Characterizing the Geomorphology of Richardson ‘Jellyfish’ Scarp on the Blake Plateau, Southeast U.S. Continental Margin

The Richardson Hills Region of the southeastern U.S. continental margin’s Blake Plateau was explored during two NOAA Ocean Exploration and Research (OER) expeditions on board the NOAA Ship Okeanos Explorer: Windows to the Deep 2018 and 2019. Each expedition’s goal was to map and gather information of seafloor characteristics and identify potential deep-sea coral and sponge habitats. The purpose of this study was to characterize the geomorphology of a northwestern section of the Blake Plateau referred to as the Richardson Hills Region, located approximately 250 km east of Hilton Head Island, South Carolina, where depths range from 400 to 950 m. Multibeam sonar data collected during cruise EX1805 were used to produce bathymetric, backscatter intensity and slope surfaces of the seafloor which reveal a nearly circular basin surrounded by flat lying strata. The basin’s scarp is composed of hard substrate, and has a steep incline of approximately 50°, with a vertical relief of nearly 250 m. During Windows to the Deep 2019, NOAA OER explored the scarp, nicknaming it Richardson "Jellyfish," using the ROV Deep Discoverer to capture high definition video of the geomorphologic features, as well as thriving benthic habitats. This study uses the EX1805 bathymetric data and EX1903 high definition video to characterize the Richardson “Jellyfish” Scarp’s geomorphology, as well as the geomorphology of the benthic habitats.