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[1] Ninetyeast Ridge (NER) is a linear volcanic ridge in the Indian Ocean thought to have formed by hotspot volcanism on the northward-drifting Indian plate. Geological data from the ridge are sparse, so its tectonic evolution is poorly known. We studied satellite-derived gravity data, seismic reflection profiles, and multibeam bathymetry to examine NER structure. Gravity data show that the ridge displays a series of nearly E-W trending lineations with average spacing ∼0.4°(45 km). In seismic and bathymetry data, these lineations correlate with horsts and grabens that probably formed near the time of ridge emplacement. From their extensional nature and trends, we infer that these faulted structures formed near the spreading ridge that separated the Indian and Antarctic plates and their ubiquity implies the hotspot was never far from this spreading ridge.

A broad region, nearly the size of the Mediterranean Sea, exists in the central South Pacific Ocean that is devoid of sediment and has been so since the Late Cretaceous. The requirements for remaining sediment free are very low biological productivity, a shallow calcite compensation depth, essentially no dust input, and no deposition of hydrothermal oxides and hydroxides. One or two of these conditions are common, but nowhere else do all four occur. The combined effect of these sediment-inhibiting factors is a consequence of crustal age, seawater chemistry, and atmospheric, oceanographic, and physiographic isolation. Furthermore, this unique combination of conditions has prevailed for more than 80 million years.

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Coastal Louisiana received significant funds tied to BP penalties as a result of the Deepwater Horizon incident. As it is widely considered that the State of Louisiana sustained most of the damage due to this incident, there has been a firm push to waste no time in implementing habitat restoration projects. Sustaining the land on the coast of Louisiana is vital to our nation’s economy, as several of the nation’s largest ports are located on the Gulf coast in Louisiana. In addition, the ecosystems making up the Louisiana coast are important to sustain some of the largest and most valuable fisheries in the nation. Funded by BP Phase 3 Early Restoration, the goals of the Natural Resource Damage Assessment (NRDA) Outer Coast Restoration Project are to restore beach, dune, and marsh habitats to help compensate spill-related injuries to habitats and species, specifically brown pelicans, terns, skimmers, and gulls. Four island components in Louisiana were funded under this project; Shell Island Barrier Restoration, Chenier Ronquille Barrier Island Restoration, Caillou Lake Headlands Barrier Island Restoration, and North Breton Island Restoration (https://www. gulfspillrestoration.noaa.gov/louisiana-outer-coast-restoration, NOAA 2018). Shell Island and Chenier Ronquille are critical pieces of barrier shoreline within the Barataria Basin in Plaquemines Parish, Louisiana. These large-scale restoration projects were completed in the years following the Deepwater Horizon incident, creating new habitat and reinforcing Louisiana’s Gulf of Mexico shoreline. The Louisiana Coastal Protection and Restoration Authority (CPRA) finished construction of the Shell Island NRDA Restoration Project in 2017, which restored two barrier islands in Plaquemines Parish utilizing sand hydraulically dredged from the Mississippi River and pumped via pipeline over 20 miles over levees and through towns, marinas, and marshes to the coastline. The National Marine Fisheries Service (NMFS) also completed the Plaquemines Parish barrier island restoration at Chenier Ronquille in 2017 utilizing nearshore Gulf of Mexico sediment, restoring wetland, coastal, and nearshore habitat in the Barataria Basin. A design and construction overview is provided herein.