A geochemical investigation (major cations and anions, stable isotopes of oxygen and hydrogen, pH, and salinity) was conducted to identify the sources of groundwater recharge to the surficial aquifer system in Everglades National Park. The weighted mean values of δ 18 O and δD of rainfall were −2.83‰ and −10.59‰, respectively. A mean deuterium excess value of 12 suggests that evaporation of Everglades surface water contributes between 7% and 12% to the local precipitation. Most shallow groundwater in the surficial aquifer system (<28 m) is recharged throughout the year by Everglades surface water and or canal water exposed to evaporation. Recharge rates between 2 cm/yr and 12 cm/yr were obtained, with the higher rates in areas of little to no standing water. Deep groundwater in the surficial aquifer system (>28 m) is recharged directly from rainfall far upgradient of the northern boundary of Everglades National Park. Groundwater from the underlying Hawthorn Group is geochemically distinct from the surficial aquifer system and recharges the surficial aquifer system from below. There is no geochemical evidence of surface water or shallow groundwater flow between the two major waterways (Shark Slough and Taylor Slough) in Everglades National Park. In this investigation, a combination of stable isotopes (δ 18 O and δD) and major-ion data was necessary to identify different sources of groundwater recharge to the karst aquifer. The stable isotopes (δ 18 O and δD) were most useful in deciphering between rainfall and surface-water recharge to the shallow aquifer, whereas the major-ion data were used to identify recharge from deeper aquifers and seawater intrusion.

Abstract: This study investigated the extent to which deep-dwelling, infaunal foraminifera bias modern and fossil distributions in the subtropical mangroves of the Everglades (southwest Florida), and which sediment interval should be used as a modern analog for paleoenvironmental studies in this area. Typically, these studies are based on modern analogs from the upper 1 to 2 cm of sediments, as most benthic foraminifera live in the surface 1 cm, but in tropical mangrove environments, deep-dwelling infaunal foraminifera may be more common. The vertical distributions of live assemblages in cores from a mudflat and three mangrove sites were investigated. To examine the preservation potential of dead tests, distributions of wall types and inner test linings were recorded. The living depths of benthic foraminifera showed a landward deepening from 1 to 3 cm in mudflats and low mangroves and from 7 to 10 cm in middle and high mangroves, possibly due to a landward increase in oxygenation of the subsurface sediments. Modern assemblages from the top 2 cm included species common in the deep infauna and contained, on average, 36% of the total standing crop. Additions to total assemblages at greater depths by subsurface production were negligible. Thus, the upper 2 cm of the sediment column would be sufficient as a modern analog for paleoenvironmental studies in the southwestern Everglades. Preservation of dead tests is influenced by a landward increase in the degradation of agglutinated taxa through oxidation/bacterial breakdown of organic cements. Fortuitously, calcareous taxa preserve well in the carbonate-buffered sediments of the Everglades.

ABSTRACT The mid-Cenozoic succession in the northeast limb of the Mount Diablo anticline records the evolution of plate interactions at the leading edge of the North America plate. Subduction of the Kula plate and later Farallon plate beneath the North America plate created a marine forearc basin that existed from late Mesozoic to mid-Cenozoic times. In the early Cenozoic, extension on north-south faults formed a graben depocenter on the west side of the basin. Deposition of the Markley Formation of middle to late? Eocene age took place in the late stages of the marine forearc basin. In the Oligocene, the marine forearc basin changed to a primarily nonmarine basin, and the depocenter of the basin shifted eastward of the Midland fault to a south-central location for the remainder of the Cenozoic. The causes of these changes may have included slowing in the rate of subduction, resulting in slowing subsidence, and they might also have been related to the initiation of transform motion far to the south. Two unconformities in the mid-Cenozoic succession record the changing events on the plate boundary. The first hiatus is between the Markley Formation and the overlying Kirker Formation of Oligocene age. The succession above the unconformity records the widespread appearance of nonmarine rocks and the first abundant appearance of silicic volcanic detritus due to slab rollback, which reversed the northeastward migration of the volcanic arc to a more proximal location. A second regional unconformity separates the Kirker/Valley Springs formations from the overlying Cierbo/Mehrten formations of late Miocene age. This late Miocene unconformity may reflect readjustment of stresses in the North America plate that occurred when subduction was replaced by transform motion at the plate boundary. The Cierbo and Neroly formations above the unconformity contain abundant andesitic detritus due to proto-Cascade volcanism. In the late Cenozoic, the northward-migrating triple junction produced volcanic eruptive centers in the Coast Ranges. Tephra from these local sources produced time markers in the late Cenozoic succession.

The regional Floridan aquifer system has been dewatered and otherwise altered extensively throughout much of Florida and coastal Georgia by groundwater pumpage (mining). An increasing threat to this karst aquifer system is structural mining of aquifer formations, primarily to produce fertilizers, titanium products, construction materials, and pet food supplements. These excavations often include mechanical dewatering to facilitate shallow and deep extraction of the aquifer formations. All include reduced aquifer levels, dewatering of the aquifer system, and altered hydroperiods at and surrounding the excavated pits, due to increased void space and evapotranspirative losses (nonmechanical dewatering). Only mechanical dewatering is considered by regulatory agencies during evaluations of applications for structural mining of the aquifer system. Despite refuting data, open pits resulting from these excavations increasingly are portrayed as subsurface “reservoirs” that create new or enhanced sources of water in areas where natural groundwater supplies have been depleted. Four permits and sites were evaluated for excavated and proposed pits in SE, NW, SW, and east-central Florida's natural areas used for groundwater supply. The combined surface area for pits under those four permits will result in ∼237,000 m 3 /d (∼62.7 million gallons per day [Mgd]) of induced discharge from the regional Floridan aquifer system due to nonmechanical dewatering. This volume is more than twice the reported pumpage from the combined three municipal supply wells at the Miami-Dade West Well Field. The ∼123 ha (∼308 ac) SW Florida mine, most recently excavated in an area designated as critical habitat for the federally listed Florida panther, will result in induced aquifer discharge of ∼1505 m 3 /d (0.4 Mgd) due to nonmechanical dewatering. This loss is equivalent to ∼5% of all water used by domestic supply wells in that county in 1990. That recently initiated excavation in SW Florida revealed environmental damage extending beyond the mine boundaries, to surrounding private property, and is the first documented case of such damage solely from aquifer formation mining and nonmechanical dewatering of the aquifer system. A federal court ruled on 22 March 2006 that the U.S. Army Corps of Engineers and U.S. Fish and Wildlife Service had failed to carry out their duty to protect the federal wetlands and protected species by issuing permits for mining in the SE case-study area.

Abstract The mid-Atlantic region and Chesapeake Bay watershed have been influenced by fluctuations in climate and sea level since the Cretaceous, and human alteration of the landscape began ~12,000 years ago, with greatest impacts since colonial times. Efforts to devise sustainable management strategies that maximize ecosystem services are integrating data from a range of scientific disciplines to understand how ecosystems and habitats respond to different climatic and environmental stressors. Palynology has played an important role in improving understanding of the impact of changing climate, sea level, and land use on local and regional vegetation. Additionally, palynological analyses have provided biostratigraphic control for surficial mapping efforts and documented agricultural activities of both Native American populations and European colonists. This field trip focuses on sites where palynological analyses have supported efforts to understand the impacts of changing climate and land use on the Chesapeake Bay ecosystem.