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Chap.1-7 Notes.Hist. Geology


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deals with the evolution of the Earth and its’ life forms.
Historical Geology
deals with classification of Earth materials and the processes that form the Earth’s landscapes and ocean floors.
Physical Geology
- Observation
- Formulation of hypothesis
- Testing
- Construction of Theories
- Scientific Laws (after validation of theories~200 years)
Scientific Method
early dating without the use of absolute numbers
Relative (Qualitative dating)
(Nicolaus Steno) Oldest bed on bottom and youngest bed on top.
Principle of superpositon
(James Hutton, Father of Geology):
- The Earth has evolved in a constant and uniform manner
- “Present is the key to the Past” Formation of geologic features found on the Earth in the past can be explained by natural processes that occur
Principle of Uniformitarianism
Each period of time has an unique and characteristic set of fossils.
- Fossils succeed one another in a definite and recognizable order.
- The younger the rock the more complex the fossil
Principle of Biological Succession
(Sir Charles Lyell) This principle states that geologic features such as faults, veins, and dikes must be younger than the rocks or features across which they cut.
Principle of Cross Cutting Replationship
(Lyell)Principle of ______(rock fragments) are always older than the host rock. Fragments within larger rock masses are older than the rock masses in which they are enclosed. Whenever two rock masses are in contact, the one containing pieces of the other
Principle of inclusion
Sediments are deposited in flat, horizontal layers.
(Steeply dipping or folded rock layers indicate tectonic disturbance after deposition.)
Principle of Original Horizontality
Sediments are deposited over a large area in a continuous sheet. Rock layers extend continuously in all directions, until they thin out at the edge of the depositional basin, or grade into a different type of sediment.
Principle of Original Lateral Continuity
Study of layered rocks, including their texture, composition, arrangement, and correlation from place to place.
Discipline of Stratigraphy
Determining the equivalence of two rocks in two different localities
Use of Correlation
Time of no life
Age of ancient life
Paleozoic Era
Middle life such as the age of the dinosaurs
Mesozoic Era
Recent life (such as mammals and flowering plants). Age of the mammels
Cenozoic Era
Nearly flat‑lying strata overlying eroded edges of inclined or tilted older strata. Produces a gap in time known as a hiatus
Angular Unconformity
igneous or metamorphic rocks overlain by horizontal sedimentary rock. The intrusive igneous or metamorphic rocks are older than the overlying sedimentary rocks.
Example: Grand Canyon
beds above and below the unconformity are parallel and horizontal to one another. The beds are separated by an erosional surface creating a hiatus
Atoms that spontaneously decay
The time in which one-half of an original amount of a radioactive atoms decays to daughter products.
Half life
The radioactive isotope which undergoes decay is
Parent element
The parent element undergoes radioactive decay to form a
Daughter element
- EX: U238 to Pb206 (uranium to lead).
- Atomic number decreases due to decay of the nucleus
Decay from Parent Product to Daughter Product
Is 4.6 Billion Years Old (Lunar & Meteorite Samples)
Age of Earth
Life as we may know it, began 600 million years ago (4 billion years to set the “Stage for Life”
Life began...
Accounts for 87% of Geological Time
Precambrian time
record the rise and fall of the ocean. Form by lithification of sediments. (Rock fragments, Chemical Precipitates, Organic material) Can be deeply buried and subjected to heat and pressure that converts them to metamorphic rocks.
Sedimentary rocks
Record thermal events. Form by solidification. Can be weathered and eroded to form sediment (gravel, sand, silt, clay).
Igneous rocks
Record folding and mountain building events. Form by heat, pressure, and chemical activity. May be heated to temperatures so great that they melt.
Metamorphic rocks
The process by which loose sediment is converted to coherent solid rock by any of several processes: precipitation of a cementing material around individual grains, compaction, or crystallization.
Includes: Weathering
Conglomerate or Breccia
Shale or Claystone
Clastic Texture of Sedimentary rocks
Non Clastic Texture Sedimentary Rocks Composed of Chem Precips & Organics
Include Shields & Platforms. The long-stable region of a continent, commonly with Precambrian rock, either at the surface or only thinly covered with younger sedimentary rocks.
