Saturday, 26 November 2011

Lithostraticgraphic correlation

This is based on recognising rock types, or more usually, a sequence or succession of rocks.

Methods of lithostratigraphic correlation

  1. You could correlate using a sequence of beds
  2. Looking at the thickness of beds -thickness of thin and thick bars. such a correlation might work for identifying where you are in a coal field
  3. Composition of beds may be distinctive if a rare mineral present in a bed. The Cretaceous- Tertiary boundary rocks are correlated on the presence of iridium     

Problems of lithostratigraphic correlation
  1. lateral variation - where sediment change type horizontally - deltas- sediments at source may be thicker, further away thinner 
  2. Diachronous beds - where sediment type is laid down at different times e.g delta over the years, a continuous layer of sands is left behind. these sands get younger from land to sea -  they are definitely not the same age.

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