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Major Tropical Cyclone (TC) events cause extensive damage in coastal regions of the western North Atlantic Basin. The short instrumental record leaves significant gaps in understanding long-term trends in TC recurrence and intensity, creating uncertainty about future storm trends. Analysis of an ∼520-year core record from Harvey Lake, located >80 km from the Atlantic coast in southwestern New Brunswick, Canada was carried out using: (a) end-member mixing analysis (EMMA) of lake sediment grain size data to identify storm-linked sedimentological processes; and (2) ITRAX X-ray fluorescence (XRF) derived element/ratios (Fe, Ti, Ca/Sr, Zr/Rb, K/Rb, and Br + Cl/Al) associated with precipitation, weathering, catchment runoff, and air masses. Three derived end members were correlated to heavy rainfall events (EM01), spring freshet (EM02), and TCs (EM03). CONISS analysis of the EMMA and XRF core data resulted in recognition of four unique climatic zones distinguished by distinct distributions of TC and rainfall/weathering/runoff/and air masses. Numerous, major (EM01) rainfall events and (EM03) TC events characterized the basal core record during the early Little Ice Age (LIAa; Zone 1) phase, terminating at ∼1645. A near cessation of heavy rainfall and TC events differentiated the subsequent colder LIAb (∼1645–1825; Zone 2) and subsequent Little Ice Age Transition (∼1825–1895; Zone 3). A resurgence of major rainfall and TC events occurred during recovery from the LIA starting in ∼1895 (Zone 4). EMMA provides a robust tool for recognition of TC and major rainfall events, and greatly expands the potential for paleo-storm activity research well inland from coastal regions.

Pac Chen Lake is located on the Yucatan Peninsula, Mexico and is ~ 42 km from the coast and ~ 22 km NE of Coba. It has an area of ~ 36,735 m2 and maximum depth of 25 m. Four sediment cores along a depth transect provide a 4-ka record of the evolution of the eastern deep basin (core PC1 at 25 m depth) and the shallow margin (cores PC2–4 at 0.25–5 m depth). PC1 shows the effect of water-level rise and flooding of the shallow margin (2.8–1.8 ka) through a lithological (organic to carbonate) and geochemical (μXRF; decreased Ti, Fe, K and Ca) change along with a reduction in sediment accumulation (~ 0.2927 to 0.0343 cm year−1). This change in sedimentation matches basal ages of PC2 and PC4 at 2.5 and 1.8 ka respectively, indicating water-level rise and flooding of the shallowly sloped margin which is within estimates of Holocene sea-level rise thus indicating connection with the aquifer. Corroborating evidence for connection with the aquifer comes from water-level monitoring (30 min intervals; 6 months December 12, 2018 to June 6, 2019) which shows a semi-diurnal tidal fluctuation (1–1.5 cm). Droughts have been thoroughly discussed as a proponent of the decline of the Classic Maya, with lakes being inferred to be isolated from the aquifer and experiencing water level drawdown. However, during the Classic Maya droughts lake drawdown in Pac Chen would be minimal, and there is no evidence of a water level drop in our lake margin stratigraphy (PC2–4). Water mass characteristics measured in March 2016 (temperature, conductivity) indicate some hydrological isolation from the aquifer. This isolation would have allowed for recording of environmental changes, but also likely changed through time as flooding of the lake progressed. The shallow margin core PC4, however, recorded several rapid drops in K and Fe from ~ 1100 to 975, and 925–875 yr BP, which we interpret as periods of reduced inputs of terrigenous weathering during times of reduced rainfall and runoff. These periods are consistent with other regional paleoclimate records (lake and speleothem) of the Classic Maya droughts (1200–850 yr BP).

