fossils are the remains of organisms from many thousands of years ago which are found in rocks. they provide evidence for that organisms liked ages ago
what are the 3 ways fossils are formed?
-gradual replacement by minerals
-casts and impressions
-preservation
what is gradual replacement?
things like bones don't decay easily are eventually replaced by minerals forming a rock like structure shaped like the original part
what is cast and impressions?
when an organism is buried in a soft material which later hardens around it and the organism decays leaving a cast
when the materials are soft things like footprints can be pressed into it leaving an impression when it hardens
what is preservation?
this where no decay happens eg. glaciers to cold for decay microbes to work
