ABSTRACTDated mollusc collections are classified in assemblages to map paleo-faunistic zones. Hiatella arctica and Mya truncata account for almost half the records and comprise a restricted arctic assemblage. Arctic assemblages comprise 70% and arctic-dominated assemblages 80% of the database. Fifteen species dominate but 170 taxa are recorded. At last glacial maximum, the arctic zone extended from the Arctic Ocean to the Grand Banks. The boreal zone in the western Atlantic was compressed. The subarctic zone, which today dominates eastern Canada, was small. The boreal zone was extensive in the eastern Pacific where subarctic and arctic zones were compressed. Zones shifted northward during deglaciation and the arctic zone diversified when Bering Strait submerged 10.5-10.3 ka BP. Western Arctic molluscs during Younger Dryas time indicate shallow waters warmer than present. Major North Atlantic currents were established 9.5-9.0 ka BP. The subarctic zone extended to the head of Baffin Bay and a boreal zone became established in West Greenland 9-8 ka BP, with intensive changes about 8.5 ka BP. We relate the latter to the reduction of Mackenzie River discharge and in sea ice export to the North Atlantic as Laurentide ice withdrew from Mackenzie headwaters. The extended subarctic zone in Baffin Bay persisted until 3 ka BP and then retreated about 1000 km on the Canadian side. Boreal-subarctic molluscs in the Gulf of St. Lawrence before 9.5 ka BP derived from the glacial refugium. High boreal-subarctic molluscs farther north probably migrated from Europe. We postulate that the Labrador Current acts as a one-way valve for mollusc migrations at glacial-interglacial scales.

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15Claims of CO 2 leakage at the Kerr farm near the IEAGHG Weyburn-Midale CO 2 Monitoring and Storage 16 project in Saskatchewan, Canada in 2011 presented an opportunity to test years of research in near-17 surface leakage detection in an operational setting. The claim was based on a study conducted by a private 18 consultant that drew criticism from geologic CO 2 storage experts. To assess the origin of the claimed 19 leakage, a soil gas assessment was conducted at the site using a relatively new process-based soil gas 20 approach (Romanak et al., 2012). In order to assess leakage without years of background data or complex 21 statistical analyses, this simple approach uses three fixed soil gas ratios (augmented by isotopic and 22 hydrocarbon data when needed). Using this approach at the Kerr site, the relative contributions of various 23 processes creating soil gas geochemical signatures were determined including: 1) biologic respiration, 2) 24 CH 4 oxidation, 3) CO 2 dissolution/reaction with carbonate, 4) mixing with atmosphere, and 5) CO 2 25 leakage from the storage reservoir. For additional verification, the results of the Kerr assessment were 26 compared to new data collected at the ZERT controlled release site in Bozeman, Montana and published 27 data from a leakage proxy at the Mt. Etna volcano, Italy. The results from the Kerr site show no evidence 28 for CO 2 leakage from the storage reservoir and also verify that a process-based approach can be used to 29 quickly and economically assess leakage above geologic carbon storage sites. In addition, data from the 30 ZERT release suggest quantification of a leakage signal apart from natural processes may be most easily 31 accomplished using a process-based approach.

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Wide, boulder-strewn intertidal flats occur around the head of Frobisher Bay and along parts of the shoreline of Cumberland Sound, in southeast Baffin Island. The coastal environment is characterized by large tidal ranges, severe winter sea ice conditions, and a relative sea level history which involves rapid and then decreasing land emergence during the earlier part of the Holocene, succeeded by slight recent submergence. Summer field investigations were carried out at two sites, Koojesse Inlet on Frobisher Bay, where ice breakup conditions were also monitored, and Pangnirtung Fiord off Cumberland Sound. The results are summarized under three headings: physical and biological zonation across the tidal flats; tidal action and sea ice processes; and geological evolution of the tidal flats. Comparisons are made with similar settings described by others in Labrador and Ungava Bay. The sedimentary shores at both Baffin Island sites exhibit a distinct physical zonation, most evident in the concentration of boulders in the middle tidal flat zone at Koojesse Inlet and in the boulder barricade at the seaward margin of the Pangnirtung flats. Biological observations show a zonation of intertidal flora and fauna across the intertidal zone at Koojesse Inlet. An outstanding problem concerns the mode of transport of very large boulders. Pushing and rolling, by ice floes which are confined to the intertidal zone by the solid ice in the offshore zone during the critical early phase of breakup may be more appropriate processes than ice rafting.