出典:Wiktionary
出典:Wikipedia
出典:『Wikipedia』 (2010/11/04 23:47 UTC 版)
Bioclasts are skeletal fragments of marine or land organisms that are found in sedimentary rocks laid down in a marine environment—especially limestone varieties, some of which take on distinct textures and coloration from their predominate bioclasts—that geologists, archaeologists and paleontologists use to date a rock strata to a particular geological era.