Tropically-driven climate shifts in southwestern Europe during MIS 19, a low eccentricity interglacial

The relative roles of high- versus low-latitude forcing of millennial-scale climate variability are still not well understood. Here we present terrestrial–marine climate profiles from the southwestern Iberian margin, a region particularly affected by precession, that show millennial climate oscillations related to a nonlinear response to the Earth's precession cycle during Marine Isotope Stage (MIS) 19. MIS 19 has been considered the best analogue to our present interglacial from an astronomical point of view due to the reduced eccentricity centred at 785 ka. In our records, seven millennial-scale forest contractions punctuated MIS 19 superimposed to two orbitally-driven Mediterranean forest expansions. In contrast to our present interglacial, we evidence for the first time low latitude-driven 5000-yr cycles of drying and cooling in the western Mediterranean region, along with warmth in the subtropical gyre related to the fourth harmonic of precession. These cycles indicate repeated intensification of North Atlantic meridional moisture transport that along with decrease in boreal summer insolation triggered ice growth and may have contributed to the glacial inception, at ∼774 ka. The freshwater fluxes during MIS 19ab amplified the cooling events in the North Atlantic promoting further cooling and leading to MIS 18 glaciation. The discrepancy between the dominant cyclicity observed during MIS 1, 2500-yr, and that of MIS 19, 5000-yr, challenges the similar duration of the Holocene and MIS 19c interglacials under natural boundary conditions.

Astronomical time scale for Paleocene and early Eocene sediments

The astronomical-tuned time scale is rapidly extended into the Paleogene but, due to the existence of an Eocene gap, different tuning options had to be presented for the Paleocene. These options differ both in number and tuning of ~405-kyr eccentricity related cycles and are only partially consistent with recalculated 40Ar/39Ar constraints for the Cretaceous/Paleogene (K/Pg) and Paleocene/Eocene (P/E) boundaries. In this paper, we evaluate the cyclostratigraphic interpretation of records from ODP Leg 198 and 208 sites, and the Zumaia section to solve the problem of the different tuning options. We found that the interval between the K/Pg boundary and the early Late Paleocene biotic event (ELPE) comprises 17 instead of 16 * ~405-kyr eccentricity related cycles as previously proposed, while the entire Paleocene contains 25 * ~405-kyr cycles. Starting from 40Ar/39Ar age constraints for the K/Pg boundary, a new tuning to 405-kyr eccentricity is presented for the Paleocene and earliest Eocene, which results in ages of ~66.0 and ~ 56.0 Ma for the K/Pg and P/E boundaries, respectively. This tuning introduces considerable differences in age for a number of nannofossil events at ODP Sites 1209 and 1262 in the interval between 61 and 63 Ma, but eliminates large and abrupt changes in the seafloor spreading rate. The tuning seems further consistent with recalculated 40Ar/39Ar ages for ash layer -17 of early Eocene age. However, despite this apparent consistency with existing radio-isotopic constraints, an alternative 405-kyr younger or, less likely, older tuning cannot be excluded at this stage.

The Scientific results from the orbiting astronomical observatory (OAO-2),

"Proceedings of a symposium sponsored by the National Aeronautics and Space Administration and the American Astronomical Society held in Amherst, Massachusetts, August 23-24, 1971."

Outline for field work in geography /

Reprinted from the Bulletin of the American geographical society, v. 47, July, 1915.

Sunday reading for christian families and individuals : containing short commentaries, scripture histories, geography ... sacred poetry /

Includes bibliographical references.

Geography; or, A description of the world.

Mode of access: Internet.

Dar es Salaam; a study in urban geography.

Bibliographical footnotes.

Handbook of the linguistic geography of New England,

Issued as part of the author's Linguistic atlas of the United States and Canada.

A complete treatise on the geography of Ireland, on a new plan, never before attempted by any writer.

Mode of access: Internet.

Material on geography which may be obtained free or at small cost /

Includes bibliographical references (p. 45-51, 54-60).

Geography of New Zealand.

Mode of access: Internet.

A geography of South America : including the West Indies /

First edition published 1901.

Studies in Byzantine astronomical terminology.

"A simple list of technical terms, their meaning being determined by their usage in Cod. Vat. gr. 1058, fol. 261 to 459."

Handbook of the linguistic geography of New England /

Supplements the Linguistic atlas of New England.

Plant-geography upon a physiological basis ...

Includes bibliographies.