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Deep gravel-pit exposures reveal the distribution and structure of till and underlying sand and gravel in drumlins near Waukesha, Wisconsin. The subglacial sediment is interpreted to have moved laterally into the drumlin sites because the till thickens from the margin to the core of the drumlins, the stone orientation in the till is perpendicular and oblique to ice flow on the drumlin margins, and recumbent isoclinal folds occur in sand on the drumlin margins with axes parallel to the drumlin axes. The resulting accumulations of sediment presented obstacles to ice flow and were streamlined into the minimum-drag drumlin shape by erosion on the margins and by remolding of material in the core of the drumlins. These drumlin nuclei may have formed at spots where there was low effective stress on the bed. The subglacial sediment became mobile as a result of high pore pressure that may have developed as ground water and subglacial melt water were trapped behind a frozen bed at the ice margin. Under certain conditions, however, lateral sediment flow might also have occurred when the sediment was frozen.

Dielectric elastomer artificial muscles (electroelastomers) have been shown to exhibit excellent performance in a variety of actuator configurations. By rolling highly prestrained electroelastomer films onto a central compression spring, we have demonstrated multifunctional electroelastomer rolls (MERs) that combine load bearing, actuation, and sensing functions. The rolls are compact, have a potentially high electroelastomer-to-structure weight ratio, and can be configured to actuate in several ways including axial extension and bending, and as multiple degree-of-freedom (DOF) actuators that combine both extension and bending. 1-DOF, 2-DOF, and 3-DOF MERs have all been demonstrated through suitable electrode patterning on a single monolithic substrate. The bending MER actuators can act as leg and knee joints to produce biomimetic walking that is adaptable to many environments. Results of animation and the fabrications of a robot model of a synthetic bug or animal based on the MERs are presented. A new concept for an antagonist actuator for more precise control is introduced.

No abstract

Deposits of at least three glaciations are present in New Jersey and the New York City area. The oldest deposits are magnetically reversed. Pollen and stratigraphic relations suggest that they are from the earliest Laurentide advance at ~2.4 Ma. Deposits of a second advance are overlain by peat dated to 41 ka and so are pre-Marine Isotope Stage (pre-MIS) 2. Their relation to marine deposits indicates that they predate MIS 5 but postdate MIS 11 and may postdate MIS 7 or 9, suggesting an MIS 6 age. The most recent deposits are of MIS 2 (last glacial maximum [LGM]) age. Radiocarbon dates and varve counts tied to glacial-lake events indicate that LGM ice arrived at its terminus at 25 ka, stood at the terminus until ~24 ka, retreated at a rate of 80 m/yr until 23.5 ka, and then retreated at a rate of 12 m/yr to 18 ka. At 18 ka the retreat record connects to the base of the North American Varve Chronology at Newburgh, New York. The 25–24 ka age for the LGM is slightly younger than, but within the uncertainty of, cosmogenic ages; it is significantly older than the oldest dated macrofossils in postglacial deposits in the region.