erratic

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erratic

a piece of rock that differs in composition, shape, etc., from the rock surrounding it, having been transported from its place of origin, esp by glacial action

erratic

[ə′rad·ik]
(geology)
A rock fragment that has been transported a great distance, generally by glacier ice or floating ice, and differs from the bedrock on which it rests.
References in periodicals archive ?
Freek Rhebergen (Emmen) discusses Baltic Ordovician sponges (Porifera) recovered from erratic boulders in Neogene fluvial deposits of The Netherlands and northern Germany.
Zeles, Latvia)--was undertaken to date deposits and landforms of the Scandinavian ice sheet in Belarus, Poland, Lithuania, Latvia, and Estonia, mainly by dating key organic-bearing units by AMS radiocarbon and erratic boulders on moraine surfaces using cosmogenic nuclides ([sup.
The middle, most argillaceous part of the Vormsi Stage contains the endemic saukrodictyid brachiopod Hulterstadia cor (Wiman), known previously only from erratic boulders on the Island of Oland (Sweden) (Wiman 1907; Harper 2000).