It could be the moon or some distant planet that Thomas Moran depicted in The Castle Geyser, so fantastical are the geological features of Yellowstone.¹ Geysers that shoot water hundreds of feet in the air, and the steam that rises from boiling cauldrons of sulfurous water suggest a place not of this world. Yet Moran’s use of soft pastels and rich jewel tones temper any of the more ominous aspects of the scene, transforming it into a wonderland. Moreover, the rainbow in the distance suggests a sense of hope and the promise of treasures to be found in this strange landscape.

Indeed, a century later, microbiologist Thomas Brock identified a bacterium, Thermus aquaticus, or Taq for short, which can live in the extreme heat of Yellowstone’s geothermal pools.² Biologists subsequently extracted an enzyme from Taq that was used by biochemist Kary Mullis to develop the polymerase chain reaction (PCR) process, a gene replicating tool. PCR is used in DNA profiling, which has revolutionized forensic medicine and led to major advancements in criminology. Astonishingly, less than one percent of the organisms in Yellowstone’s ten thousand geothermal features have been identified or even studied.³ We can only speculate as to what new discoveries and scientific advancements might be made in the future. Moran could not know what biological wonders would be found in Yellowstone, nor the benefits they could provide. Yet artworks such as The Castle Geyser continue to inspire our dreams and fuel our desire for knowledge of worlds unknown.

—Sandra Pauly, Henry Luce Foundation Curatorial Scholar for Moran Collection Research, 2021

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¹ The Castle Geyser is one of sixteen watercolors commissioned by a wealthy railroad investor, William Blackmore of England. Kinsey, Thomas Moran and the Surveying of the American West, 154. See also Hamber, Collecting the West, 151–52.
² Thomas Brock died on April 4, 2021. Taq has also been essential in developing the test for the coronavirus. For more, see his obituary in the New York Times, April 22, 2021; and Lisa Winter, “Microbiologist Thomas Brock Dies at 94,” The Scientist, April 23, 2021.
³ Schullery, Searching for Yellowstone, 1–5.