Peter J. van Hengstum

The tsunami of 13 December A.D. 115 and the destruction of Herod the Great's harbor at Caesarea Maritima, Israel

Underwater geoarchaeological excavations on the shallow shelf (∼10 m depth) at Caesarea, Israel, have documented a tsunami that struck and damaged the ancient harbor at Caesarea. Talmudic sources record a tsunami that struck on 13 December A.D. 115, impacting Caesarea and Yavne. The tsunami was probably triggered by an earthquake that destroyed Antioch, and was generated somewhere on the Cyprian Arc fault system. The tsunami deposit consisted of an ∼0.5-m-thick bed of reverse-graded shells, coarse sand, pebbles, and pottery deposited over a large area outside of the harbor. The lower portion of the deposit was composed of angular shell fragments, and the upper portion of whole convex-up Glycymeris spp. shells. The sequence records tsunami downcutting (∼1 m) into shelf sands, with the return flow sorting and depositing angular shell fragments followed by oriented whole shells. Radiocarbon dating of articulated Glycymeris shells, and optically stimulated luminescence (OSL) dates, constrain the age of the deposit to between the first century B.C. and the second century A.D., and point to the tsunami of A.D. 115 as the most likely candidate for the event, and the probable cause of the harbor destruction.

Climate forcing of unprecedented intense-hurricane activity in the last 2000 years

How climate controls hurricane variability has critical implications for society is not well understood. In part, our understanding is hampered by the short and incomplete observational hurricane record. Here we present a synthesis of intense-hurricane activity from the western North Atlantic over the past two millennia, which is supported by a new, exceptionally well-resolved record from Salt Pond, Massachusetts (USA). At Salt Pond, three coarse grained event beds deposited in the historical interval are consistent with severe hurricanes in 1991 (Bob), 1675, and 1635 C.E., and provide modern analogs for 32 other prehistoric event beds. Two intervals of heightened frequency of event bed deposition between 1400 and 1675 C.E. (10 events) and 150 and 1150 C.E. (23 events), represent the local expression of coherent regional patterns in intense-hurricane–induced event beds. Our synthesis indicates that much of the western North Atlantic appears to have been active between 250 and 1150 C.E., with high levels of activity persisting in the Caribbean and Gulf of Mexico until 1400 C.E. This interval was one with relatively warm sea surface temperatures (SSTs) in the main development region (MDR). A shift in activity to the North American east coast occurred ca. 1400 C.E., with more frequent severe hurricane strikes recorded from The Bahamas to New England between 1400 and 1675 C.E. A warm SST anomaly along the western North Atlantic, rather than within the MDR, likely contributed to the later active interval being restricted to the east coast.

The intertropical convergence zone modulates intense hurricane strikes on the western North Atlantic margin

Most Atlantic hurricanes form in the Main Development Region between 9°N to 20°N along the northern edge of the Intertropical Convergence Zone (ITCZ). Previous research has suggested that meridional shifts in the ITCZ position on geologic timescales can modulate hurricane activity, but continuous and long-term storm records are needed from multiple sites to assess this hypothesis. Here we present a 3000 year record of intense hurricane strikes in the northern Bahamas (Abaco Island) based on overwash deposits in a coastal sinkhole, which indicates that the ITCZ has likely helped modulate intense hurricane strikes on the western North Atlantic margin on millennial to centennial-scales. The new reconstruction closely matches a previous reconstruction from Puerto Rico, and documents a period of elevated intense hurricane activity on the western North Atlantic margin from 2500 to 1000 years ago when paleo precipitation proxies suggest that the ITCZ occupied a more northern position. Considering that anthropogenic warming is predicted to be focused in the northern hemisphere in the coming century, these results provide a prehistoric analog that an attendant northern ITCZ shift in the future may again return the western North Atlantic margin to an active hurricane interval.

