Very coarse grained fragmental rocks are defined as naturally formed aggregates of rocks and minerals containing >1% fragments between 0.256 m and 10 m (boulders) diameter. Because extremely large rock fragments may reach a maximum length of 100 km (tectonic plates), we introduce a size terminology to bridge a continuum(?) from sedimentary rocks to tectonically derived rocks. We propose extension of size terminology for fragments larger than boulder size—megaboulder, 10–100 m; block, 100–1000 m; megablock, 1–10 km—and tentatively suggest corresponding rock-assemblage names—megamictite, teramictite, and oromictite.

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