FLOODS, FOSSILS AND HERESIES

FLOODS, FOSSILS AND
HERESIES

“NO VESTIGE OF A BEGINNING,
NO PROSPECT OF AN END”JAMES HUTTON


James Hutton
Father of Geology


Pre Age of Enlightment
❧Bishop Ussher 1654
❧Biblical Chronology
Based on generations
❧Earth created on October 23, 4004
B.C. at 9AM
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FOSSILS
❧ Recognizable evidence of pre-existing life
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Perfect preservation of organisms

Impressions- casts and molds
Shells- original or replaced
Bones- original or replaced
Plant structures- trunks, leaves
Trace fossils- tracks, burrows, borings
Fecal matter (coprolites)


Da Vinci’s Insight
❧ In 1500 C.E. Leonardo Da Vinci recognized that
fossil shells in the layered rocks represented ancient
marine life
❧ Observed that many fossil rich layers were separated
by unfossiliferous layers thereby repudiating the
concept of one flood
❧ Had the idea that seasonal events responsible



Nicolas Steno
❧ Danish Naturalist and Physician working for the
Duke of Tuscany
❧ Widely circulated writings
❧ Fossils formed together with the rocks in which
they occur
❧ 1669 stated the 3 most basic principles
❧ Stratification- horizontal layering
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Inferred that differences in strata reflected

differences in conditions (temperature, wind,
currents, storms)


Principles Used to Determine
Relative Age- Nicolas Steno
❧Original Horizontality●

Because particles settle from fluids under gravity,
stratification MUST be horizontal

❧Superposition
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Progressively younger from bottom => top

❧Lateral Continuity
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Strata originally extended in all directions until it
thinned to zero or terminated at margin (basin of
deposition)





Unconformities
❧ Unconformity - surface that represents a gap in the
geologic record

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Disconformity - contact representing missing
parallel beds of sedimentary beds
Angular unconformity - younger strata overlie
an erosion surface on tilted or folded layers
Nonconformity - erosion surface on igneous or
metamorphic rock


Utility of Fossils
❧ John Woodward

1723, Correlation of strata in England and
European mainland based on “great numbers of
shells”
❧ Geologic Mapping
● 1746, crude geologic map showed continuity of
chalk beneath the English Channel
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William Smith, canal engineer
❧ The Map that Changed the World,

❧ 1796 wrote “wonderful order and regularity with
which nature has disposed of these singular
productions [fossils] and assigned to each its class
and peculiar stratum”
❧ 1815 Publication of the 1st geologic map of England
intended for the development of canals, quarries and
mines as well as natural resources




William Smith’s "Strata Identified by
Organized Fossils"
❧ Soon after the first issue of his great geological map of England in 1815,
William Smith published the Strata Identified by Organized Fossils.
❧ It was intended as a kind of geological users manual with illustrations to
identify fossils.
❧ But Smith’s work went beyond the mere illustration of fossils. Smith had
deciphered the hieroglyphics of nature-the distinctive inscriptions borne
by the different strata. With the Strata Identified . . . and its colored plates
in hand, anyone would be able to compare the plates with fossils collected
in the field and immediately identify the strata from which they came.
❧ The strata once identified, their place in the orderly succession of the
strata-which lay above and which lay below, as Smith had determined it was then known. All this, Smith wrote, "without the necessity of deep
reading, or the previous acquirement of difficult arts."



Georges Cuvier and Alexandre
Brongniart- Paris Basin

❧ Development of geologic map of Paris Basin
❧ The strata of the Paris Basin were close to horizontal.
As of
❧ 1811, Cuvier and Brongniart employed fossils but
only in the few instances where more obvious
evidences of sequence were absent.
❧ The title of their work was Géographie
Minéralogique by which they meant the distribution
of what Werner had called the "external"
characteristics of the mineral and fossil contents,
shapes, colors, and textures of the strata within the
Paris basin.
❧ Today call this lithology. They determined the order
of the strata from their superposition, their lithology
and by tracing them across the basin
❧ Cuvier firmly established the fact of the extinction of
past lifeforms



Correlation
❧ Physical Continuity of Lithologic Units
❧ Similarity of Rock Types
❧ Superposition
❧ Correlation by Fossils
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Principle of Faunal Succession
Index Fossil
Fossil Assemblage



Correlation
❧ Correlation by Fossils
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Principle of Faunal Succession
• Wm. Smith & Georges Cuvier
• Organism succeed one another in lithologic strata
• One organism will NOT be found in rocks of widely different ages

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Index Fossil
Easily recognizable/Easily identifiable
• Wide geographic distribution
• Of limited life span as a species
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Fossil Assemblage