Earth & SkyGreek → English
Isopach
/ˈaɪsə(ʊ)pak/noun
A contour line joining points where a rock unit, ash layer or ice sheet has the same thickness.
The Greek roots
ἴσος
ísos
equal, same
πάχος
páchos
thickness
Literally: “equal thickness”
The story of the word
One of a large family of iso- lines that geologists and meteorologists built on the same template: isobars for pressure, isotherms for temperature, isohyets for rainfall, isopachs for thickness. An isopach map of a volcanic ash fall tells you where the vent was and how hard it blew, because the layer thins away from the source. Petroleum geologists read the same maps to work out how much rock a reservoir actually contains.
- How it travelled
- Ancient Greek → scientific coinage → English
- First recorded
- 20th century
Same family
isobarisothermisotopepachyderm
In a sentence
The isopachs close neatly around the caldera.
An isopach map of the coal seam settled where to sink the shaft.