Core-scanning X-ray Fluorescence (XRF-CS) is a well-established technique for rapid (30 replicate analyses for up to 180 samples in a single XRF-CS run. These replicate measurements allow for rigorous testing of precision and accuracy of XRF-CS data. To determine the ideal method of data transformation to improve XRF-CS calibration to quantitative geochemical concentration, 100 lake sediment-surface samples collected from Harvey Lake, New Brunswick, Canada, were analyzed using Itrax-XRF-CS, and then with ICP-MS analysis after multi-acid digestion. Normalization using the CIR and correction for water content showed strong correlation coefficients (Kendall's τ) for elements with atomic number > 18 and high concentrations in the sediment. Results for lighter elements and those with lower concentrations did not perform well using these calibration methods. The MLC provided the most accurate reproduction of observed ICP-MS trends and strong correlations (R) between predicted and actual geochemical concentrations. Based on these results, CIR-normalized or wet-corrected calibrations are ideal for studies where absolute geochemical values are of lesser importance, and the MLC method is appropriate for studies with large numbers of sediment samples (n > 100), or those where absolute concentrations of elements are of greater importance.

A combination of Itrax micro-X-ray fluorescence core scanning (μXRF-CS) and freeze coring can facilitate the development of high-resolution (e.g. sub-decadal) paleoclimate records in lacustrine systems where low sedimentation rates and poorly consolidated “colloidal soup” at the sediment/water interface prevents retrieval and Itrax-μXRF-CS analysis of undisturbed cores using conventional gravity corers. The iBox-FC containment vessel described and tested here delays thawing of highly perishable freeze cores for up to two hours, providing adequate time to carry out high-resolution Itrax-μXRF-CS analysis. The iBox-FC is comprised of an open-topped Styrofoam box divided into chambers using high-density polyethylene (HDPE) that are filled with freeze pack gel. When the vessel is frozen, core slabs up to 13 cm long may be positioned into a central chamber and then scanned following normal Itrax-μXRF-CS methodology. To test the reliability of μXRF-CS analysis obtained from frozen sediments, a freeze core recovered from Control Lake, Northwest Territories, Canada, was sub-sectioned and analyzed using μXRF-CS and then subsampled for ICP-MS following near-total acid digestion. Comparison of μXRF-CS and ICP-MS results showed strong correlations (R2 > 0.8) for six of nine elements calibrated, and moderate correlations (R2 > 0.3) for the remaining three. Additive log-ratio transformation of data minimized specimen, matrix and edge effects associated with the high porewater contents of the freeze cores and slight melting of the sediment during analysis. These analytical effects had more impact on the lower concentration elements (As, Zn, Ni, Cu) than the higher concentration elements (Ti, K, Mn, Fe, Ca).

This study presents a multi-proxy reconstruction of tropical cyclone (TC) activity for the past 800 years from Robinson Lake, located on the north Atlantic seaboard of Nova Scotia, Canada. Two sediment cores were extracted from Robinson Lake and were dated by 210Pb and 14C methods, and analyzed for organic matter content, sediment grain size, and a range of elements and elemental ratios determined by XRF core scanning. A distinct sand layer in the most recent sediments is attributed to Hurricane Juan, which struck the coast of Nova Scotia on September 29, 2003. Our study shows that peaks in grain size farther down-core are generally correlated with abrupt increases in Br and Br/Ti. XRF-derived Br measurements are an indicator of marine organic carbon (MOC), and the increases in Br likely reflect incursions of marine water and nutrients into the lake as a result of storm surges. The results show that the period from ~1475 to 1670 CE contains at least 3–4 storm beds, and are interpreted as the most active TC period within the last ~800 years for this region. Our results are consistent with recent research from Salt Pond, Massachusetts (Donnelly et al. 2015), which provides evidence for heightened TC activity during the same period as our study at Robinson Lake. Our study represents one of the highest latitude paleotempestological studies from the North Atlantic basin which will help the testing of hypotheses concerning long-term changes in North Atlantic TC activity under future climate change scenarios.

