The Golden Rule of Geology
Every Major Geologic Formation on earth was deposited with-in a few hundred miles of sea level
Changes in lithology DO NOT usually represent changes in regional environment!
Major Changes in environment are represented by major shifts in depositional environments and accompanying mountain building events
- Many geologist do not utilize facies relationships in paleo-geographical interpretations. They explain every change in lithology (I.e. a shift from sandstone to shale or gravel layers) as a major shift in regional paleo-environment. They say “A desert covered this area and deposited the sandstone, then things totally changed and millions of years later lakes covered the area. Then things totally changed again and the ocean covered the area millions of years after that…
- The truth is that most adjacent layers were simultaneously in the same depositional system. (I.e. gravels …lakes.. Ocean… explain better… This interpretational method is called Sequence Stratigraphy. Major changes in environment only occur every 3-6 layers and are evidenced by orogenic events and relatively rapid sea displacement.