Due to the rough seas and remote location, the Southwest Indian Ridge was explored later than other ocean ridges. As a result, the rocks were described more carefully, following the new standards set by the Ocean Drilling Program, and rather than focusing nearly exclusively on the volcanic axis on the rift valley floor, sampling also systematically included the rift valley walls and fracture zones, where deep faulting brought mantle rock to the seafloor. The results for the 59,000 kg of rock recovered in 634 dredges show the mantle is exposed directly to the seafloor, often over vast regions where there is little or no crust. Since mantle rock is far more reactive than the basaltic ocean crust, the exchange of heat, mass, and volatiles between the Earth's interior, its oceans, and its atmosphere is likely dominated by seawater circulation directly into the mantle and back into the ocean. This has significant implications for both the biomass in the Earth beneath the southern ocean and for carbon sequestration, as the reactions produce both methane (food for life) and carbonate formed by capturing CO2 from the ocean.