What do they do when they are touring the Grand Canyon, or Glacier National Park, or the Gunnison Black Canyon, and they read the information board about the ancient geology of those places?
For background info, consider the Young Earth theory, in which an earth much younger than mainstream sciences thinks it to be had its antediluvian land masses shaped by Noah's flood. That is, the 80% of the earth's land that is currently covered by sedimentary layers had those deposits laid down in a short time, some say one year, and that all the major geological features were created during that time period.
The Young Earth theory, originally conceived, I believe, in the 1600's, modified and then mostly dropped in the 1800's, saw a partial resurgence of adherents in the early 1900's and then really began to catch on with Christian fundamentalists with the rise of that movement.
Or, do they even really wonder about it?