Abstract The Australian continental margin hosts numerous canyons. Some of the most spectacular canyons are located offshore Kangaroo Island, and these are linked to ancient courses of the River Murray, which would have flowed across the very wide Lacepede Shelf during periods of low sea level. During the AUSCAN-1 project, modern sedimentation was assessed using a multi-tracer approach on interface sediments from 350 to 2500 m water depth. The presence of freshly deposited particles, tagged by 234 Th in excess, 210 Pb-based sediment accumulation (0.03–0.13 cm a −1 ) and 230 Th-based focusing ratios, supports the occurrence of significant advection of marine sediments within these canyons. In the absence of direct riverine inputs, the shelf, being the site of intensive carbonate production, is the main supplier of material. The presence of incised channels in the eastern portion of the Murray Canyons Group (MCG) indicates recent to sub-recent activity along the canyons. The presence of underwater slides in the western side of the MCG confirms that sediment transport to the abyssal plain does occur. Based on our preliminary investigation and by synthesizing previous work on other canyons, we provide a conceptual model for sediment focusing and transfer within the canyons offshore Australia.

Abstract The Boulder Creek Watershed, within the Front Range region of Colorado, istypical of many western watersheds because it is composed of a high-gradient upperreach mostly fed by snowmelt, a substantial change in gradient at the range front, andan urban corridor within the lower gradient section. A stream ecosystem within anurban landscape not only can provide water for municipal, industrial, and agriculturalneeds, but also can be utilized for recreation, esthetic enjoyment, and wastewaterdisposal. The purpose of this 26 km bicycle field trip is to explore the hydrology andgeochemistry of Boulder and South Boulder Creeks and to discuss topics includingflood frequency and hazards, aqueous geochemistry of the watershed, and potentialimpacts of invasive species and emerging contaminants on stream ecology. Keywords: Colorado Front Range, flood hazard, water quality, invasive species