Graduation date: 1981

No description available.

No description available.

Bibliography: pages 45-55. / Eleven gravity cores from the continental margin off Eire and Land's End (SW England) were examined and found to document the major trends of the Late Pleistocene climate. Several stratigraphic indicators; - carbonate content, sediment texture, grain size, composition, nature of terrigenous components, ice-rafted debris and foraminiferal diversity were examined and show that the glacial history of the study area can be closely correlated with the palaeoclimatic evolution of the adjacent European shelf. Sediments deposited during Late Pleistocene glacial conditions show the following characteristics when compared to the surface sediments deposited under Holocene interglacial conditions: an increase in the quantity of ice-rafted debris and percentage of mica, and a notable increase in the degree of frosting and pitting of the quartz grains. Overall grain size was finer resulting in a silty sediment package. Sedimentologically the cores fall into two groups (1 and 2). The major difference being that Group 1 (located on the Pendragon Escarpment) received increased quantities of fine silts from a 'shelf spill-over' mechanism operating on the Fastnet and Western Approaches Basins, during glacial regressions. All sediment samples displayed polymodal characteristics reflecting the interaction of several different physical processes e.g. ice-rafting, contour currents etc. Striking variations in the populations of planktonic foraminifera were noted, alternating between Arctic and Sub-Arctic assemblages, reflecting the waxing and waning of glacial activity. The coccolith-carbonate minima correlate with the Arctic-fauna maxima and the ¹⁸O/¹⁶O maxima of the oxygen-isotope curves. Foraminiferal-test analysis (ratio of whole foraminifera fragmented foraminifera) revealed that no correlation existed with any of the other parameters analysed. However, the cores were severely affected by the presence of bottom currents which were strong enough to remove the fragmented tests. Parallellaminated contourites and evidence of erosion were noted in all cores. Ten cores penetrated sediments deposited during the last glacial maximum of 20,000 B.P - 18,000 B.P. near the 75cm depth mark (Core 1865 was too short to reach such sediments). However sediments reflecting the 11,000 B.P glacial readvance, detected at around the 25cm mark, were not as clearly represented. Bioturbation has smoothed the climatic record throughout the lengths of these cores and has also suppressed the high-frequency oscillations (<10³ B.P).

Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Science. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: p. 333-347. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Science, 1982. / Microfiche copy available in Archives and Science / Vita. / Bibliography: leaves 217-223. / by Frances Luellen Stephenson Hotchkiss. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1980. / Microfiche copy available in Archives and Science. / Bibliography: leaves 206-211. / by Alexander N. Shor. / Ph.D.

Observations of wind speed and direction, air and sea temperature, and solar radiation were obtained from an array of buoys in JASIN. The observations were analyzed to show spatial and temporal variability. Spectra of wind speed and air and sea temperature were computed to illustrate the distribution of variance over periods ranging from 3.5 minutes to 40 days. When plotted on log-log graphs the spectral estimates generally decrease with increasing frequency with slopes between -3/2 and -2. Spectra of air and sea temperature have a peak at the diurnal frequency. When plotted in variance-preserving form, the spectrum of wind speed is consistent with a spectral gap and is qualitatively similar to other observations of low frequency spectra. On the basis of a cross-correlation analysis, it appears that mesoscale eddies propagated with the mean wind speed except during frontal passages. Based on the cross-correlation between wind speed and air temperature, there is evidence of horizontal roll vortices or organized convection. / Graduation date: 1980

No description available.

No description available.