• Sedimentary rocks cover  some  80  percent  of  the  earth’s  crust.  All  our  knowledge of  stratigraphy,  and  the  bulk  of  our  knowledge  of  structural  geology  are  based  on studies  of  sedimentary  rocks.
  • Sedimentary rocks of the geological record were deposited in the whole range of natural environments that exist today. The study of these modern environments and their sediments and processes contributes much to the understanding of their ancient equivalents