For the first time, electron spin resonance optical dating (ESROD) has been conducted on littorally transported and aeolian siliciclastic sediments in Florida. ESROD utilizes light-sensitive radiation-sensitive defects at silicon sites that have been replaced by aluminum and titanium atoms to give rise to a time-dependant signal. These defects saturate at higher levels of radiation dose, compared to optically stimulated luminescence, and therefore extend the optical dating range back into the millions of years. Our results show that the Trail Ridge Sequence is a multi-depositional unit that began deposition around 2.2 Ma and continued until 6 ka. The Osceola Cape, of the Effingham Sequence, was deposited around 1.5 Ma, and the Chatham Sequence was a multi-depositional terrace with at least three events preserved.

Taphonomic processes are informative about the magnitude and timing of paleoecological changes but remain poorly understood with respect to freshwater invertebrates in spring-fed rivers and streams. We compared taphonomic alteration among freshwater gastropods in live, dead (surficial shell accumulations), and fossil (late Pleistocene–early Holocene in situ sediments) assemblages from two Florida spring-fed systems, the Wakulla and Silver/Ocklawaha Rivers. We assessed taphonomy of two gastropod species: the native Elimia floridensis (n = 2504) and introduced Melanoides tuberculata (n = 168). We quantified seven taphonomic attributes (aperture condition, color, fragmentation, abrasion, juvenile spire condition, dissolution, and exterior luster) and combined those attributes into a total taphonomic score (TT). Fossil E. floridensis specimens exhibited the greatest degradation (highest TT scores), whereas live specimens of both species were least degraded. Specimens of E. floridensis from death assemblages were less altered than fossil specimens of the same species. Within death assemblages, specimens of M. tuberculata were significantly less altered than specimens of E. floridensis, but highly degraded specimens dominated in both species. Radiocarbon dates on fossils clustered between 9792 and 7087 cal BP, whereas death assemblage ages ranged from 10,692 to 1173 cal BP. Possible explanations for the observed taphonomic patterns include: (1) rapid taphonomic shell alteration, (2) prolonged near-surface exposure to moderate alteration rates, and/or (3) introduction of reworked fossil shells into surficial assemblages. Combined radiocarbon dates and taphonomic analyses suggest that all these processes may have played a role in death assemblage formation. In these fluvial settings, shell accumulations develop as a complex mixture of specimens derived from multiple sources and characterized by multimillennial time-averaging. These findings suggest that, when available, fossil assemblages may be more appropriate than death assemblages for assessing preindustrial faunal associations and recent anthropogenic changes in freshwater ecosystems.

The Ryan/Harley site (Florida Master Site File Number: 8Je-1004) is a Middle Paleoindian habitation site containing Suwannee points. Based on stratigraphic correlation and diagnostic artifact seriation, Suwannee-age sites have been relatively dated from ~10,900 14 C yr B.P. to ~10,500 14 C yr B.P. Clovis-like traits on the Suwannee points and other stone tools from the Ryan/Harley site suggest it dates to the earlier end of the Suwannee timeframe. The currently inundated site is partially buried beneath a sediment column located in a swamp forest and partially exposed in a side channel section of the Wacissa River, Jefferson County, Florida. Research done prior to this analysis determined that the artifact assemblage appeared to be unsorted and was contained in a midden-like unit. Our purpose here is to assess the issue of site integrity further. Unconsolidated sediment samples collected from the artifact-bearing horizon and from horizons immediately above and below the artifact horizon were analyzed using granulometric techniques. Arithmetic probability plots of the grain-size distributions show that the sediments were transported and deposited by fluvial processes. Thus, the Suwannee points and associated artifacts, and faunal remains appear to have accumulated during a time of subaerial exposure perhaps after a regional water-table decline, and have remained largely or essentially intact, with little or no postdepositional reworking. The artifacts and faunal remains recovered from the artifact-bearing horizon at Ryan/Harley are distributed randomly, showing no sign of sorting. In the fossil suite, two articulated white-tailed deer (Odocoileus virginianus) vertebra were recovered in situ. The unsorted nature of artifacts and articulated faunal remains that are contained within the fluvially deposited sediments suggests the Suwannee point level of the Ryan/Harley site has remained undisturbed since original deposition.

Seven coreholes (about 200 ft deep) were drilled in western Collier County into the surficial aquifer system. Coreholes were logged with natural gamma-ray, induction, resistivity, neutron, caliper, temperature, spontaneous potential, televiewer, and heat-pulse flowmeter logs, where feasible. Cores have been described and sampled for thin sections, XRD analysis, and Sr dating of shells, and for mollusk, foraminifer, ostracode, pollen, and dinoflagellate cyst content. After coreholes were completed with fully screened plastic casing, flow profiles under ambient and steady injection conditions were used to identify flow paths within the aquifer system and infer locations of confining units. Flowmeter data indicate that permeability is the highest in the rocks under the caprock, from a depth range of about 30 to 50 ft; that zone is characterized by estimated permeabilities of > 1000 ft/day. Preliminary lithologic analysis of cores indicates that the surficial aquifer system comprises a mixed carbonate-siliciclastic deposit of an unnamed carbonate and siliciclastic unit at the base which is overlain by the Tamiami Formation and younger units. The most permeable portion of the aquifer system occurs from 30 to 50 ft depth, in highly leached, moldic and sandy limestones. Locally, tightly cemented beds and poorly sorted sands confine these porous units. The surficial aquifer system is compartmentalized into aquifers of increasingly more saline (with depth) ground water by thin (3m) zones of poorly sorted, unconsolidated siliciclastics. The current model for the surficial aquifer system comprises the lower Tamiami aquifer that is separated by a semi-confining unit from the overlying water-table aquifer. The base of the surficial system is generally considered to be the low permeability clays of the Hawthorn Group, however, the Hawthorn Group was not recognized in any of the cores drilled for this study. In general, the results of this study support the current model however, some areas appear more complexly compartmentalized than the simple two aquifer system. At the turn of the century, the Kissimmee River-Lake Okeechobee-Everglades wetland ecosystem in south Florida covered about 2.9 million acres (Davis, 1943), and seasonal flooding of the lake sent water flowing over its southern rim as overland sheet flow on a sluggish journey to Florida Bay and the Gulf of Mexico. In the early part of this century, the state of Florida began the construction of canals, and later levees, to control flooding of Lake Okeechobee and to drain the wetlands for residential and agricultural use. In the 1930's and 1940's, cross-peninsula highways, like the Tamiami Trail and Alligator Alley, not only brought development and cypress logging into southwest Florida, but also created obstructions to that sheet flow to the southwest coast. In the 1960's, drainage of the Big Cypress swamp of southwest Florida accelerated with the construction of the Golden Ga...

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