Large areas of exposed ancient crystalline rocks. (Canadian shield) A component of cratons.
Basement rock covered with sed. Rock (US Midwest). That part of a craton covered thinly by layered sedimentary rocks and characterized by relatively stable tectonic conditions.
Linear mountain systems formed through compression. Great linear tracts of deformed rocks, primarily developed near continental margins by compressional forces accompanying mountain building.
Orogenic Belts
Marine environment
Nearly flat, smooth surfaces extending from the shoreline to 600 feet in water depth. The flooded edge of the continent. Flooding occurred when the glaciers melted at the end of the last Ice Age, about 10,000 years ago.
Relatively flat (slope <
Continental shelves
Steep slopes that extend from the seaward edge of the continental shelves down to a water depth of 6000 feet. The steeper slope at edge of the continent.
Located seaward of the continental shelf.
Boundary between continental and oceanic crust
Continetal slopes
Deposited by turbity currents that flow down submarine canyons
Deep sea fans
Large fluvial depocenters at the lands edge.
Fan-shaped accumulations of sediment
Formed where a river flows into a standing body of water, such as a lake or the sea
Coarser sediment (sand) tends to be deposited near the mouth of the ri
Are those environments at or near the transition between the land and the sea
Transitional environments
Delta front composed of sands and clays (very diversified marine fauna)
Foreset beds
Continental deposition
Nonmarine environments
river environments consisting of point bar deposition and cutbank erosion
What color are we taling about? Black or dark-gray coloration indicate high levels of organic material –Ex: Shale
Color: Black
(Color of sedimentary rocks provides useful clues to the depositional environment)
Brown, red green indicate the presence of iron oxide minerals and oxidation (exposure of the rock to oxygen in the atmosphere) –Ex: Red Beds (Clays and Sandstones)
Color: Red (Color of sedimentary rocks provides useful clues to the depositional environment)
Well sorted sand within a narrow size range indicates a mature sandstone (a long process of transportation and deposition as in beach deposits, eolian dune deposits, and some fluvial deposition)
Maturity includes; Size and sorting
Rounding and Sphericity: Angular grains as in conglomerates indicate immature sedimentation close to the source area
Maturity includes; Grain shape
Size, Sorting, Grain Shape and Color. Can be deposited in marine and nonmarine environments.
Limestones are predominantly deposited in a marine environment
Black coloration due to organic content. Can be deposited in marine and nonmarine environments
Determining the equivalence of two rock bodies in two different localities. May use lithologic position, lithology, or fossils in correlation. Used in the construction of Geologic Columns and Cross-Sections
Primarily indicates a generalized Environment of Deposition.
Include Eons, Eras, Periods and Epochs
Time Units
Map showing the geography of an area at a specific time in geological past. Shows the distribution of land and water during specific periods of time.
Paleogeographic map
What type of map shows thickness? Shows the changes in thickness of the formation or stratigraphic unit. The zero isopach represents the boundary of the rock unit.
–True Basin Edge (Presence of Sand!)A map depicting the thickne
Isopach map
Rock that strongly indicates the Environment of Deposition (Marine or Nonmarine). A particular aspect of sedimentary rocks that is a direct consequence of sedimentation in a particular depositional environment. It allows identification of the environment
Interpretations, i.e. land and ocean. When the differentiating characteristics are lithologic (rather than biologic), facies can be designated as lithofacies
Lithofacies maps
Molecular exchange of the original organic material with inorganic minerals (SiO2) –Ex: Petrified Wood A fossilization process in which the original skeletal substance is replaced after burial by inorganically precipitated mineral matter
Soft tissues are persevered as thin films of carbon
–Ex: preservation in shale. The concentration of carbon during fossilization
Impression of organisms left in the rock
Molds and casts
Tracks, trails, burrows, and other markings made in now lithified sediments by ancient animals.
Shows the animals behavior –Examples: Biped or Quadruped?
