Earth & SkyGreek → English
Isochron
/ˈaɪsə(ʊ)krɒn/noun
A line joining points of equal age or equal travel time, and in geochronology the plotted line whose slope gives a rock's age.
The Greek roots
ἴσος
ísos
equal, same
χρόνος
chrónos
time
Literally: “equal time”
The story of the word
Radiometric dating leans on it hard: samples from one rock that formed together fall on a straight line whose slope is the age, and scatter off the line is the signal that something has leaked. Cartographers use the same word for lines of equal journey time from a city, which is why a commuting map and a uranium-lead plot share a name. Isochronous, meaning taking equal time, is the older sibling, used of pendulums since the seventeenth century.
- How it travelled
- Ancient Greek → scientific coinage → English
- First recorded
- 19th century
Same family
chronologychronicanachronismisobarsynchronise
In a sentence
Five samples plotted on the isochron and gave an age of 2.7 billion years.
The commuter isochrons bulge along the rail lines.