CHAPTER 2: Floods, Fossils and Heresies

 

Biblical View

1) The earth is 6,000 years old.

2) All life was created at the same time.

3) The presence of marine fossils in the rock record is proof of the great Biblical Flood.

4) The Biblical Flood created vast accumulations of debris seen today as mountains.

5) The earth subsequently began to decay through erosional processes and continues to decay today.

 

Fossils

1) Fossils are recognizable evidence in the rock record of pre-existing life forms.

2) Animal fossils may consist of preserved hard parts such as shells and bones. Plant fossils may be preserved as petrified wood.

3) In rare circumstances, the soft parts of organisms can also be preserved (i.e. Middle Cambrian Burgess Shale in British Columbia).

4) The activity of ancient organisms such as tracks, trails and burrows can also be preserved in the rock record. Plants can leave imprints of leaves, bark, branches etc.

 

Leonardo Da Vinci

1 ) Italian philosopher

2) Around 1500, examined rock strata of northern Italy.

3) concluded that fossils in limestone represented early life forms.

4) many similar to marine organisms living today.

5) reasoned that fossils deposited in place

6) fossil rich rock layers separated by layers devoid of fossils

7) suggested fossil-rich layers deposited by several flood events rather single, worldwide deluge.

 

Robert Hooke

1) Famous British scientist.

2) studied and sketched fossil shells during late 1600's and early 1700's.

3) argued against conventional wisdom that fossils deposited during Biblical Flood.

4) fossiliferous rocks recorded multiple floods.

5) recognized extinctions in the rock record.

6) fossils had fixed life spans.

7) fossils could be used to compare rock units of similar age.

 

Nicholas Steno

1) Italian scientist

2) Recognized that many rock units deposited in horizontal layers (stratification)

3) In 1669, stated three basic principles for chronological analysis of rock record

(a) Principle of Superposition: In a succession of undeformed strata, the oldest stratum lies on the bottom with successively younger ones above.

(b) Principle of Original Horozontality: Most strata initially deposited horizontally. Strata that are inclined or folded must have suffered disturbance subsequent to deposition.

(c) Principle of Orgininal Lateral Continuity: Strata originally extended in all directions until they thinned to zero or terminated against the edges of the basin of deposition.

 

 

Fossils and Geologic Mapping

1) Rock units not continuously exposed.

2) Surface exposures usually separated by great distances.

3) Correlation involves matching rock unit in one exposure with counterpart at different locality.

4) In 1723, English naturalist John Woodward suggested using fossils to correlate strata in England with European counterparts.

5) Also use color, minerals, etc.

6) Construct geologic maps.

 

William Smith

1) In late 1700's, recognized widespread regularity of strata in England

2)prepared first high quality geologic map.

3) able to trace and map different strata throughout large areas of England.

4) used criteria such as color, mineral composition and distinctive fossils to correlate.

 

Georges Cuvier and Alexandre Brongniart

1) prepared geologic map of northern France during time when William Smith surveyed England.

2) mapped distribution of various rock divisions based upon similarity of fossils.

3) Simultaneous but independent discovery in England and France that strata could be distinguished by fossils was a major scientific breakthrough in constructing geologic maps.

 

Fossils

1) Fossils are the recognizable evidence in the rock record of pre-existing life forms.

2) Animal fossils may consist of preserved hard parts such as shells and bones. Plant fossils may be preserved as petrified wood.

3) In rare circumstances, the soft parts of organisms can also be preserved (i.e. Middle Cambrian Burgess Shale in British Columbia).

4) The activity of ancient organisms such as tracks, trails and burrows can also be preserved in the rock record. Plants can leave imprints of leaves, bark, branches etc.

 

Criteria Defining a good Index Fossil

(a) Easily recognized

(b) Widespread in occurrence

(c) Restricted to a very limited thickness of strata

 

 

CATASTROPHISM

Cuvier:

1) determined that fossil species in one group of strata differed from those in other strata above and below.

2) attributed these differences to extinction of species.

3) sedimentation discontinuous and interrupted by periods of erosion and abrupt changes in fossil assemblages.

4) argued that the rock record recorded many catastrophic extinctions.

5) noted that fossils in successively younger strata appeared more like modern organisms.

6) used the term catastrophism in referring to the abrupt extinction of certain organisms followed by the appearance of different species in overlying younger strata.

7) implied that all organisms were created early in earth's history and afterwards subjected to selective extinctions.

