Topic 9:  READING HISTORY IN THE ROCKS

Philosophy:

1.)  Gives a unified view of the universe.
2.)  Makes a person a more critical thinker.


Tools of Philosophy

1.)  Reason - to begin with axioms or general principals and use them 
to arrive at certain conclusions (the deductive method).  Rene Decartes 
(1596-1650) believed that the deductive method was the only way to 
arrive at truth.  The usefulness of deductive reasoning depends on how 
true the original axioms are.  Geometry is a good example of the use of 
deductive reasoning.

2.)  Observation - to begin with particular facts and then draw broad 
conclusions (inductive method).  This is known as empiricism. For example, 
I observe that a very hard rain falls at the rate of 1 inch per hour.  
Supposedly, Noah's flood lasted 40 days.  Hence I can use the inductive 
method to test the validity of Noah's flood.  Continuing at the same rate 
of 1 inch per hour, two feet a day can fall each 24 hour period.  At the 
end of 40 days, the surface of the earth would be covered with 80 feet 
of water.  Obviously, this is not enough rain to completely flood the earth.

3.)  Faith - knowing by faith.  Faith is the way we come to know things.  
If a person has faith that God exists, he firmly believes that God exists, 
despite any arguments against this belief.

4.)  Intuition - mysterious revolution.  Philosophers believe that there 
are some things we can experience of know directly without reasoning 
about them or testing them.


Aristotle (384-322 B.C.) made valuable contributions to both deductive 
and inductive logic.  Aristotle sought to find cause-and-effect relationships 
between things in the world.  However, he believed in a first "uncaused 
cause" or God, and considered theology the highest science.

St. Thomas Aquinas (1225-1274) argued that the universe was organized 
on the basis of reason, and that knowledge if it leads to God.  He said that 
a person should use both faith and reason in believing in God.  He believed 
that the happiness of understanding is the greatest happiness of all.

Roger Bacon (1214-1294) argued strongly for the scientific methods, as 
opposed to reliance on authority, for understanding natural phenomena.

Leonardo da Vinci (1452-1519) --  Here a doubt arises and that is whether 
the deluge, which happened at the time of Noah, was universal or not.  And 
it would seem not, for reasons now to be given".  He argues that, it were a 
flood ten cubits deep over the whole sphere of the earth, the waster would 
have nowhere to go after it stopped raining;  the food would never subside.  
However, there were still some major questions to be answered. da Vinci 
continued: "why do we find the bones of great fishes and oysters and corals 
and various other shells and sea-snails on the high summits of mountains by 
the sea, just as we find them in low seas?" (Croben, 1991).

Fernard Pallissy (1510-1589) examined fossils with the care of a craftsman 
and saw how similar they were to living organisms.  He argued against the 
belief of Martin Luther that fossils were left over from the Flood, but that 
idea took over the thinking of many Christians for several centuries.  
(Croben, 1991).

James Ussher (1581-1656), archbishop of Armagh in Northern Ireland, set 
the date of creation as 4004 BC.


Stratigraphy

Stratigraphy - the study of strata (i.e., rock layers).  The key governing 
principle is called uniformitarianism.

Uniformitarianism - This is the geological principle which says that 
the geological processes operating at present are the same processes 
that have operated in the past. "The present is the key to the past".

Formations - are bodies or rock of considerable thickness with 
recognizable characteristics.

Contacts - are surfaces separating two different rock types or rocks of 
different ages.  If deposition is not continuous then we say that there is 
a break in the stratigraphic record.  Several types of breaks in the 
geological record are listed as follows:

Unconformities - Contacts representing buried erosion surfaces.  An 
unconformity is a substantial break or gap in the stratigraphic sequence. 
 There are three types of unconformities.

Angular unconformity - is marked by an angular discontinuity between 
older and younger strata.

Disconformity - is an irregular surface of erosion between parallel strata.

Nonconformity - is where strata overlie igneous or metamorphic rocks.

Relative Time -  To determine the relationship of geologic events to one 
another, three basic principles are applied on at a time.

Original horizontality - This principle states that beds of sediment deposited 
in water  formed as horizontal or nearly horizontal layers.  The few exceptions 
such as cross-bedding associated with fluvial deposits are easily indentifiable.

Superposition -  This principle states that within a sequence of 
undisturbed sedimentary rocks, the layers get younger in going 
from bottom to top.  If sedimentary rock is formed by sediment 
settling onto the sea floor, then the first (or bottom) layer must
be there before the next layer can be 
deposited on top of it.

Cross-cutting relationships -  This principal states that a disrupted
pattern is older than the cause of the disruption.  A layer cake 
(the pattern) has to be baked (established) before it can be sliced 
(the disruption). 

Correlation - this means determining the age relationships between 
rock units or geologic events in separate areas.  There are various
 methods of correlations.

Physical continuity -  being able to trace physically the course of 
a rock unit is one way to correlated rocks between two different places.  

Similarity or rock types - correlation between two regions can be 
made by assuming that similar rock types in two regions formed 
at the same time.  

Correlation by fossils - Plants and animals that lived at the time
 the rock formed were buried by sediment, and their fossil remains 
are preserved in sedimentary rock.  Because plants and animals 
evolve and change with time, any group of fossils represents one 
unique period of time.  Rocks from different places which contain 
the same fossil assemblage correlate.

Faunal succession -  This principle states that fossil species 
succeed one another in a definite and recognizable order.

Index fossil - a fossil from a very short-lived species known 
to exist during a specific period of geologic time.

Fossil assemblage -  several different fossils which existed at 
one time.

The Standard Geologic Time Scale - based on fossil assemblages, 
the geologic time scale subdivides geologic time.  The geologic 
time scale, representing an extensive fossil record, consists of 
three eras, which are subdivided into periods, which are in turn,
 divided into epochs.

ERA	PERIOD	EPOCH	AGE (Ma)

Cenozoic	Quaternary	Holocene (recent)	0 - 0.1
		Pleistocene	0.1 - 1.6
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	Tertiary	Pliocene	1.6 - 5.3
		Miocene	5.3 - 23.7
		Oligocene	23.7 - 36.6
		Eocene	36.6 - 57.3
		Paleocene	57.3 - 66
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Mesozoic	Cretaceous		66 - 144
	Jurassic		144 - 208
	Triassic		208 - 245
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Paleozoic	Permian		245 - 266
	Pennsylvanian		266 - 320
	Mississippian		320 - 360
	Devonian		360 - 408
	Silurian		408 - 438
	Ordovician	 	438 - 505
	Cambrian		505 - 570	
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Precambrian Time