Atlantic 231Pa/230Th and biogenic opal compilation of the Holocene and the LGM

The strength and geometry of the Atlantic meridional overturning circulation is tightly coupled to climate on glacial-interglacial and millennial timescales, but has proved difficult to reconstruct, particularly for the Last Glacial Maximum. Today, the return flow from the northern North Atlantic to lower latitudes associated with the Atlantic meridional overturning circulation reaches down to approximately 4,000 m. In contrast, during the Last Glacial Maximum this return flow is thought to have occurred primarily at shallower depths. Measurements of sedimentary 231Pa/230Th have been used to reconstruct the strength of circulation in the North Atlantic Ocean, but the effects of biogenic silica on 231Pa/230Th-based estimates remain controversial. Here we use measurements of 231Pa/230Th ratios and biogenic silica in Holocene-aged Atlantic sediments and simulations with a two-dimensional scavenging model to demonstrate that the geometry and strength of the Atlantic meridional overturning circulation are the primary controls of 231Pa/230Th ratios in modern Atlantic sediments. For the glacial maximum, a simulation of Atlantic overturning with a shallow, but vigorous circulation and bulk water transport at around 2,000 m depth best matched observed glacial Atlantic 231Pa/230Th values. We estimate that the transport of intermediate water during the Last Glacial Maximum was at least as strong as deep water transport today.

St.Francis Basin project (MO,AR) : environmental impact statement.

F available only in microfiche

Polio evaluation meeting, Dr. Thomas Francis, Jr., Dr. Jonas E. Salk

Announcement of success of the Salk polio vaccine following test trials at the University of Michigan

An historical discourse, on the two hundredth anniversary of the founding of the Hopkins grammar school, New Haven, Connecticut. Delivered before the "Hopkins grammar school association", July 24th, 1860 / by Leonard Woolsey Bacon. With notes and an appendix. Pub. by request of the Association.

Mode of access: Internet.

Conducting surveys for Davis-Bacon construction wage determinations: resource book /

"March, 1989"

A memoir of the life and labors of Francis Wayland ... late president of Brown University, including selections from his personal reminiscences and correspondence /

Mode of access: Internet.