Download Principle of Superposition and Unconformities

Mountains BrainPOP has
good examples of
unconformities
The Tales Rocks Tell and the Changes to the Story
 Danish Catholic Bishop and Scientist
 Started in anatomy but fossils
expanded his work into geology
 Introduced the concept of the
Principle of Superposition,
Unconformities and fossils being
part of once living organisms.
 Scottish Farmer
 Started in medicine but chemistry
expanded his work into geology
 Introduced the concept of the Rock
Cycle (before Hutton it was thought
that rocks precipitated out of water)
 Introduced the concept of Deep
Time (Earth is millions of years old)
 Before Hutton the Earth was
thought to be about six thousand
years old (Oct. 22, 4004 BC)
 In rock layers (strata) the oldest rocks are
on the bottom and the newest rock is on
the top.
 This allows you to find the relative age
(older/newer) of the rocks based on their
position.
 Analogies:
 The dirty clothes pile
 Magazines
 Unconformities are changes that occur
in the rock layers (strata).
 Unconformities can be caused by plate
tectonics (earthquakes), volcanic
activity (magma pushing and lava
flows), erosion (water and glaciers),
lack of deposition (no new sediment is
deposited over a long period), etc.
A
B
This is NOT a
man made layer.
C
D
E
F