This image is an illustration based on a photograph of the cave formation known as the Fountain of Youth in Stark Caverns, Eldon, Missouri.
The description states:
FOUNTAIN OF YOUTH, STARK CAVERNS
HIGHWAY 54 — ELDON, MISSOURI
One of the truly different type formations found in Stark Caverns. A fine example of water cutting through solid limestone depicting the effects of erosion — a marvel of mother nature. Thousands drink from this fountain each year.
–The attraction has been renamed Fantasy World Caverns. This feature was constructed from a flowing spring in the cave to create a large pool with a controlled outflow.
This image likely dates from the 1940s.