the total population to the median diameter of the sediments. However, in comparing the population of Elphidium gunteri, one of the dominant forms, with the median diameter, there was an indication that the higher population occurred in the silt range.

The reason for the foraminiferal distribution may be connected with a combination of hydrographic and sedimentary factors. The available data did not allow evaluation of these factors.