A Coastal Yucatan Sinkhole Records Intense Hurricane Events

ABSTRACT Brown, A.L.; Reinhardt, E.G.; van Hengstum, P.J., and Pilarczyk, J.E., 2014. A coastal Yucatan sinkhole records intense hurricane events. The potential of tropical sinkholes as archives for historical hurricane events has yet to be fully explored. This study uses high-resolution (1-cm interval) particle-size analysis to examine two sediment push cores from Laguna Chumkopó, located on the Yucatan Peninsula, Mexico. Core CKC1 (62 cm) was collected from the base of a deep sinkhole located in Laguna Chumkopó at −79.9 m (msl), while the second core, CKC2 (93 cm), was collected from the shallow peripheral margin at −6.4 m (msl). Two coarse fining upward sequences (12 to 35 cm, 46 to 62 cm) in CKC1 had mean particle sizes of approximately 1.5 φ (medium sand) with intervening intervals of lime mud (<4 φ). Measured 137Cs activity in the bulk sediment (n = 15) and radiocarbon dating (n = 3) using bomb-carbon calibration determined that the lower coarse unit was deposited in the 1960s (after September 1957 AD), and the upper unit between January 1985 and August 1991 AD. Hurricane Gilbert struck the Yucatan on 15 September 1988 as a category 5 storm, generating the upper fining upward sequence. Hurricane Beulah (category 2–3) likely generated the lower unit when it struck on 18 September 1967. CKC2 revealed small textural changes, alternating between silt and sand-sized particles and radiocarbon ages dated to ∼6.7 to 7.1 ka. The rapid accumulation of sediment in the shallow lagoon likely occurred with rising sea level flooding the area at approximately 6.8 ka. Based on the sedimentary results, a depositional model is proposed for inland sinkholes, explaining the formation of hurricane deposits through density and debris flows along the shallow margin.

Low‐frequency storminess signal at Bermuda linked to cooling events in the North Atlantic region

North Atlantic climate archives provide evidence for increased storm activity during the Little Ice Age (150 to 600 calibrated years (cal years) B.P.) and centered at 1700 and 3000 cal years B.P., typically in centennial-scale sedimentary records. Meteorological (tropical versus extratropical storms) and climate forcings of this signal remain poorly understood, although variability in the North Atlantic Oscillation (NAO) or Atlantic Meridional Overturning Circulation (AMOC) are frequently hypothesized to be involved. Here we present records of late Holocene storminess and coastal temperature change from a Bermudian submarine cave that is hydrographically circulated with the coastal ocean. Thermal variability in the cave is documented by stable oxygen isotope values of cave benthic foraminifera, which document a close linkage between regional temperature change and NAO phasing during the late Holocene. However, erosion of terrestrial sediment into the submarine cave provides a “storminess signal” that correlates with higher-latitude storminess archives and broader North Atlantic cooling events. Understanding the driver of this storminess signal will require higher-resolution storm records to disentangle the contribution of tropical versus extratropical cyclones and a better understanding of cyclone activity during hemispheric cooling periods. Most importantly, however, the signal in Bermuda appears more closely correlated with proxy-based evidence for subtle AMOC reductions than NAO phasing.

Thecamoebians (Testate Amoebae) Straddling the Permian-Triassic Boundary in the Guryul Ravine Section, India: Evolutionary and Palaeoecological Implications.

Exceptionally well-preserved organic remains of thecamoebians (testate amoebae) were preserved in marine sediments that straddle the greatest extinction event in the Phanerozoic: the Permian-Triassic Boundary. Outcrops from the Late Permian Zewan Formation and the Early Triassic Khunamuh Formation are represented by a complete sedimentary sequence at the Guryul Ravine Section in Kashmir, India, which is an archetypal Permian-Triassic boundary sequence [1]. Previous biostratigraphic analysis provides chronological control for the section, and a perspective of faunal turnover in the brachiopods, ammonoids, bivalves, conodonts, gastropods and foraminifera. Thecamoebians were concentrated from bulk sediments using palynological procedures, which isolated the organic constituents of preserved thecamoebian tests. The recovered individuals demonstrate exceptional similarity to the modern thecamoebian families Centropyxidae, Arcellidae, Hyalospheniidae and Trigonopyxidae, however, the vast majority belong to the Centropyxidae. This study further confirms the morphologic stability of the thecamoebian lineages through the Phanerozoic, and most importantly, their apparent little response to an infamous biological crisis in Earth’s history.

Increased hurricane frequency near Florida during Younger Dryas Atlantic Meridional Overturning Circulation slowdown

15 The risk posed by intensification of North Atlantic hurricane activity remains 16 controversial, in part due to a lack of available storm proxy records that extend beyond 17 the relatively stable climates of the late Holocene. Here we present a record of storm18 triggered turbidite deposition offshore the Dry Tortugas, south Florida, USA, that spans 19 abrupt transitions in North Atlantic sea-surface temperature and Atlantic Meridional 20 Overturning Circulation (AMOC) during the Younger Dryas (12.9–11.7 k.y. B.P.). 21 Despite potentially hostile conditions for cyclogenesis in the tropical North Atlantic at 22