Information About

Lithostratigraphy




Lithostratigraphy is the Geological Science associated with the study of Stratum or rock layers. Major focuses of the study include Geochronology , Comparative Geology , and Petrology . In general a stratum will be primarily Igneous or Sedimentary relating to how the rock was formed.


SEDIMENTARY LAYERS


Sedimentary layers are laid down by Deposition of Sediment associated with Weathering processes. These layers are distinguishable as having many Fossils and are important for the study of Biostratigraphy .


IGNEOUS LAYERS


Igneous layers are either Plutonic or Volcanic in character depending upon the Cooling Rate of the rock. These layers are generally devoid of fossils and represent intrusions and volcanic activity that occurred over the geologic history of the area.


APPLICABLE PRINCIPLES


There are a number of principles that are used to explain the appearance of stratum:

  • The principle of intrusive relationship states that when an igneous rock cuts across a formation of sedimentary rock, then we can say that the igneous intrusion is younger than the sedimentary rock.

  • The Principle Of Superposition states that a sedimentary rock layer in a tectonically undisturbed stratum is younger than the one beneath and older than the one above it.

  • The principle of original horizontality states that the deposition of sediments occurs as essentially horizontal beds.