Reading up on some of the hydrothermal literature I came across this graphic comparing a hydrothermal mound on the Mid-Atlantic Ridge to Duke University Chapel. The article is
Van Dover, C. L. (1995), Ecology of Mid-Atlantic Ridge hydrothermal vents, in Hydrothermal Vents and Processes, pp. 257-294, Geological Society Special Publication, No. 87.
The Caption Reads:
Fig. 5. Schematic illustration of a Snake Pit mound. Active chimneys are located at the top of the mound. The sides of the mound are steep and end in an apron of hydrothermal sediment and talus at the base. The Duke University Chapel is drawn to scale. From Karson & Brown (1988).