dropstone

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dropstone

[′dräp‚stōn]
(geology)
A rock that was carried by a glacier or iceberg, and deposited as the ice melted.
References in periodicals archive ?
However, few dropstones ([less than or equal to] 6 cm in diameter) of crystalline rocks were found in these sediments.
Nevertheless, occasional dropstones in the clay rhythmites of SU1 indicate that deposition from the bottom of the glacier which ran over or floated above the deep valley at Arumetsa may have taken place during Late Saalian time.
When he presented a paper in 1963 on a "Great Infra-Cambrian Glaciation" he was shot down by critics who interpreted his glacial dropstones as products of marine mudslides.
They lack graded beds and coarse silt and sand strata that often characterize glacial lake sediments (varves) and have a low percentage of dropstones.
1996), and Martin (1999), these clasts are interpreted as ice-rafted dropstones.
A lack of seasonal lamination and the presence of ice-rain deposits with dropstones suggest that the WGD was mostly deposited by subaquatic basal meltout and the massive fine-grained sediment settled as suspension fall-out (Fig.
6 million years ago, these cruises found evidence for a latest-Miocene to earliest-Pliocene ice advance: 4- to 6-million-year-old glacial dropstones have been recovered from both the North Atlantic and North Pacific oceans.
Scientists have found similar dropstones in Cretaceous deposits from the Northern Hemisphere, and the rocks also are found in sediments from other warm periods.
1999a), most of Unit 1 likely consists of silty mud with scattered angular grit and dropstones, and was deposited by meltwater plumes and icebergs emanating from Late Wisconsinan ice.