Solved cryptogram
Uranium decays so slowly that much of what was here when Earth formed has yet to break down.
Chemistry Facts, sourced to Royal Society of Chemistry.
What it means
The common isotope has a half life close to the age of the Earth itself, so a little under half of the original stock is still sitting in the rocks. That slow, steady decay is also a clock. Comparing uranium with the lead it turns into is how the age of the Earth was first established at roughly four and a half billion years, and the method has held up.
The claim comes from Royal Society of Chemistry, and the page it comes from was read on 2026-08-27 to confirm it still says this.
This is not the kind of claim that goes out of date, which is why it was set as a puzzle rather than a fact with a shelf life.
Solve it yourself
This fact is a cryptogram here: 74 letters over 19 different ones, graded medium.
- SourceRoyal Society of Chemistry
- CollectionChemistry Facts
- Difficultymedium
- Length74 letters, 19 of them different
Nearby in the collection
The facts either side of this one.
- Royal Society of Chemistrymedium, 77 letters
- Royal Society of Chemistryhard, 75 letters
- Royal Society of Chemistrymedium, 74 letters
- U.S. Geological Surveyhard, 73 letters
About as hard as this one
Scored closest to it by the model behind our guide to solving cryptograms.
- Royal Society of Chemistrymedium, 70 letters
- Royal Society of Chemistrymedium, 68 letters
- Royal Society of Chemistrymedium, 79 letters
- Royal Society of Chemistrymedium, 77 letters