In order to better define the late Eocene clinopyroxene-bearing (cpx) spherule layer and to determine how the ejecta vary with distance from the presumed source crater (Popigai), we searched for the layer at 23 additional sites. We identified the layer at six (maybe seven) of these sites: Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) Holes 592, 699A, 703A, 709C, 786A, 1090B, and probably 738B. The cpx spherule layer occurs in magnetochron 16n.1n, which indicates an age of ca. 35.4 ± 0.1 Ma for the layer. We found the highest abundance of cpx spherules and associated microtektites in Hole 709C in the northwest Indian Ocean, and we found coesite and shocked quartz in the cpx spherule layer at this site. We also found coesite in the cpx spherule layer at Site 216 in the northeast Indian Ocean. This is the first time that coesite has been found in the cpx spherule layer, and it provides additional support for the impact origin of this layer. In addition, the discovery of coesite and shocked quartz grains (with planar deformation features [PDFs]) supports the conclusion that the pancake-shaped clay spherules associated with quartz grains exhibiting PDFs are diagenetically altered cpx spherules. An Ir anomaly was found associated with the cpx spherule layer at all four of the new sites (699A, 709C, 738B, 1090B) for which we obtained Ir data. The geometric mean of the Ir fluence for the 12 sites with Ir data is 5.7 ng/cm 2 , which is ~10% of the fluence estimated for the Cretaceous-Tertiary boundary. Based on the geographic distribution of the 23 sites now known to contain the cpx spherule layer, and 12 sites where we have good chronostratigraphy but the cpx spherule layer is apparently absent, we propose that the cpx spherule strewn field may have a ray-like distribution pattern. Within one of the rays, the abundance of spherules decreases and the percent microtektites increases with distance from Popigai. Shocked quartz and coesite have been found only in this ray at the two sites that are closest to Popigai. At several sites in the Southern Ocean, an increase in δ 18 O in the bulk carbonate occurs immediately above the cpx spherule layer. This increase may indicate a drop in temperature coincident with the impact that produced the cpx spherule layer.

The records of glaciation and climate change preserved in sediments on the Canadian and northwest Greenland margins of Baffin Bay pertaining to the last interglacial-glacial transition are remarkably similar. In both regions, warmer than present terrestrial and nearshore marine facies of the last interglacial sensu stricto (s.s.) are overlain by glacial sediments that represent the most extensive advance of continental ice during the last glaciation. Chronometric controls ( 14 C, thermoluminescence, amino acids) indicate an isotope stage 5 age for this advance. Evidence for extensive high-latitude glacial erosion during stage 5 is recorded by abundant pre-Quaternary palynomorphs in Baffin Bay sediment cores, in contrast to a much reduced flux during the remainder of the last glaciation. Warm nearshore marine conditions (seasonally ice free) also occurred near the end of stage 5 along both the eastern Baffin Island and northwest Greenland coasts after the maximum glacial advance; surface water in central Baffin Bay apparently was dominated by meltwater at this time. Subsequently (isotope stages 4, 3, and 2), terrestrial conditions were colder and drier, sea-surface temperatures were lower, and ice margins were retracted. Minimum summer insolation at high latitudes, coupled with mild winters and vigorous meridional oceanic (and presumably atmospheric) circulation characterized the inception phase of the last glaciation during isotope stage 5. In contrast, the 20 ka B.P. (isotope stage 2) “last glacial maximum” was characterized by a zonal circulation regime that resulted in cold and dry conditions over Baffin Bay; the margins of the northwest Greenland and northeast Laurentide ice sheets did not extend beyond the fiords at this time.