Preservation of fossils

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…