>>Each age had a dominant to predominant type of deposition. There is the
>>widespread quartzites of the lowest Cambrian, the mottled, algal dolomites
>>of the lower Ordovician (Beekmantown, Red River etc), the red-beds and salt
>>of the Silurian, the black shales of the Devonian, the Crinoidal limestones
>>of the Mississipian, the coals and cyclicity of the Pennsylvanian, the
>>redbeds and salt of the Permian and Triassic, the oolites of the Jurassic,
>>the chalk and greensands of the Cretaceous, and the diatomites of the lower
>>Tertiary. Today we have widespread clastic deposition. This is merely a
>>continuation of what we have seen in previous geologic periods, only a
>>different lithology
Art Chadwick replied:
>You raise an interesting question... Why is the geologic record a
singularity?
>Why are different periods successively different lithologies (and different
>paleocurrent patterns?)
Plate tectonics. The Earth WAS different at different times in the
geologic past. You're hinting, perhaps, that a global flood could be
responsible for such differences but I've yet to see a coherent explanation
of how a global flood could produce the stratigraphic column as we see it.
- Steve.
-- Steven H. Schimmrich KB9LCG schimmrich@earthlink.edu Department of Physical Sciences Kutztown University 217 Grim Science Building, Kutztown, PA 19530 (610) 683-4437 http://www.uiuc.edu/ph/www/s-schim Fides quaerens intellectum