Fossils are the remains of ancient animal and plants preserved in any form (remnants or impressions) by the natural men in the sedimentary rocks or rarely in swamps, in tar pits or in frozen ice. Fossils are classified as (i) original fossil, (ii) frozen fossil, (iii) petrified fossil and (iv) moulds ,casts and prints.
Formation of Fossils:
- Original Fossils: Hard parts like skeleton, teeth or shells are buried and preserved.
- Frozen Fossils: Whole body buried under thick ice deposit and remains unchanged.
- Petrified Fossil: Less permanent parts are preserved by replacement of organic parts by mineral deposits the process being called petrification.
- Wings, skin, leaves even footprints leave their impressions on mud or soft soil and the latter is converted to rock.