Poster Number 203
See more from this Division: Topical Sessions
See more from this Session: The Western Interior Seaway (Posters)
Abstract:
Measurements from the eastern Book Cliffs of channel dimensions within the Lower Castlegate (n = 140) and the Grassy Mbr of the Blackhawk Fm (n = 43) reveal similar values for maximum average channel depth between the two fluvial systems: 4.2 m and 4.7 m, respectively. The systems also exhibit comparable ranges for individual channel depths, 0.8-18.4 m for the Lower Castlegate and 0.9-14.6 m for the Grassy. Maximum observed channel depths within the Lower Castlegate and Grassy were 4.3 and 3.1 times the average channel depth, respectively; in agreement with scour-depth relationships seen in modern rivers. This set of comparable dimensional data is consistent with unchanging paleo-discharges for river channels of the upper Blackhawk and Lower Castlegate systems. However, the difference in net-to-gross indicates that Lower Castlegate rivers were more effective at distributing sand throughout the system and transporting mud out of the system. Pending work will combine grain-size data with the channel-depth data in order to characterize the paleo-hydraulics and paleo-gradients of the Lower Castlegate and Grassy fluvial systems and to assess the degree of environmental similarity between the two depositional systems.
See more from this Division: Topical Sessions
See more from this Session: The Western Interior Seaway (Posters)