What are fossils?
- remains of living organisms
- hard parts of whole or fragmented organisms e.g. shells
- trace fossils include burrows, tracks and trails
Factors that affect fossilisation!
S - size of sediment
T - transport distance
A - amount of oxygen
R - rapidity of burial
D - diagenesis
O - original composition
E - energy levels
Size of sediment = fine sediments preserves organisms better than coarse sediment.
Transport distance = fossils are transported during transport, due to abrasions or collisions causing breakage
Amount of Oxygen = accelerates breakdown of the organisms due to the bacterial decay and encourages scavenges
Rapidity of burial = faster burial means more chance of better preservation and less chance of scavengers eating them
Diagenesis = the changes within sediment after burial, the composition and acidity of the percolating ground water is important, as it may dissolve or replace the fossil with another mineral
Original composition = calcite or aragonite which can be altered easily. hard parts made of silica, such as radiolaria and some sponges may be preserved unaltered
Energy Levels = high energy produces lots of fragments; low…