A novel geomatics methodology is presented for locating optimal lake coring sites to potentially capture evidence of paleo-storms. One hundred sediment–water interface samples collected from Harvey Lake, NB, Canada (45° 43′ 45″ N; 67° 00′ 25″ W) were analyzed using: end member mixing analysis (EMMA), which can be used to recognize modal grain size distributions derived from sediment resuspension during major storms; and Itrax X-ray fluorescence core scanning-derived Ti, an indicator of catchment runoff, which is enhanced during major storm events. Simple geospatial models based on lake bathymetric and historical wind speed data (Fredericton INTL A climatological station; 1953–2015) were used to determine lake bottom areas susceptible to wave base sediment resuspension. EMMA End Member (EM) 02 (mode = 40 μm) was widely distributed in areas > 4.4 m water depth, which have been unimpacted by wave base remobilization since 1953. Deposition of EM 02 in deeper water areas was interpreted to be of major storm derivation, the result of fallout of resuspended sediments from the water column. This EM was most concentrated in the central part of the lake at >6 m water depth, as well as at the z-max (~ 11 m), and in Herbert’s Cove (3–6 m). The main source of run-off derived Ti into the lake was through Sucker Brook, with the highest concentrations in Herbert’s Cove and the central part of the lake, including the lake z-max. This assessment indicates that the best undisturbed sedimentary record of paleo-storms is mostly likely in the central part of the lake north of the z-max at water depths of > 6 m, as well as deeper water areas of Herbert’s Cove.

Anguilliform-swimming fishes (eels, lampreys) are undergoing large and global declines due partly to an inability to pass dams via traditional fishways. The installation of “eel ladders” (wetted, studded/bristle substrates that permit these fishes to climb over obstructions) offer a potential solution. We examined the behaviour of migrating sub-adult sea lamprey (Petromyzon marinus) as they approached and attempted to ascend a 45° studded ramp in a mesocosm placed in a river. We also examined motivation to use the ramp in the presence of a conspecific alarm cue that signals predation risk. Entrance (75%) and attraction efficiency (85%) were high, but reduced by the presence of alarm cue. In total, 98% of sea lamprey attracted to the base of the ramp ascended, and alarm cue had no effect. Time to ascend the ramp (post-release) was variable (1–521 min) and on average was 119 min (50% probability = 35 min). Few sea lamprey required multiple attempts to ascend (19.8%) and was more likely during longer transit times, with multiple ramp attachments, and with higher body mass. Propensity to attach to the ramp increased with number of attempts. The high efficacy of this design, compared to poor-mediocre efficiencies of similar designs in previous studies, may be related to water velocity and depth, geometry of substrate studs, substrate presentation (horizontal/vertical, and incline), and length of studded substrate. Studded ramps represent a substantial opportunity for managers attempting to selectively pass anguilliform fishes over dams, aiding conservation efforts. Applications to the management of sea lamprey include removal in their non-native Great Lakes range, and fish passage in their native range.

Cave divers discover La Mina, a pristine Paleoindian-age subterranean ochre mine, deep in the now-submerged caves of Quintana Roo., Investigations in the now-submerged cave systems on the Yucatán Peninsula continue to yield evidence for human presence during the Pleistocene-Holocene transition. Skeletal remains are scattered throughout the caves of Quintana Roo, most representing individuals who died in situ. The reasons why they explored these underground environments have remained unclear. Here, we announce the discovery of the first subterranean ochre mine of Paleoindian age found in the Americas, offering compelling evidence for mining in three cave systems on the eastern Yucatán over a ~2000-year period between ~12 and 10 ka. The cave passages exhibit preserved evidence for ochre extraction pits, speleothem digging tools, shattered and piled flowstone debris, cairn navigational markers, and hearths yielding charcoal from highly resinous wood species. The sophistication and extent of the activities demonstrate a readiness to venture into the dark zones of the caves to prospect and collect what was evidently a highly valued mineral resource.

