remain of organisms from thousands of tears ago found in rocks
gradual replacement of minerals
teeth, shells, bones which dont decay
eventually replaced by minerals as they decay forming rock like substances
surrounding sedments also turn to rock but fossil stays distinct inside until discovered
casts and impressions
formed when an organism is buried in a soft material like clay which hardens around and organism decays leaving a cast of itself. the organism is then peserved
things like footprints can be pressedinto these matrials when soft leaving an impression when it hardens
preservations in places where no decay happens
in amber and tair pits theres no oxygen or moisture ao decay microbes cant survive
in glaciers its too cold for the decay microbes to work