 

CATASTROPHISM AND SPECIAL CREATIONS

Alcide D'Orbigny (1859):

1) postulated that new species were created following extinction of older life forms.

2) referred to as catastrophism and special creations.

3) This theory placed little or no connection between index fossils of successive groups of strata.

 

DECENT BY EVOLUTION

1) theory suggested as early as the 1700's

2) alternative to catastrophism

3) proposed a connection between the different fossils in successive strata

4) younger organisms were the descendants of older ones

5) species that survived various catastrophic events somehow changed through time.

6) theory generally not accepted until the 1800's and Charles Darwin.

 

THE COSMOGONISTS

1) The early earth was hot and glowed like the sun.

2) As the earth cooled, a primitive hard crust formed.

3) During formation of the early earth, water and atmosphere segregated according to relative densities.

4) the interior of the earth had a fiery core surrounded concentrically by solid material.

 

 

Giovanni Arduino (1759)

distinguished rocks in northern Italy into several groups:

(a) Primitive Mountains composed of non-fossiliferous metamorphic and intrusive rocks.

(b) Secondary Mountains consisting of fossiliferous limestones and shales.

(c) Tertiary Mountains of the foothills composed of clay, sand and limestone.

(d) Youngest volcanic rocks.

 

NEPTUNISM

1) General theory that the entire earth's crust is related to the sea.

2) In Germany, early geologists studied large horizontal beds of sedimentary rocks known to be deposited by the sea.

3) Basaltic rocks sandwiched between sedimentary layers also considered deposited by sea.

4) Abraham Werner (1787) provided detailed account of the chronological succession of strata:

(a) Schists and granites earliest precipitates

(b) Transition sandstones and limestones deposited as sea retreated

(c) Flat-lying secondary sedimentary rocks

(d) Alluvial deposits precipitated in lowlands

 

 J. Lehmann (mid 1700’s):

1) argued that all rocks were deposited in the sea.

2) interpreted three major rock divisions:

(a) highly-deformed strata devoid of fossils and intruded by dikes during Creation.

(b) relatively undeformed, fossiliferous strata deposited during Biblical Flood.

(c)post-Deluge units deposited by earthquakes, volcanoes and landslides.

 

 

PLUTONISM

Geologists working in England and Scotland correctly interpreted the basaltic rocks to be volcanic.

1) observed that ancient strata within the interior of continents were deformed whereas recent strata were deposited along coastlines.

2) reasoned that construction of new products on the earth's surface was balanced by destruction of the old.

3) envisioned the earth as a great heat engine where mountains were raised, eroded away and raised again.

 

James Hutton

1) attacked concept of catastrophism.

2) argued that formation of mountains and valleys occurred over time period > 6000 years.

3) schists, basalts and granites not deposited by the sea.

4) basalts formed by hot, molten material.

5) great pressures and intense heat deep within the earth caused volcanic eruptions.

6) heat was responsible for the upheaval of rocks to form mountains.

7) granites, veins, and basalts formed during such events.

8) Mountains formed by repeated dynamic convulsions of the crust.

 

UNIFORMITARIANISM

1) Hutton thought processes acting today same as throughout earth history.

2) British geologist Charles Lyell published several versions of his famous book Principles of Geology between 1830-1875.

(a) Lyell adopted more extreme views of uniformity than had Hutton.

(b) Lyell's theory known as uniformitarianism.

(c) believed that geologic processes acting today also acted throughout earth history.

(d) argued that the rates and intensities at which these processes acted were uniform throughout time.

(e) Example: frequencies of earthquakes and volcanic eruptions observed today were the same throughout geologic history.

 

GRADUALISM

1) Lyell's brand of uniformitarianism

2) belief of a delicately balanced, or steady state, view of the earth

3) steady flow of material and energy into and out of a system

4) system overall remains unchanged.

 

ACTUALISM: The modern doctrine of Uniformitarianism

1) Earth history records both catastrophic and uniform, steady-state events but is generally evolutionary and builds upon these historic events.

2) Earth history can be regarded as the competition and interaction among different processes which overall tend towards equilibrium (steady state) but never achieves it.

3) There are some natural processes active in the past that may no longer be important on earth (early differentiation of the earth, formation of the early atmosphere, precipitation of banded iron formations, etc.).

4) The principles of nature have been uniform through time. Although rivers, ocean basins, continents and life have changed through time, the laws which describe those changes have remained the same.

5) Rates and intensities of geologic processes have varied throughout geologic time.