Karstic cave systems are intricately related to surficial processes and the study of cave sediments is a growing field of research. Sediment deposits in caves are protected from surficial weathering processes, and are therefore often preserved. Hidden River Cave is an active, multi-level cave system in the town of Horse Cave, Kentucky with over 33 km of mapped passages. A history of anthropogenic impacts on the cave system include uses for hydroelectric power generation, a water source, and a show cave until it closed in 1943 due to severe contamination from domestic and industrial waste. Analysis of sediment cores from the cave system show distinct concentrations of metals within the sediment from chrome plating plant effluent. Relative concentrations of metals in the core record were obtained using an Itrax core scanner, and were observed to decrease moving downstream from the chrome plating plant contamination source. The chronology of sedimentation events indicates a strong connection between historical contaminating events in the town of Horse Cave and cave sediment deposition. This approach emphasizes how core analysis allows for depositional patterns in the cave system to be determined and related to historic surficial processes. The methodologies emphasis the potential for the analysis of sediment trapped within cave systems may be used to shed insight into a regions anthropogenic and natural events.

Calcite-raft precipitation was monitored in three Yucatan cenotes (Rainbow, Feno and Monkey Dust) over a 2-year period. Site-specific variables including water temperature, relative humidity, water level and salinity were recorded as well as rainfall (Cozumel). Calcite-raft surface area was monitored through trail cameras that collected photographs every 60 min. Accumulation rates were recorded using sediment traps that were collected in May and December of each year. Calcite-raft surface area was calculated using an image segmentation procedure that identified the boundary of objects (edge detection) that share certain pixel characteristics, removed non-points of interest and measured the sum of the area covered by the raft material. Results show that large rainfall events have a regional effect on the meteoric water mass (i.e. salinity), as well as the precipitation of calcite rafts. The large rainfalls and increased inflows cause dilution of the CaCO3 supersaturated meteoric water mass and cause increased flow hindering calcite-raft precipitation for days to weeks after the rainfall. Raft precipitation gradually returns with deceasing flow after the event, and stagnation allows the recurrence of CaCO3 supersaturation and accumulation of nucleation particles. Small rainfalls did not seem to have the same effect, as slower percolation of rainwater through the epikarst would be more saturated and micro-topographic relief may isolate the water pools from the lower flow. The sediment trap data shows that calcite rafts accumulate relatively constantly throughout the year in all three sites. Sedimentation rates from Feno and Monkey Dust responded to seasonal changes in surface-water disturbance associated with rainfall (wet and dry), although Rainbow didn't show any seasonality likely due to other site-specific factors affecting water disturbance (e.g. bats, wind).

Arcellinida (testate lobose amoebae), a group of benthic protists, were examined from 46 sediment-water interface samples collected from oligotrophic Oromocto Lake, New Brunswick, Canada. To assess (1) assemblage homogeneity at a sub-meter spatial scale and (2) the necessity for collecting samples from multiple stations during intra-lake surveys; multiple samples were collected from three stations (quadrats 1, 2, and 3) across the north basin of Oromocto Lake, with quadrat 1 (n = 16) being the furthest to the west, quadrat 2 (n = 15) situated closer to the center of the basin, and quadrat 3 (n = 15) positioned 300 m south of the mouth of Dead Brook, an inlet stream. Results from cluster analysis and non-metric multidimensional scaling (NMDS) analysis identified two major Arcellinida assemblages, A1 and A2, the latter containing two sub-assemblages (A2a and A2b). Redundancy analysis and variance partitioning results indicated that seven statistically significant environmental variables (K, S, Sb, Ti, Zn, Fe, and Mn) explained 41.5% of the total variation in the Arcellinida distribution. Iron, Ti and K, indicators of detrital runoff, had the greatest influence on assemblage variance. The results of this study reveal that closely spaced samples (~ 10 cm) in an open-water setting are comprised of homogenous arcellinidan assemblages, indicating that replicate sampling is not required. The results, however, must be tempered with respect to the various water properties and physical characteristics that comprise individual lakes as collection of several samples may likely be necessary when sampling multiple sites of a lake basin characterized by varying water depths (e.g., littoral zone vs. open water), or lakes impacted by geogenic or anthropogenic stressors (e.g., eutrophication, or industrial contamination).