–Feeding behavior
Trace fossil
- Classification of life based on Morphology (anatomy of the organism).
- Utilizes the Linnaean System of binomial nomenclature (genus and species) Organisms are grouped based on their similarities into taxonomic groups or taxa.
Kingdom: Anim
–Contains RNA
–DNA Absent
–Needs host cell to reproduce
HIV Virus
–Self Replicating
–Transcribes to RNA
–RNA translates to ribosomes or mitochondria
–Protein synthesis
Responsible for life
Demonstrated that physical characteristics can jump generation
⬢Ex. Planted seeds from small pea plants which generated some tall pea plants.
⬢Ex. Two brown eyed people have a blue eyed baby.
⬢Ex. A son goes bald but the father an
Mendelain Principles of Inheritance
- Transfers genetic information
–Composed of nucleotides
–Series of nucleotides compose a gene (factor for specific inherited traits)
– Series of genes compose a chromosome
– Chromosomes are paired
– Humans have 23
DNA: Deoxyribonucleic Acid
A stable and inheritable change in a gene.Spontaneous change in the chemical organization of the DNA molecule that is replicated and passed on to succeeding generations as a new gene expression (can be good or bad)
a group of interbreeding individuals of the same species composing a specific gene pool. A group of individuals that live close enough together so that each individual has an equal chance to mate with all members of the opposite sex within the group.
Population of similar individuals that can interbreed and produce fertile offspring
The evolution of a new species via adaptive radiation (certain individuals become highly adapted to a particular environment and living strategy)
Species may exist for several millions of years with little or no change and speciate rapidly in a short period of time.
Punctualistic model or puctualistic evolution
Species are continuously adapting, mutating, and speciating through time.
Gradualistic model
–Vestigial Organs
•Coccyx, Appendix, Whale Pelvis
Soemthing we don't need
- Horse fossils
Paleontological Clue
Interval of time that a species exists
Geological range
Fossils that are restricted to a narrow range
–Short lived
–Highly adapted to environment
–Quickly become extinct.
Fossil with a wide geographical distribution but narrow stratigraphic range and thus useful in correlating st
Index fossils
Combination of several species within a stratigraphic unit (formation) –Significantly narrows the age of the rock.
Assemblage zones
The study of the relationship of ancient organisms to their environment.
Rifting of the Mesozoic Supercontinent of Pangaea
Is descriptive and does not offer a mechanical explanation for the drift
Continental Drift
Freshwater reptile found along coastlines of Brazil and West Africa
Ridges: Splits in the seafloor –
Trenches: Linear depressions along coastlines
Bathymetry of Seafloor
Seismic and volcanic activity is associated with ridges and trenches which define the Plate Boundaries
Cross-Section of Seafloor and Continental Mountain Belt
⬢Shows Divergent Ridge Boundary and Convergent Trench Boundary (Subduction)
Mechanism of Plate movemnt
Global Movement of the Lithospheric Plates
Plate tectonics
Exposure of the rock to oxygen in the atmosphere
Represents the boundary of the rock unit
- Eroisonal
- True basin edge
- (Presence of sand)
Zero Isopach
Only 10% of the bio mass is transferred across each _______. The rest is needed to live.
Trophic Level
Practice Photosynthesis (Plants & Phytoplankton)
(100 biomass units)
Which trophic level? Omnivores; Respiration
Which trophic level? Carnivores - meat eaters
One Unit
10 Units; Herbivores;
Consumers; Animals & Zooplankton
How many chromosomes do we have
Females are..
Males are...
Humans have _____ pairs of chromosomes (half from mom and half drom Dad)
What is life
Self replicating
- Embryology
- Conservative properties of DNA
Biological Clues
Name the supercontinent of the Mesozoic?
____ are a major division of geologic time. _____ are divided into geologic periods. There are three ____ in the Phanerozoic Eon. In order from oldest to youngest, they are as follows:

Paleozoic Era - "ancient life" (such as trilobi
Eras are divided into periods.
Taxonomy from largest to smallest
Kingdom, Phylum, Class, Order, Family, Genus, species
Anatomy of the organism

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