Diamicton
Unlithified, poorly sorted sediment containing a broad range of grain and clast sizes; the term itself does not specify depositional origin.
Language and route: Modern sedimentological coinage. A modern technical compound employing Greek diá ‘through’ and miktós ‘mixed’. It describes texture rather than requiring a particular depositional agent.
Literal gloss: Thoroughly mixed
The name and its history
Term family: Flint, Sanders & Rodgers (1960); exact first coiner of *diamicton* unresolved · 1960 for *symmicton/symmictite* and *diamictite*; earliest *diamicton* not established
- What does the word literally mean?
- A modern scientific compound from Greek diá ‘through, throughout’ and miktós ‘mixed’; it describes poorly sorted mixed sediment without asserting glacial deposition.
- What did the original author mean?
- Flint, Sanders and Rodgers proposed the nongenetic words symmicton and symmictite in 1960 for mixed, unsorted sediments and rocks; in a second 1960 paper they expressly substituted diamictite for symmictite. It is unsafe to claim that the exact word diamicton first appeared in that same paper without checking it.
- Why was the name needed?
- Sedimentologists needed to describe deposits resembling glacial till without prematurely assuming glacier transport or origin; this was particularly consequential for claims of ancient glaciations.
- What evidence supported the original concept?
- The 1960 Geological Society of America Bulletin article describes unconsolidated sediment as symmicton, consolidated rock as symmictite; the subsequent note is titled Diamictite, a substitute term for symmictite. Later authors sometimes retrospectively attribute the whole diamict vocabulary to 1960.
- How has geology changed the concept?
- Modern usage commonly distinguishes unconsolidated diamicton from lithified diamictite, while using diamict more generally. These are textural, not glacial-genetic, names; their lexical chronology cannot be reconstructed by treating all three forms as identical.
Further historical context
Flint, Sanders and Rodgers in 1960 wanted to replace the implicit glacier hypothesis contained in ‘tillite’ when sorting and matrix were observable but origin was not. Their first paper used symmicton for sediment and symmictite for rock; later that year they published Diamictite, a substitute term for symmictite.
Subsequent literature adopted diamict, diamicton (unconsolidated) and diamictite (lithified). Later sources disagree about when the precise form diamicton became established; an earliest printed citation remains unverified.
Modern IODP field guidance retains this important lithification distinction and treats both terms as nongenetic. This is an example where careless citation of the term family hides an actual history of scientific revision.
Editorial qualification
Corrected false equivalence of the 1960 coinage diamictite with an independently verified first appearance of diamicton. The latter's first use remains open; the need for a nongenetic descriptive term is securely documented.
Related names
Sources
- Geological Digressions: diamict — Etymology and terminology
- IODP Expedition 400 methods — Nongenetic definition and diamictite distinction
- British Geological Survey: diamictite vocabulary — Lithified equivalent
- Flint, Sanders & Rodgers (1960), *Diamictite* (bibliographical identification) — Contemporaneous proposal of root term *diamictite*, not proof of first *diamicton*
- Ocean Drilling Program, use of non-genetic diamicton — Modern description independent of depositional mechanism
- Flint, Sanders & Rodgers (1960a), Symmictite and symmicton — Original naming of symmicton/symmictite, preceding the word diamictite
- Flint, Sanders & Rodgers (1960b), Diamictite, a substitute term — Original publication of the replacement name diamictite; not proof of first diamicton