The rise of fundamentalist Christianity at the start of the 20th century saw a renewed interest in proposals that the Earth was thousands of years old, as a part of the movement's rejection of evolution.

In 1923, George Mc Cready Price, a Seventh-day Adventist, wrote The New Geology, a book partly inspired by the book Patriarchs and Prophets in which Seventh-day Adventist prophet Ellen G.

In the 1950s, Price's work came under severe criticism, particularly by Bernard Ramm in his book The Christian View of Science and Scripture. Laurence Kulp, a geologist and in fellowship with the Plymouth Brethren, and other scientists, Ramm influenced Christian organizations such as the American Scientific Affiliation (ASA) in not supporting flood geology. Given this history, they argued, "the last refuge of the case for evolution immediately vanishes away, and the record of the rocks becomes a tremendous witness...

Price's work was subsequently adapted and updated by Henry M. to the holiness and justice and power of the living God of Creation!

As these processes were very gradual, the Earth needed to be ancient, in order to allow time for the changes to occur.

While his ideas of Plutonism were hotly contested, scientific inquiries on competing ideas of catastrophism pushed back the age of the Earth into the millions of years – still much younger than commonly accepted by modern scientists, but a great change from the literalist view of an Earth that was only a few thousand years old.

Since the mid-20th century, young Earth creationists—starting with Henry Morris (1918–2006)—have devised and promoted a pseudoscientific explanation called "creation science" as a basis for a religious belief in a supernatural, geologically recent creation.

Harold Camping for example dated the creation to 11,013 BC, while Christian Charles Josias Bunsen in the 19th century dated the creation to 20,000 BC.

Proposed calculations of the date of creation, using the Masoretic from the 10th century – 18th century include: Marianus Scotus (4192 BC), Maimonides (4058 BC), Henri Spondanus (4051 BC), Benedict Pereira (4021 BC), Louis Cappel (4005 BC), James Ussher (4004 BC), Augustin Calmet (4002 BC), Isaac Newton (4000 BC), Johannes Kepler (27 April, 3977 BC) [based on his book Mysterium], Petavius (3984 BC), Theodore Bibliander (3980 BC), Christen Sørensen Longomontanus (3966 BC), Melanchthon (3964 BC), Martin Luther (3961 BC), John Lightfoot (3960 BC), Cornelius Cornelii a Lapide (3951 BC) Joseph Justus Scaliger (3949 BC), Christoph Helvig (3947 BC), Gerardus Mercator (3928 BC), Matthieu Brouard (3927 BC), Benito Arias Montano (3849 BC), Andreas Helwig (3836 BC), David Gans (3761 BC) and Gershom ben Judah (3754 BC).

Among the Masoretic creation estimates or calculations for the date of creation Ussher's specific chronology dating the creation to 4004 BC became the most accepted and popular, mainly because this specific date was attached to the King James Bible.

In particular, discoveries in geology required an Earth that was much older than thousands of years, and proposals such as Abraham Gottlob Werner's Neptunism attempted to incorporate what was understood from geological investigations into a coherent description of Earth's natural history.

James Hutton, now regarded as the father of modern geology, went further and opened up the concept of deep time for scientific inquiry.