EESA06H3 Lecture 8: Lecture 8
Document Summary
A very short history of life on earth. Shells buried and preserved unaltered (<100 million years) Cavities filled with silica, calcium carbonate, iron j a process called mineralization: minerals come from water that flows through the rocks and gets trapped in the cavity. Freezing: not common at all but is the best methods. Amber tarpits: e. g. tree saps that preserves and insect in it. Carbonization: when only the carbon is left from the decay. Sedimentation (fine grained = more detail; chemical makeup of rock = colour: e. g. clay preserves more details that sand, e. g. if a lot of iron, fossil may be red. More sediments pile on = pressure = rock. Mineral rich water = changes to the shell. Erosion: when eroded, fossils will be seen. E. g. ammolite: an organic gemstone, very colourful. Iridescent aragonite with trace elements (fe, mn, al, ba)