Lechaion's inner harbour basin was constructed in the 7th-6th c. BCE and served as Corinth's principal port for over a millennium. The harbour decline and abandonment in the 6th c. CE has been attributed to several causes: natural siltation, co-seismic uplift, coastal subsidence, and damage by tsunami impacts. A multi-proxy palaeoenvironmental study was conducted on seven cores from Lechaion's inner harbour to determine changes in the coastal environments and timing and cause of harbour abandonment. Palaeoenvironments were reconstructed using high-resolution micro-XRF core scanning of sedimentary facies, isotopic (δ18O, δ13C), and micropalaeontological analyses (foraminifera, palynomorphs). The harbour lithostratigraphy consists of an uppermost (∼1 m) sequence of laminated mud and marl overlying interbedded pebbly sand and mud containing abundant marine microfossils and Roman pottery refuse. A thin (

The landscape of northeast Ontario, Canada, is dominated by glacial and postglacial landforms including numerous boreal lakes that formed following the retreat of the Laurentide Ice Sheet (LIS) and Glacial Lake Ojibway. This study uses micro-X-Ray Fluorescence elemental analysis to examine changes in sediment cores from two boreal lakes from northeast Ontario with the goal of inferring changes in terrestrial inputs and redox status of these lakes over the middle to late Holocene. These headwater lakes were selected as they have small watersheds that minimizes the complexity of hydrological responses, and as they are relatively proximal (∼130 km distance between lakes) to allow the detection of regional signals related to changes in climate over the Holocene. Strong correlations between Si, K, Ca, and Ti in Hogback Lake and Green Lake cores suggest that these elements represent proxies of terrestrial input. Standardized composite trends of these elements were very similar between the two lakes and were combined to represent a regional signal, with the highest terrestrial inputs between ∼6000 and ∼4000 cal yr BP, that subsequently declined through the Holocene. These results suggest that regional patterns in terrestrial input are linked to changes in hydroclimate and likely increased terrestrial stability over the middle to late Holocene. These composite trends are compared to similar geochemical composite trends from Iceland suggesting climate teleconnections between northeast North America and the North Atlantic. Cool conditions in the North Atlantic result in increased soil erosion in Iceland and correspond to cool and dry conditions in boreal northeast Ontario with corresponding low inputs of terrestrial material, and vice versa, over multidecadal time scales over the middle to late Holocene.

Two cores from calcite rafts deposits located in Cenote Ich Balam and Hoyo Negro were dated and analyzed for 87Sr/86Sr, δ18O, δ13C, Sr/Ca and Cl/Ca. The geochemical records show changing aquifer salinity spanning the last ∼ 8.5 cal kyrs BP and interrelationships with Holocene climate trends (wet and dry periods). During the wet mid-Holocene, the salinity of the meteoric Water Mass (WM; at 7.8–8.3 cal kyrs BP) was relatively high at 1.5–2.7 ppt and then became less saline (1.0–1.5 ppt) during the last ∼ 7000 yrs as climate became progressively drier. High salinity of the meteoric WM during the wet mid-Holocene is attributed to increased turbulent mixing between the meteoric and underlying marine WM. Increased precipitation, in terms of amount, frequency, and intensity (e.g. hurricanes) causes higher flow of meteoric water towards the coast and mixing at the halocline, a phenomenon recorded with recent instrumental monitoring of the aquifer. Conversely, during dry periods reduced precipitation and flow in the meteoric WM would result in lower salinity. Karst properties and Holocene sea-level rise also seem to have an effect on the aquifer. When the regionally extensive network of shallow cave passages (∼ 10–12 m water depth) are flooded at ∼ 8000 cal yrs BP, there is a rapid shift in salinity. This study demonstrates that calcite raft deposits can be used as paleo-environmental recorders documenting the effects of sea level and climate change on aquifer condition.

