Mere (lake)

Mere in English refers to a lake that is broad in relation to its depth, e.g. Martin Mere. A significant effect of its shallow depth is that for all or most of the time, it has no thermocline.

The word mere is recorded in Old English as mere ″sea, lake″, corresponding to Old Saxon meri, Old Low Franconian *meri (Dutch meer ″lake, pool″, Picard mer ″pool, lake″, Northern French toponymic element -mer), Old High German mari / meri (German Meer ″sea″), Goth. mari-, marei, Old Norse marr ″sea″ (Norwegian mar ″sea″, Shetland Norn mar ″mer, deep water fishing qarea″, Faroese marrur ″mud, sludge″, Swedish place name element mar-, French mare ″pool, pond″). They derive from reconstituted Proto-Germanic *mari, itself from Indo-European *mori, the same root as marsh and moor. The Indo-European root *mori gave also birth to similar words in the other European languages : Latin mare ″sea″ (Italian mare, Spanish mar, French mer), Old Celtic *mori ″sea″ (Gaulish mori-, more, Irish muir, Welsh môr, Breton mor), Old Slavic morje.

The word once included the sea or an arm of the sea in its range of meaning but this marine usage is now obsolete (OED). It is a poetical or dialect word meaning a sheet of standing water, a lake or a pond (OED). The OED's fourth definition ("A marsh, a fen.") includes wetland such as fen amongst usages of the word which is reflected in the lexicographers' recording of it. In a quotation from the year 598, mere is contrasted against moss (bog) and field against fen. The OED quotation from 1609 does not say what a mere is, except that it looks black. In 1629 mere and marsh were becoming interchangeable but in 1876 mere was 'heard, at times, applied to ground permanently under water': in other words, a very shallow lake. The online edition of the OED's quoted examples relate to:

Where land similar to that of Martin Mere, gently undulating glacial till, becomes flooded and develops fen and bog, the remnants of the original mere remain until the whole is filled with peat. This can be delayed where the mere is fed by lime-rich water from chalk or limestone upland and a significant proportion of the outflow from the mere takes the form of evaporation. In these circumstances, the lime (typically calcium carbonate) is deposited on the peaty bed and inhibits plant growth therefore peat formation. A typical feature of these meres is that they are alongside a river rather than having the river flowing through them. In this way, the mere is replenished by seepage from the bed of the lime-rich river, through the river's natural levée, or by winter floods. The water of the mere is then static through the summer, when the concentration of the calcium carbonate rises until it is precipitated on the bed of the mere.

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