In this study we report on the occurrence and potential significance of Atlantic sturgeon (Acipenser oxyrhynchus) feeding traces observed in the Bay of Fundy in great abundance on the intertidal mud flats of Mary's Point, New Brunswick, Canada. The traces comprise a crescent-shaped impression and a plug-shaped excavation and are considered to be a modern analogue for the trace fossil Piscichnus. Local areas exhibit relatively great numbers of the feeding structure: the sediment in these zones contains bivalves (primarily Macoma balthica), worms (generally nereid polychaetes), and amphipods (Corophium volutator). Analysis of the feeding-trace distribution and orientation shows that activity is greatest within 500 m of mean high water and coincides with the highest population densities of amphipods (up to 30,000 individuals per m 2 ). Where sturgeon feeding is most intense, voluminous quantities of clay and silt are redistributed. Within the study area, as much as 1,220 m 3 of intertidal sediment is resuspended during the 6 summer weeks that mark peak sturgeon activity. The reworked sediment contributes to the extensive soupy substrate, which accumulates from suspension deposition of silts and minor amounts of clay during slack tide. Subsequent to their excavation, feeding depressions trap sediment. Thus, feeding by the Atlantic sturgeon locally represents an important erosional-depositional agent in the intertidal mud flat zone within Mary's Point.

Quarry walls in Pleistocene marginal-marine coarse-grained deposits adjacent to Willapa Bay, Washington, expose a contact from which unusual sedimentary structures originate. These structures have two distinct occurrences: (1) vertical-to-subvertical columns where laminae and bedding deflect downward, and (2) normally graded beds with symmetric or asymmetric U-shaped structures with flared limbs. The scale, morphology, and distribution of the features suggest these are not physical sedimentary structures. Rather, they are more akin to biogenic sedimentary structures generated by the predatory action of marine animals on deep-burrowing bivalves. Several animals are known to forage sediment: elasmobranch fishes, fish, crabs, sea stars, sea otters, whales, and walruses. In particular, walruses generate distinctive excavations on the sea floor as they root for prey with their snouts and emit a jet of water that liquefies the bottom sediments where a bivalve has burrowed. The trace fossils reported likely represent the first examples of walrus feeding from the geologic record. Documentation in recent years of sea-floor furrows and pits on the Bering Shelf and Chukchi Sea produced by the Pacific Walrus (Odobenus rosmarus Linnaeus) provides modern analogues for the ancient trace fossils described from Willapa Bay. We present three significant implications from this comparison: (1) The method of hydraulic jetting employed by walruses for extraction of their prey leaves a distinctive trace fossil that can be used to identify the presence and activities of foraging walruses. (2) These predation structures are temporally significant in that they provide a minimum time of exposure and corresponding rate of accretion for the ancient estuary inlet. (3) Feeding excavations in paleo-Willapa Bay, Washington, were produced by walrus herds that wandered from the northern Pacific ice front during the Pleistocene after becoming barricaded from their present habitat in the Bering Shelf and Chukchi Sea.

The Falher "C" is a Lower Cretaceous transgressive-regressive sequence that contains mixed coarse-grained sandstone and conglomerate gas reservoirs in the Deep Basin of west-central Alberta. A total of 11 facies were identified in cored intervals of the Falher "C" and are further grouped into five facies associations representative of deposition in an offshoremarine through continental spectrum. Coarse-grained sandstone and conglomerate facies of high reservoir potential comprise facies association two (FA2), and were deposited within wave-dominated upper shoreface and foreshore settings. Finer grained non-reservoir facies (mudstone, siltstone, and fine-grained sandstone) were deposited within stormdominated lower shoreface (FA1), tidal inlet (FA3), back-barrier (FA4), and coastal plain (FA5) environments.Several significant stratigraphic surfaces have been utilized to further sub-divide the Falher "C" into three parasequences termed C1, C2, and C3. In ascending order of stratigraphic occurrence these surfaces are defined as i) TSE1, ii) RSE, and iii) TSE2. The lower and upper contacts of conglomerate-rich parasequence C2 correspond to a regressive surface of marine erosion (RSE), and the youngest transgressive surface of marine erosion (TSE2). From correlations made between cored intervals and calibrated well logs, it can be recognized that reservoir-quality conglomerates are stratigraphically restricted to Twp. 67.A paleogeographic model constructed for the Falher "C" demonstrates the distribution of important environments of deposition at four consecutive depositional intervals corresponding to distinct changes in sea level and sediment supply to the Falher shoreline. Initially, the shoreline underwent transgression in response to a relative rise of sea level whereupon parasequence C1 began to prograde northward. Transgression and progradation was followed by a relative fall of sea level and increased sediment supply that brought about a forced regression and deposition of the reservoir-bearing conglomeratic parasequence C2. Progradation of parasequence C3 was established shortly after a second period of transgression across the study area. Continued normal regression in response to progradation of parasequence C3 northward of the study area maintained aggradation of coastal-plain and deposition of the capping nonmarine C4 unit. The results of this study serve to enhance our present understanding of the scale, distribution, and three-dimensional predictability of conglomerate gas reservoirs in the Deep Basin of Alberta.

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