We report on measurements of the salinity and temperature in the Yax Chen cave system on the Yuacatan peninsula. This paper is submitted together with Kovacs et al. (2017). Kovacs et al. focuses on the salinity levels of the meteoric lens, while this paper uses the observed results to elucidate the hydrodynamics. The cave passages have water depths on the order of 10 m, with flow on the order of ten centimeters a second, and as such is a hydrodynamic, as opposed to a porous, system. The measurements reveal that episodes of significant mixing between the fresh meteoric lens and the underlying salty water are driven by meteorological events (e.g., Hurricane Rina in 2011, and the twin Hurricanes Ingrid and Manuel in 2013). We find evidence that after the hurricanes in 2013, the water column remains unstable for several months. Through wavelet analysis, we find that the marine Water Mass (WM) exhibits much less low period activity compared to the meteoric WM. We hypothesize that the open cenotes are locations of high mixing intensity, with turbulent fronts propagating away from the sites of direct mixing into the cave network. We perform laboratory experiments and numerical simulations to explore this phenomenon, and find that mixing preferentially occurs on the flanks of regions of strong, stable density stratification (i.e., on the periphery of pycnoclines), and leads to entrainment of fluid into the turbulent region. Using high resolution direct numerical simulation, we explore the detailed manner in which turbulent entrainment can drive flow toward the mixing region, and lead to mixing of passive tracers. Finally, we discuss the implications of these results for the mixing of passive tracers, such as suspended chemicals.

There is a lack of information on aquifer dynamics in anchialine systems, especially in the Yucatan Peninsula of Mexico. Most of our knowledge is based on “spot” measurements of the aquifer with no long-term temporal monitoring. In this study spanning four years (2012–2016), sensors (water depth and conductivity (salinity)) were deployed and positioned (−9 and −10 m) in the meteoric Water Mass (WM) close to the transition with the marine WM (halocline) in 2 monitoring sites within the Yax Chen cave system to investigate precipitation effects on the salinity of the coastal aquifer. The results show variation in salinity ( 95 mm) such as Hurricane Ingrid (2013) and Tropical Storm Hanna (2014) shows meteoric water mass salinity rapidly increasing (approx. 6.39 to >8.6 ppt), but these perturbations have a shorter duration (weeks and days). Wavelet analysis of the salinity record indicates seasonal mixing effects in agreement with the wet and dry periods, but also seasonal effects of tidal mixing (meteoric and marine water masses) occurring on shorter time scales (diurnal and semi-diurnal). These results demonstrate that the salinity of the freshwater lens is influenced by precipitation and turbulent mixing with the marine WM. The salinity response is scaled with precipitation; larger more intense rainfall events (>95 mm) create a larger response in terms of the magnitude and duration of the salinity perturbation (>1 ppt). The balance of precipitation and its intensity controls the temporal and spatial patterning of meteoric WM salinity.

We use sediments from a flooded sinkhole (Cenote Jennifer) in northern Cuba to provide new, well-dated, high-resolution evidence for the 8.2 kyr event. From ~7600 to 8700 cal yr B.P. the sinkhole contained shallow, low-salinity water, which supported a marsh dominated by cattail and grass. Peaks in Cl and Br—occurring at 8150, 8200, and 8250 cal yr B.P.—are attributable to increased evaporation due to regional drying associated with the 8.2 kyr event. The three peaks in these elements also closely correspond to the greyscale record from the Cariaco Basin, indicative of increased upwelling in the southern Caribbean Sea at this time, supporting the notion of a multistage 8.2 kyr event. Our work provides new data that help to clarify the initiation, behavior, and impacts of the 8.2 kyr event in the northern tropics.

