A survey conducted in February of 1998 located an anomaly originally believed to be the remains of L'Aimable. L'Aimable was one of four ships utilized by Rene-Robert Cavelier, Sieur de La Salle, for his voyage to colonize the Gulf Coast in 1684. The anomaly, a wrecked vessel with a heavy iron signature, was located outside the entrance to the historic pass into Matagorda Bay, Texas. Artifacts were extracted from the wreck site to aid in the identification of the vessel, which was subsequently determined to be more recent in origin. A preliminary examination of the artifacts indicates that the shipwreck dates to the first half of the 19th century. The survey recovered over two hundred artifacts. The assemblage of artifacts includes over 80 lead shot, over 40 examples of brass firearm furniture, over 15 firearm fragments, several pieces of copper sheathing, and iron bar stock. Almost two-thirds of the material is associated with small arms. The majority of the identifiable firearms are military arms of three patterns: the British Short Land Pattern, the British India Pattern, and the 1757 Spanish musket. Historical research has determined that these arms were circulating in Texas, New Orleans, and Mexico, as early as 1815. The British Pattern arms were both purchased for the Mexican army in the 1820s, and used by the British Infantry in the Battle of New Orleans in 1815. The 1757 Spanish musket was used chiefly by Spanish expeditionary forces in North America in the late 18th century. Evidence garnered from the artifacts suggest that the firearms were shipboard cargo onboard a small, wood-hulled sailing vessel that wrecked between the years 1815 and 1845. Archival and historical research isolated nine wreck candidates for this period. Historical research and artifact analysis suggest the Hannah Elizabeth as the primary candidate for this wreck site. The Hannah Elizabeth was a small merchant schooner from New Orleans laden with a munitions cargo for Texas troops stationed at Goliad. The vessel wrecked at the entrance of the historic Pass Cavallo while evading capture from a Mexican brig-of-war in November of 1835.

Because the volume of flow through an inlet is proportional to the tidal range and the area of the tidal basin, Texas tidal inlets have some of the largest tidal basins relative to their entrance area of any inlet. Matagorda Bay at Pass Cavallo has an area of about 200 square miles, but only a mean diurnal tidal range of about 1.1 feet. From tide gage records the most important events modifying tidal currents in Pass Cavallo are the numerous wind tides each year that occur most frequently during the cooler months, November through May. Wind tides are most noticeable in Matagorda Bay because the astronomical tidal range is small, the fetch long (10-20 miles) and the depth only about 12 feet. Hurricanes and river floods that would raise water levels in Matagorda Bay by even 0.5 foot occur too infrequently to affect equilibrium conditions in the inlet. Pass Cavallo has passed through three time periods since 1856: 1856-1930, 1930-1965, and post 1965. Each time period was characterized by a different, and subsequently smaller tidal discharge, cross-sectional area and tidal channel length. The tidal discharge decreased between 1929 and 1935 when the Colorado River delta cut off part of east Matagorda Bay to reduce the tidal area of Matagorda Bay, and in 1965, the Matagorda Ship Channel was dredged across Matagorda Peninsula to reduce the volume of water passing through Pass Cavallo. Other features that changed with decreasing discharge, but remained stable during each time period, were the channel pattern, and location and shape of the Gulf bar and Pelican Island. During all three periods Pass Cavallo maintained stable cross-sectional shape, and tidal flow by-passing characteristics, except during the post 1965 when neither tidal flow by-passing nor bar by-passing were dominant. Since 1856 Pass Cavallo has remained geographically stable relative to its width. The axial trough has migrated southwestward about 1000 feet during the past 100 years--or about 1/9th the distance between Matagorda Peninsula and Matagorda Island. Shorelines adjacent to the inlet also have tended to move southwestward, but at a faster rate than the axial trough. Along the western side of the pass, shoreline erosion is related to jetties interrupting sediment transport southward from the western shoreline of Matagorda Bay, and to storms eroding the constructional beach extending northward from Matagorda Island. The modern flood delta at Pass Cavallo consists of a large, sandy platform, that is lobate into Espiritu Santo Bay with salt marsh, storm-tidal flats and tidal channels. The flood delta is located to the side of the channel pattern of Pass Cavallo, and appears to be active only during the high tides of hurricanes, tropical storms and "northers". There are three informal physiographic provinces on the flood delta, each one reflecting a different sediment supply and energy regime inherent in each bay and in the Gulf. 1) The Gulf of Mexico Province has the largest and best-developed intertidal beaches, surge channels, storm-tidal flats and mounds of all three provinces. Sand is the dominant sediment. 2) Matagorda Bay Province includes large marsh islands and tidal channels with fewer large vegetated mounds. Shell is very abundant in mounds, and a storm-tidal flats contain more mud and encroaching salt marsh than in the Gulf province. 3) Espiritu Santo Bay Province is composed mostly of sandy mud or muddy sand sediment, with the exception of erosional shell beaches that face a north or south fetch of 1 to 2 miles. This is the richest area biologically, consisting mostly of salt marsh and grassflats. / text