Sedimentary rock
Chalk
A soft, earthy, fine-textured limestone made of the tests of planktonic microorganisms.
Other sedimentary rocks
Conglomerate and breccia · Quartz arenite · Arkose · Lithic arenite · Wacke (greywacke) · Mudrocks: shale, mudstone, siltstone, claystone · Limestone · Coquina · Oolite · Travertine and tufa · Dolostone · Chert · Diatomite · Radiolarite · Evaporites: rock salt and gypsum · Banded iron formation · Coal: peat to anthracite · Oil shale