Extraordinary marine inundation scattered clasts southward on the island of Anegada, 120 km south of the Puerto Rico Trench, sometime between 1200 and 1480 calibrated years (cal yr) CE. Many of these clasts were likely derived from a fringing reef and from the sandy flat that separates the reef from the island’s north shore. The scattered clasts include no fewer than 200 coral boulders, mapped herein for the first time and mainly found hundreds of meters inland. Many of these are complete colonies of the brain coral Diploria strigosa . Other coral species represented include Orbicella (formerly Montastraea ) annu­laris , Porites astreoides , and Acropora palmata . Associated bioclastic carbonate sand locally contains articulated cobble-size valves of the lucine Codakia orbicularis and entire conch shells of Strombus gigas , mollusks that still inhabit the sandy shallows between the island’s north shore and a fringing reef beyond. Imbricated limestone slabs are clustered near some of the coral boulders. In addition, fields of scattered limestone boulders and cobbles near sea level extend mainly southward from limestone sources as much as 1 km inland. Radiocarbon ages have been obtained from 27 coral clasts, 8 lucine valves, and 3 conch shells. All these additional ages predate 1500 cal yr CE, all but 2 are in the range 1000–1500 cal yr CE, and 16 of 22 brain coral ages cluster in the range 1200–1480 cal yr CE. The event marked by these coral and mollusk clasts likely occurred in the last centuries before Columbus (before 1492 CE). The pre-Columbian deposits surpass Anegada’s previously reported evidence for extreme waves in post-Columbian time. The coarsest of the modern storm deposits consist of coral rubble that lines the north shore and sandy fans on the south shore; neither of these storm deposits extends more than 50 m inland. More extensive overwash, perhaps by the 1755 Lisbon tsunami, is marked primarily by a sheet of sand and shells found mainly below sea level beneath the floors of modern salt ponds. This sheet extends more than 1 km southward from the north shore and dates to the interval 1650–1800 cal yr CE. Unlike the pre-Columbian deposits, it lacks coarse clasts from the reef or reef flat; its shell assemblage is instead dominated by cerithid gastropods that were merely stirred up from a marine pond in the island’s interior. In their inland extent and clustered pre-Columbian ages, the coral clasts and associated deposits suggest extreme waves unrivaled in recent millennia at Anegada. Bioclastic sand coats limestone 4 m above sea level in areas 0.7 and 1.3 km from the north shore. A coral boulder of nearly 1 m 3 is 3 km from the north shore by way of an unvegetated path near sea level. As currently understood, the extreme flooding evidenced by these and other clasts represents either an extraordinary storm or a tsunami of nearby origin. The storm would need to have produced tsunami-like bores similar to those of 2013 Typhoon Haiyan in the Philippines. Normal faults and a thrust fault provide nearby tsunami sources along the eastern Puerto Rico Trench.

Gregory, B.R.B.; Reinhardt, E.G., and Gifford, J.A., 2017. The influence of morphology on sinkhole sedimentation at Little Salt Spring, Florida. Sedimentary processes are important for understanding sinkhole records of climate and sea-level change. This study examines Little Salt Spring (LSS), an hourglass-shaped sinkhole near the SW coast of Florida, to determine the influence of sinkhole morphology on sedimentation. An 8.27-m core recovered from LSS was subsampled at 2-cm intervals for particle-size, loss-on-ignition, and stable-isotope analyses (δ13C, δ15N, and C:N ratios). Nineteen radiocarbon dates provide chronology and sediment accumulation rates over the past approximately 13,500 cal. YBP. Particle size shows alternating periods of coarse and fine sediment from 6600 to 13,500 cal. YBP and coarser sediment from 0 to 6600 cal. YBP. Organic matter (OM) and carbonate content (CC) are initially low (