Presentation by Dominic Comley
 What are Fossils
 The word fossil literally means “dug up”
 Fossils consist of prints or preserved remains of living
o...
 How do fossils form?
 Fossilisation requires the following conditions, rapid and
permanent burial which protects the sp...
A fish that has just spawned dies and sinks to
the ocean floor.
After sometime the fish begins to decay and
is covered wit...
Over time the skeleton is gradually buried
deeper. Slowly the weight of the sediment
compacts, pressing the grains togethe...
Millions of years may pass and the rock
remains buried deep within the bedrock;
however the collision between
neighbouring...
An example of what the palaeontologist may find when searching
for fossils.
Mold (imprint) fossils: When a leaf, feather, bone or even a body of an
organism leaves an imprint on sediment, which
hard...
Fossil fuels: Fuels formed by the remains of dead plants and animals,
such as oil, coal or gas for example
Actual remains:...
The fifth and final form of fossil is.
Petrified wood: When minerals replace wood or stone
to create either petrified wood...
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Introduction to fossils

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Introduction to fossils

  1. 1. Presentation by Dominic Comley
  2. 2.  What are Fossils  The word fossil literally means “dug up”  Fossils consist of prints or preserved remains of living organisms  Such a definition includes our prehistoric human ancestry and the ice age fauna such as mammoths for example; as well as more ancient fossil groups such as the dinosaurs, ammonites and trilobites.
  3. 3.  How do fossils form?  Fossilisation requires the following conditions, rapid and permanent burial which protects the specimen from environmental or biological disturbance including oxygen deprivation which limits the extent of decay and also biological activity such as scavenging; continued sediment accumulation as opposed to an eroding surface - ensuring the organism remains buried in the long-term; and the absence of excessive heating or compression which might otherwise destroy it.  Water plays a crucial role in fossilisation as it is almost always involved in the process, even fossils found on land such as those of dinosaurs, were ultimately preserved in sediments deposited beneath water for example in wetlands, lakes, rivers, estuaries or swept out to sea.  The fossilisation process will be further discussed, through the use of an example of how a fish ends up being a fossil.
  4. 4. A fish that has just spawned dies and sinks to the ocean floor. After sometime the fish begins to decay and is covered with a layer of sediment, rapidly entombing the fish. This may be caused by a landslide or earth quakes experienced at the bottom of the ocean. Once entombed, bacteria eat away that the decomposing flesh, leaving behind only the skeleton.
  5. 5. Over time the skeleton is gradually buried deeper. Slowly the weight of the sediment compacts, pressing the grains together, driving excess water out, and depositing minerals in the pores, and ultimately turning the soft sediment to hard rock - a process known as lithification. As this process takes place, minerals contained within the sediment replace the original minerals in the skeleton and fill any voids formed as parts of the skeleton dissolve. This process of mineral replacement is known as permineralisation and results in a remineralised copy of the original skeleton.
  6. 6. Millions of years may pass and the rock remains buried deep within the bedrock; however the collision between neighbouring continental plates buckle and uplift the bedrock, raising it above sea level and exposing it to erosion. Slowly, rock is stripped away, until eventually the top of the fish's skull is visible at the surface. If lucky palaeontologist may stumble upon the remains of the fish in its fossilised form, the extraction process is painstakingly slow, and a generous amount of rock is retained around the fossil as to protect the specimen.
  7. 7. An example of what the palaeontologist may find when searching for fossils.
  8. 8. Mold (imprint) fossils: When a leaf, feather, bone or even a body of an organism leaves an imprint on sediment, which hardens and becomes rock Types of fossils Cast fossils: When minerals fill in the hollows of an animal track, a mollusk shell, or another part of an organism
  9. 9. Fossil fuels: Fuels formed by the remains of dead plants and animals, such as oil, coal or gas for example Actual remains: The body of an organism, with all the parts intact. Usually preserved in ice, amber, or tar.
  10. 10. The fifth and final form of fossil is. Petrified wood: When minerals replace wood or stone to create either petrified wood or a mineralized fossil

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