Gregg's research has applications both in predicting the behavior of lava flows on Earth and in assessing the make-up of lava flows on other planets. During her Alvin dives, Gregg saw lava flows as well as crabs along the East Pacific Rise, a volcanically active area off the coast of Mexico. If Gregg sees a mussel while cruising the sea floor, it's a clue that she may find a volcanic vent nearby. I don't think there's any other place on Earth where it's quite so clear how much the biology and the geology tell the same story. It's all intertwined.
Life colonizes around the chemical-rich warm water provided by the lava flows.
When lava erupts on the sea floor, it heats up the surrounding water. Deposits of sulfur and other minerals also build up around vents, just like they do around the geysers at Yellowstone National Park. The difference is, sulfur forms the base of the food chain on the sea floor. During her on-location work, Gregg almost literally got a taste of the sulfur while spending four hours helping to sort a large sample of mussels for another researcher. The sulfur smell was so strong, it just made your eyes water and your mouth burn.