112219c

Intraclasts. Particles ripped loose from the seafloor or wherever they might be, and redeposited in essentially the same unit where they first formed.

Mixed particle grainstone, dominated by crinoid debris, bryozoan fragments, intraclasts, and mud. It is not clear whether the mud was deposited after the particles were already in place, consists almost entirely of parts of intraclasts, and/or may have been deposited under the influence of microbes. Thin-section photomicrograph, 2.5 mm wide.

Same field of view, with three arrows pointing to three intraclasts. One intraclasts contains a large crinoid columnal and the other two contain other kinds of particles. It could be that the one pointed to by the white arrow is itself part of a larger and younger intraclast containing many fossil fragments.

Tropical shallow-marine platform environment. Relatively slow deposition and rapid lithification on the seafloor produced abundant intraclasts. Mississippian Bangor Limestone, Blount County, Alabama.