ALBERT

Description: Firm stratigraphic correlations are needed to evaluate the global significance of unconformity bounded units (sequences). We correlate the well-developed uppermost Campanian and Maestrichtian sequences of the New Jersey Coastal Plain to the geomagnetic polarity time scale (GPTS) by integrating Sr-isotopic stratigraphy and biostratigraphy. To do this, we developed a Maestrichtian (ca. 73-65 Ma) Sr-isotopic reference section at Deep Sea Drilling Project Hole 525A in the southeastern Atlantic Ocean. Maestrichtian strata can then be dated by measuring their 87Sr/86Sr composition, calibrating to the GPTS of S. C. Cande and D. V. Kent (1993, personal commun.), and using the equation Age (Ma) = 37326.894-52639.89 (87Sr/86Sr). Sr-stratigraphic resolution for the Maestrichtian is estimated as +-1.2 to +-2 m.y. At least two unconformity-bounded units comprise the uppermost Campanian to Maestrichtian strata in New Jersey. The lower one, the Marshalltown sequence, is assigned to calcareous nannofossil Zones CC20/21 (~NC19) and CC22b (~NC20). It ranges in age from ~74.1 to 69.9 Ma based on Sr-isotope age estimates. The overlying Navesink sequence is assigned to calcareous nannoplankton Zones CC25-26 (~NC21-23); it ranges in age from 69.3 to 65 Ma based on Sr-isotope age estimates. The upper part of this sequence, the Tinton Formation, has no calcareous planktonic control; Sr-isotopes provide an age estimate of 66 +- 1.2 Ma (latest Maestrichtian). Sequence boundaries at the base and the top of the Marshalltown sequence match boundaries elsewhere in the Atlantic Coastal Plain (Owens and Gohn, 1985) and the inferred global sea-level record of Haq et al. (1987); they support eustatic changes as the mechanism controlling depositional history of this sequence. However, the latest Maestrichtian record in New Jersey does not agree with Haq et al. (1987); we attribute this to correlation and time-scale differences near the Cretaceous/Paleogene boundary. High sedimentation rates in the latest Maestrichtian of New Jersey (Shrewsbury Member of the Red Bank Formation and the Tinton Formation) suggest tectonic uplift and/or rapid progradation during deposition of the highstand systems tract.

Description: The ‘law of the wall’ for the inner part of a turbulent shear flow over a solid surface is one of the cornerstones of fluid dynamics, and one of the very few pieces of turbulence theory whose results include a simple analytic function for the mean velocity distribution, the logarithmic law. Various aspects of the law have recently been questioned, and this paper is a summary of the present position. Although the law of the wall for velocity has apparently been confirmed by experiment well outside its original range, the law of the wall for temperature seems to apply only to very simple flows. Since the two laws are derived by closely analogous arguments this throws suspicion on the law of the wall for velocity. Analysis of simulation data, for all the Reynolds stresses including the shear stress, shows that law-of-the-wall scaling fails spectacularly in the viscous wall region, even when the logarithmic law is relatively well behaved. Virtually all turbulence models are calibrated to reproduce the law of the wall in simple flows, and we discuss whether, in practice or in principle, their range of validity is larger than that of the law of the wall itself: the present answer is that it is not; so that when the law of the wall (or the mixing-length formula) fails, current Reynolds-averaged turbulence models are likely to fail too.