There is today a great polarization among Christians in North America (and in cultures influenced by American Christian missions) about the validity of biological evolution.
Part of that polarization has to do with the age of the earth.
It turns out that most orthodox, evangelical Christians in the nineteenth century (and even in the first half of the twentieth century) accepted that Genesis was compatible with a very old earth (and universe).
This view that the earth was very old (millions of years) was a relatively new opinion, developed in response to recent understandings of the geological make-up of the earth. Prior to the rise of geological science, especially developments in the nineteenth century, no-one had any reason to think that the Bible was compatible with an old earth (just as prior to the Copernican Revolution in the sixteenth century, no one had any reason to think that the Bible was compatible with the earth revolving around the sun).
So in the nineteenth century, many quite orthodox Christians had come to accept the findings of geology and interpreted the Bible in ways consistent with an old earth (some even found ways of harmonizing the Bible with evolution; but that’s another story).
However, things changed significantly in the twentieth century. There was a retreat from science and a reversion to belief in a young earth (6,000-10,000 years old) among many American Christians.
Two of the main proponents of Young Earth Creationism (YEC) were Henry Morris and John C. Whitcomb Jr. They both tied their view of the age of the earth to what is known as Flood Geology (the idea that all the sedimentary strata in the earth, including all fossils, were laid down by the Noahic flood, and so were quite recent).
Both Morris and Whitcomb were influenced by George McCready Price, a Seventh Day Adventist (SDA) layman who wrote a famous pamphlet on the subject in 1906, entitled Illogical Geology: The Weakest Point in The Evolution Theory. Price’s ideas were based on the teachings of Ellen G. White, the founder of the SDA (who had claimed that God had showed her a vision of the Flood, in which the Grand Canyon was formed).
This, of course, is not an argument against Flood Geology; you shouldn’t critique a point of view based on its origins or because of those who hold the view (known as the genetic fallacy in logic).
Nevertheless, the story of how YEC (which was common before the nineteenth century), along with Flood Geology, came to prominence among twentieth-century American Christians is fascinating.
You might want to read about it here.