Multibeam data from both troughs show subglacial features extending across the shelf, indicating that the WAIS grounded at depths over 1000 m. The multibeam data record erosional grooves on the inner shelf and mega-scale glacial lineations extending across the outer shelf. Like other areas with crystalline bedrock, the ice did not flow directly offshore but rather followed the structural grain of the area. Flow within that portion of the ice sheet grounded on the outer shelf was directed offshore. In both areas the transition between the crystalline and sedimentary substrate is delineated by a change from grooves to mega-scale glacial lineations.
Small drumlins occur at the crystalline-sedimentary bed transition.
Eltanin Bay is a broad bay located in the Bellingshausen Sea west of the Abbot Ice Shelf and east of the Ronne Entrance. Multibeam data reveal a large trough extending across the shelf. The data show erosional grooves in the inner portion of the bay. Farther offshore, mega-scale glacial lineations characterize the geomorphology. No data were collected from the outer shelf due to severe weather conditions.