No comprehensive scheme yet exists to describe the depositional products of submarine sediment failures at the scale of piston cores, resulting in misinterpretation of failure deposits and overuse of the genetic term ‘debris flow’. Ninety‐nine sediment cores (0·5 to 20 m in length), from offshore eastern Canada and the Gulf of Mexico, are used to propose a descriptive sedimentary facies scheme with genetic implications for mass‐transport deposits. Seven facies are distinguished: (i) allochthonous stratified sediment; (ii) distorted stratified sediment; (iii) clast‐supported hard‐mud‐clast conglomerate; (iv) matrix‐supported mud‐clast conglomerate; (v) thin mud‐clast conglomerate (<0·8 m thick); (vi) diamicton; and (vii) sorted sand‐gravel deposits (≥0·05 m thick). Seven genetic types of deposits are recognized. (i) Slumping of coherent sediment blocks (facies I). (ii) Slump and slide deposits (facies I and II). (iii) Debris‐avalanche deposits (hard sediment of facies I and II overlain by facies III). (iv) Low‐viscosity or large‐scale, high‐viscosity, cohesive debris flow deposits (facies IV, may have I, II, and III). (v) Very low‐viscosity debris flow deposits (facies V). (vi) Cohesionless debris flow deposits (facies VI). (vii) High‐density turbidity currents (facies VII). Vertical transitions between the genetic types were analysed by Markov chain analysis. Although sedimentological transitions are inferred between deposits of slides and cohesive debris flows, their spatial distribution indicates that a cohesive debris flow forms principally in the initial stages of a sediment failure, suggesting that transformation depends mostly on the strength of the sediments. A genetic link is suggested for cohesionless debris flow deposits, which originate from the disintegration of sandy sediment on the upper continental slope, and the closely related turbidity current deposits. Debris avalanches are common in sedimentary marine environments with steep slopes (>10°). In many cases, geometrical and seismic characteristics of debris avalanche, slide and debris flow are similar, requiring core data to verify transport process.

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Mass transport deposits, up to 3·9 m thick, have been identified from piston cores collected from canyon floors and inter‐canyon ridges on the central Scotian Slope. These deposits are characterized by four distinct mass‐transport facies – folded mud, dipping stratified mud, various types of mud‐clast conglomerate, and diamicton. Commonly, the folded and stratified mud facies are overlain by mud‐clast conglomerate, followed by diamicton and then by turbidity current deposits of well‐sorted sand. Stratified and folded mud facies were sourced from canyon walls. Overconsolidation in clasts in some mud‐clast conglomerates indicates that the source sediment was buried 12–33 m, much deeper than the present cored depth, implying a source in canyon heads and canyon walls. The known stratigraphic framework for the region and new radiocarbon dating suggests that there were four or five episodes of sediment failure within the past 17 ka, most of which are found in more than one canyon system. The most likely mechanism for triggering occasional, synchronous failures in separate canyons is seismic ground shaking. The facies sequence is interpreted as resulting from local slides being overlain by mud‐clast conglomerate deposits derived from failures farther upslope and finally by coarser‐grained deposits resulting from retrogressive failure re‐mobilizing upper slope sediments to form debrisflows and turbidity currents.

Quantitative X-ray diffraction (qXRD) mineralogy of bedrock, ice-rafted, and fluvial clasts, 239 seafloor samples (<2 mm), and samples from two long piston cores were used to (i) define regional patterns and sources within Baffin Bay, (ii) evaluate two areas from west Greenland and east Baffin Island in more detail, and (iii) apply these findings to the interpretation of downcore variations in sediment sources. A sediment-unmixing program is used to define surface regional mineral assemblages and to examine changes in sediment sources in cores HU2013029-77PC (southern Baffin Island slope) and HU2008029-8PC (Davis Strait) during Marine Isotope Stages 1 through 3. Distinct regional patterns are observed in the association between the mineralogy of surface sediments and carbonate and basalt bedrock outcrops. Detailed analysis of seafloor samples from the west Greenland troughs and Baffin Island fjords show regional differences in mineralogy, with sediments derived from the Foxe Fold Belt (north-central Baffin Island) being mineralogically distinct from sediments to the north and south. Grain-size spectra from the west Greenland troughs suggested an association between grain-size spectra and mineral assemblages. Sediment unmixing of qXRD data from the two piston cores shows discrete intervals where one or more mineral sources were dominant. However, chronological control is such that it is unclear whether the various ice streams draining into Baffin Bay behaved synchronously.