Nappe
Large sheet-like body of rock transported tectonically away from its original position, commonly on thrust faults.
Language and route: English borrowing of French nappe, sheet or tablecloth, used in Alpine geological structural interpretation. English borrowing of French nappe, sheet or tablecloth, used in Alpine geological structural interpretation
Literal gloss: sheet / tablecloth
The name and its history
Alpine structural school including Bertrand, Schardt and Lugeon · concept in 1880s; specific first use of word unverified
- What does the word literally mean?
- Immediate linguistic pathway: English borrowing of French nappe, sheet or tablecloth, used in Alpine geological structural interpretation. Relevant original form: nappe (nappe); conventional gloss ‘sheet / tablecloth’. The linguistic gloss should not be mistaken for the original scientist’s stated motive unless directly demonstrated.
- What did the original author mean?
- Alpine geologists recognised that huge tracts of apparent stratigraphic cover could be sheets displaced from elsewhere, contrary to in-place folding explanations.
- Why was the name needed?
- To represent anomalous superposition and large lateral transport in complex mountain belts at the regional map scale.
- What evidence supported the original concept?
- Stratigraphic inversion, displaced contacts, structural windows and klippen, remote lithologic correspondence.
- How has geology changed the concept?
- Modern nappes encompass thrust sheets and transported tectonostratigraphic packages; early models based on unfolding recumbent folds were only one possible mechanism.
Further historical context
Alpine geologists recognised that huge tracts of apparent stratigraphic cover could be sheets displaced from elsewhere, contrary to in-place folding explanations.
To represent anomalous superposition and large lateral transport in complex mountain belts at the regional map scale.
Stratigraphic inversion, displaced contacts, structural windows and klippen, remote lithologic correspondence.
Modern nappes encompass thrust sheets and transported tectonostratigraphic packages; early models based on unfolding recumbent folds were only one possible mechanism.
Editorial qualification
Bertrand 1884 is a historical conceptual milestone, NOT securely first coinage of the word nappe.
Related names
Sources
- The history of Alpine thrust nappes — academic book sample — Historical interpretation of Bertrand 1884 and later Alpine work; PDF excerpt not page inspected
- BGS Loch Eriboll field guide — origin of thrust and mylonite — Historic sequence; Geikie thrust 1884, Lapworth mylonite 1885
- Dewey & Bird (1970), Mountain belts and the new global tectonics — Contemporary plate-tectonic mountain-belt synthesis; not verified term coining