Publications

No abstract available.

Seismic profiles, drill core samples, and gravity data suggest that a complex impact crater ~35.5 million years old and 90 kilometers in diameter is buried beneath the lower Chesapeake Bay. The breccia that fills the structure contains evidence of shock metamorphism, including impact melt breccias and multiple sets of planar deformation features (shock lamellae) in quartz and feldspar...

Four box cores and one piston core show that Holocene sedimentation on the southern Canada Abyssal Plain for the last 8010 ± 120 yr has consisted of a continuing rain of pelagic organic and ice-rafted clastic sediment with a net accumulation rate during the late Holocene of ⩽10 mm/1000 yr, and episodically emplaced turbidites 1–5 m thick deposited at intervals of 830 to 3450 yr (average...

The Whittier Narrows earthquake of 1987 and the Northridge earthquake of 1991 highlighted the earthquake hazards associated with buried faults in the Los Angeles region. A more thorough knowledge of the subsurface structure of southern California is needed to reveal these and other buried faults and to aid us in understanding how the earthquake-producing machinery works in this region.

Nine seismic-reflection profiles and four continuous core holes define the gross structural and stratigraphic framework of the outer rim of the Chesapeake Bay impact crater. The rim is manifested as a 90 km diameter ring of terraced normal-fault blocks, which forms a ∼320 m–1200 m high rim escarpment. The top of the rim escarpment is covered by a 20 m–30 m thick ejecta blanket. The...

Elevation differences on the order of 10 cm within Florida's marsh system influence major variations in tidal flooding and in the associated plant communities. This low elevation gradient combined with sea level fluctuation of 5-to-10 cm over decadel and longer periods can generate significant alteration and erosion of marsh habitats along the Gulf Coast. Knowledge of precise and...

We use three-dimensional elastic models to help guide the kinematic interpretation of crustal deformation associated with strike-slip faults. Deformation of the brittle upper crust in the vicinity of strike-slip fault systems is modeled with the assumption that upper crustal deformation is driven by the relative plate motion in the upper mantle. The driving motion is represented by...

A sea-floor mapping investigation designed to assess the sediment distribution, the movement of the nearshore sand supply, and the fate of sediment eroded from the shoreline was conducted using high-resolution sidescan-sonar, seismic reflection, and sediment sampling techniques on the northern insular shelf of Puerto Rico, off the town of Luquillo. Sea-floor structures and the...

The Sea of Galilee (Lake Kinneret) is located at the northern portion of the Kinneret-Bet Shean basin, in the northern Dead Sea transform. Three hundred kilometers of continuous marine gravity data were collected in the lake and integrated with land gravity data to a distance of more than 20 km around the lake. Analyses of the gravity data resulted in a free-air anomaly map, a variable...

A suite of 146 new accelerator-mass spectrometer (AMS) radiocarbon ages provides the first reliable chronology for late Quaternary sediments in Lake Baikal. In this large, highly oligotrophic lake, biogenic and authigenic carbonate are absent, and plant macrofossils are extremely rare. Total organic carbon is therefore the primary material available for dating. Several problems are...

No abstract available.

We have conducted a paleomagnetic study of sediment cores obtained from the Selenga prodelta region of Lake Baikal, Russia. This record, which spans approximately the last 84 kyr, contributes to a better understanding of the nature of geomagnetic field behavior in Siberia and is a useful correlation and dating tool. We demonstrate that the Lake Baikal sediments are recording variations...