FOSSILS`

• Earth’s formation was thought to have started as a huge barren ball of ice and rock. It was devoid of atmosphere and oceans. Deep within the earth, however, radioactive elements gradually unleashed their power and, together with gravity, melted the rock which did not cool for the next hundred million years.

• According to this principle, if rock layers have not been overturned, the oldest layer is always at the bottom and the youngest on top.

•In many caves, groundwater seeps and drips constantly; The high the concentration of dissolved minerals in such water is left behind when the water drips and forms a thin crust onthe interior surface of the cave andwhatever lies In it. This will coat andpreserve any organism which dies here.

Organisms which have hardparts are preserved as the original material. This includesmany invertebrate shells composed of calcium phosphate.

•Tar pits are excellent sites for fossilization, vertebrate bones. Smaller pits have yielded perfectly preserved insects and even insectlarvae.

•Certain cone-bearing trees, such as spruce, pine, and fir, contain a sticky resinous sap which comes from woundsin the tree. Small insects and other minute organisms may become trapped in the resin, which, after burial may harden into amber.

•During the Pleistocene glaciation, when ice sheets covered much of the NorthernHemisphere, some animals like mammoths, Were trapped in permanently frozen soil.Some of these animals have been discovered perfectly preserved.

•In very arid regions, animals may dry out quickly and be preserved, soft parts and all.Ifugaos practice mummification with the death of their leader or loved ones.

Altered Remains

Lithification CarbonizationDissolution/Replacement

A process by which A process by which unconsolidated unconsolidated materials are are

transformed to transformed to solid rock bysolid rock by compaction.compaction.

A process by which A process by which unconsolidated unconsolidated materials are are

transformed to transformed to solid rock bysolid rock by compaction.compaction.

the process of dissolving

a solid substance into a solvent to yield a solution

the process of dissolving

a solid substance into a solvent to yield a solution

When organisms become mashed intothe sediment, their volatile componentsmay be forced out,leaving only a film

of carbon.

Trace Fossils

• Any reproduction of the anatomical featuresof the internal or external surface of an organism, animal tracks, or footprintspreserved in rocks may be termedexternal molds.

•This is in general, a duplication of the original. Casts are formed when originalparts are dissolved away and the resulting space filled either withsediment or mineral matter.

•These are smooth, polished stones that are often found in the abdominal cavities of the skeletons of dinosaurs. They are thought tohave helped those huge animals grind up vegetable matter in their stomachs.

• Fossil excrement can sometimes give definitive knowledge about the diet of the animal concerned.

•Rodents and other animals chew on bones for the calcium content anddid so in the past. Gnawed bones are frequently preserved as fossils.

•Certain worms and clams and many otherinvertebrates burrow into rocks, wood, shells,and all types of sediment. These burrowsare frequently preserved, especially in fine-grained rocks.

ModifiedModified TrueTrue or or FalseFalse.

1. The same forces acting on earth today are the same forces that shaped the earth throughout the history is known as principle of cross-cutting relationship.

2. Remains or traces of organisms that are not preserved in the earth’s crust is known as fossils.

3. Index fossils are used to establish the age of the rock that contain them.

4. Altered remains includes fossils which have undergone little or no change in structure and composition.

5. Replacement belongs to altered

remains.

BLOCKBLUSTERSBLOCKBLUSTERS

6. What OSM includes many invertebrate shells?

7. What IF is used to establish the age of rock?

8. What C explains that the sediment, the volatile components of an organism may be forced out, leaving only a film of carbon?

9. What C is a duplication of the original?

10.What PCR explains that the rock appears to cut across another is the younger rock?

11.What G are smooth and polished stones?

12.What C is a way to transform solid rocks?

13.What M is any reproduction preserved in rocks?

Write UR for unaltered remains, T for trace fossils and AR for altered remains in classifying the ff. terms.

1. Gastroliths 7. Carbonization

2. Dissolution 8. Gnawings

3. Coprolites 9. Mummification

4. Lithification 10. Cast

5. Encrustations 11. Refrigeration

6. Mold 12. Tar Impregnation