Varve
annual layer of sediment or sedimentary rock

A varve is an annual layer of sediment or sedimentary rock.
The word 'varve' derives from the Swedish word varv whose meanings and connotations include 'revolution', 'in layers', and 'circle'.
Of the many rhythmites in the geological record, varves are one of the most important and illuminating in studies of past climate change. Varves are amongst the smallest-scale events recognised in stratigraphy.
An annual layer can be highly visible because the particles washed into the layer in the spring when there is greater flow strength are much coarser than those deposited later in the year. This forms a pair of layers—one coarse and one fine—for each annual cycle. Varves form only in fresh or brackish water, because the high levels of salt in normal sea water coagulate the clay into coarse grains. Since the saline waters leave coarse particles all year, it is nearly impossible to distinguish the individual layers in salt waters. Indeed, clay flocculation occurs at high ionic strength due to the collapse of the clay electrical double layer (EDL), which decreases the electrostatic repulsion between negatively charged clay particles.
Etymology
The word 'varve' derives from the Swedish word varv whose meaning and connotations include 'revolution', 'in layers', and 'circle'.
This brief starts where responsible research should: with the source description of “Varve” as annual layer of sediment or sedimentary rock. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the general reference register because the source frames it as annual layer of sediment or sedimentary rock. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Sep 12, 2026. The linked authority identifier is Q835591. None of the 0 selected statements returned an explicit reference.
The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “Varve” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.