The document discusses the various types of fossils, including compression fossils, impression fossils, and petrifactions, explaining their formation processes and characteristics. It highlights the significance of fossils in geological studies, particularly in biostratigraphy, which helps determine the ages of rocks. Additionally, it outlines how environmental factors and conditions affect fossilization.

1. Fossils and Their
Types
Uswa Hasna
BS_4
Department of botany
Lahore college for women university

2. •Fossils
•The remains of plants and
•Fossil record:
•The data recorded in fossils,
the fossil record.

3. How Fossil formed?
Fossilization
Decomposition
Formation of sediments
Fossil

4. Factors effecting fossilization process
The nature of plant or animal material
The kind of entombing material.
The rapidity with which the plant was covered and
thus prevented from exposure to organism of decay.
The condition of plant material at the time of
fossilization

5. Compressions:
A compression fossil is a fossil preserved in
sedimentary rock
 It is very common to find plants preserved this way.
The best sediment that have been compressed in
compression is the fossils of leaves.
 Plant stems and other three-dimensional plant
structures do not preserve as well under compression.
Compression fossils are formed most commonly in
environments where fine sediment is deposited, such
as in river deltas, lagoons, along rivers, and in ponds.

6. Impressions or imprints:
The sediments around the compressed
plants or plant part become hardened and
form a three-dimensional mold.
They only reveal the outline of the plant
and its parts. The cellular details are not
preserved.
They are regarded as the negatives of the
compressions.
Impression fossils form when a leaf, shell,
skin, or foot. leaves an imprint in soft
earth.

7. Petrifactions:
• The replacement of the original
material and the filling of the original
pore spaces with minerals.
• Petrifaction takes place by two
processes
I. Permineralization
II. replacement.
• They are the best type of fossils.
• They reveal the internal structure of
the part of the plant which is petrify.

8. Types of fossils
•Following are different kinds of fossils.
Dead and preserved Bodies:
The actual dead and preserved bodies of
plants and animals or parts of bodies are
preserved in rock or ice.
The original tissues remain intact in the
fossilized material.

9. Encrustation fossils:
• They found in hot springs whose water
contain abundant mineral matter.
• The fallen twigs, leaves, spores, algae
and bacteria live in such hot springs
become coated with carbonates and are
encapsuled.
• These carbonates become precipitated
on cooling.

10. Calcification:
• This process is used by some
algae.
• They secrete a heavy coat of
calcium carbonate around
them.
• Coral reef found in the oceans
are built more by secretion of
calcium carbonate by marine
algae rather than by corals.

11. Diatomaceous earth:
• These regions were earlies inundated by the
oceans that were inhabited by countless
members Diatoms
• Diatoms are a silicon-based algae.
• After the death of these diatoms, their
siliceous shell sank to the bottom of the sea.
• The mass of these shells went on
accumulating at the bottom for million of
years and formed the diatomaceous earth.

12. Actual remains:
 These are young age fossils which don’t
decompose due to low temperature or
vacuum.
 All materials are preserved e.g., cuticle,
cutin, walls of pollen grains and spores.
Chemical remains:
 Chemical materials like amino acid and
hydrocarbons may be obtained in a natural
state from the rocks.
 Organ of plant has been incorporated in this
chemical material.

13. How do fossils help geologists?
Some key origins and changes in fossil organisms through
geological time; these changes help geologists determine the
ages of rocks.
Biostratigraphy:
This use of fossils to help understand the age of rocks is called
biostratigraphy.

14. Thank You