Pollen and macrofossils profiles and age determination from three cores in Northeastern Kansas, U.S.A.

Two marshes near Muscotah and Arrington, Atchison County, northeastern Kansas, yielded a pollen sequence covering the last 25,000 yrs of vegetation development. The earliest pollen spectra are comparable with surface pollen spectra from southern Saskatchewan and southeastern Manitoba and might indicate a rather open vegetation but with some pine, spruce, and birch as the most important tree species, with local stands of alder and willow. This type of vegetation changed about 23,000 yrs ago to a spruce forest, which prevailed in the region until at least 15,000 yrs ago. Because of a hiatus, the vegetation changes resulting in the spread of a mixed deciduous forest and prairie, which was present in the region from 11,000 to 9,000 yrs ago, remain unknown. Prairie vegetation, with perhaps a few trees along the valleys, covered the region until about 5,000 yrs ago, when a re-expansion of deciduous trees began in the lowlands.

Categorización fonológica por infantes de 9 a 12 meses de edad aprendices del español : Laboratorio de Infantes, Facultad de Psicología, Universidad Nacional Autónoma de México

Los infantes se sensibilizan a los patrones fonológicos más constantes en el lenguaje del ambiente, aun antes de que hagan su primera asociación referencial entre los sonidos de las palabras y los significados. Esta sensibilización promueve el desarrollo de ha- bilidades perceptuales para la adquisición del lenguaje. El objetivo de este estudio fue evaluar en infantes aprendices del español, las habilidades para categorizar fonológicamente palabras por la coincidencia en el inicio o final de las mismas. Usando el Procedimiento de Atención Preferencial Auditiva, se realizaron dos experimentos con infantes de 9 a 12 meses de edad. Los participantes escuchaban dos tipos de listas de palabras CVCV. Las palabras en las listas experimentales coincidían en una sílaba en particular (i.e. inicial, Experimento 1; final, Experimento 2), mientras que las palabras en las listas control no tenían regularidad alguna. Los resultados revelaron que, a pesar de la variabilidad en su sílaba contigua, los infantes aprendices del español categorizan tanto palabras que tienen un inicio en común, como aquellas que coinciden en la sílaba final. Dadas las características morfológicas del español, se discute su relación con el desarrollo de estas habilidades perceptuales

Benthic foraminiferal carbon isotopic records and the development of abyssal circulation at DSDP Sites 9-77, 12-119, 30-289, 82-563 and 94-608

The North Atlantic at present is ventilated by overflow of the Denmark Strait, Iceland-Faeroe Ridge, Faeroe Bank Channel, and Wyville-Thompson Ridge. The evolution of Cenozoic abyssal circulation of this region was related to tectonic opening and subsidence of these sills. We used d13C records of the benthic foraminifer Cibicidoides to decipher the timing of tectonically controlled changes in bottom-water circulation in the eastern basins (Biscay and Iberian) of the northern North Atlantic. Records from Site 608 (Kings Trough, northeastern North Atlantic) show that from about 24 to 15 Ma (early to early middle Miocene), d13C values in the Kings Trough area were depleted relative to western North Atlantic values and were more similar to Pacific d13C values. This reflects less ventilation of the Kings Trough region as compared to the well-oxygenated western North Atlantic. Comparison of Oligocene d13C records from Site 119 (Bay of Biscay) with western North Atlantic records suggests that the eastern basin was also relatively isolated prior to 24 Ma. At about 15 Ma, d13C values at Site 608 attained values similar to the western North Atlantic, indicating increased eastern basin ventilation in the middle Miocene. This increased advection into the eastern basin predated a major d18O increase which occurred at about 14.6 Ma. Subsidence estimates of the Greenland-Scotland Ridge indicate that the deepening of the Iceland-Faeroe Ridge was coincident with the marked change in eastern basin deep-water ventilation.